what are fallacies in critical thinking

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Critical Thinking and Decision-Making  - Logical Fallacies

Critical thinking and decision-making  -, logical fallacies, critical thinking and decision-making logical fallacies.

Critical Thinking and Decision-Making: Logical Fallacies

Lesson 7: logical fallacies.

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Logical fallacies

If you think about it, vegetables are bad for you. I mean, after all, the dinosaurs ate plants, and look at what happened to them...

Let's pause for a moment: That argument was pretty ridiculous. And that's because it contained a logical fallacy .

A logical fallacy is any kind of error in reasoning that renders an argument invalid . They can involve distorting or manipulating facts, drawing false conclusions, or distracting you from the issue at hand. In theory, it seems like they'd be pretty easy to spot, but this isn't always the case.

Watch the video below to learn more about logical fallacies.

Sometimes logical fallacies are intentionally used to try and win a debate. In these cases, they're often presented by the speaker with a certain level of confidence . And in doing so, they're more persuasive : If they sound like they know what they're talking about, we're more likely to believe them, even if their stance doesn't make complete logical sense.

False cause

One common logical fallacy is the false cause . This is when someone incorrectly identifies the cause of something. In my argument above, I stated that dinosaurs became extinct because they ate vegetables. While these two things did happen, a diet of vegetables was not the cause of their extinction.

Maybe you've heard false cause more commonly represented by the phrase "correlation does not equal causation ", meaning that just because two things occurred around the same time, it doesn't necessarily mean that one caused the other.

A straw man is when someone takes an argument and misrepresents it so that it's easier to attack . For example, let's say Callie is advocating that sporks should be the new standard for silverware because they're more efficient. Madeline responds that she's shocked Callie would want to outlaw spoons and forks, and put millions out of work at the fork and spoon factories.

A straw man is frequently used in politics in an effort to discredit another politician's views on a particular issue.

Begging the question

Begging the question is a type of circular argument where someone includes the conclusion as a part of their reasoning. For example, George says, “Ghosts exist because I saw a ghost in my closet!"

George concluded that “ghosts exist”. His premise also assumed that ghosts exist. Rather than assuming that ghosts exist from the outset, George should have used evidence and reasoning to try and prove that they exist.

Since George assumed that ghosts exist, he was less likely to see other explanations for what he saw. Maybe the ghost was nothing more than a mop!

False dilemma

The false dilemma (or false dichotomy) is a logical fallacy where a situation is presented as being an either/or option when, in reality, there are more possible options available than just the chosen two. Here's an example: Rebecca rings the doorbell but Ethan doesn't answer. She then thinks, "Oh, Ethan must not be home."

Rebecca posits that either Ethan answers the door or he isn't home. In reality, he could be sleeping, doing some work in the backyard, or taking a shower.

Most logical fallacies can be spotted by thinking critically . Make sure to ask questions: Is logic at work here or is it simply rhetoric? Does their "proof" actually lead to the conclusion they're proposing? By applying critical thinking, you'll be able to detect logical fallacies in the world around you and prevent yourself from using them as well.

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Common Critical Thinking Fallacies

Critical thinking is the process of reaching a decision or judgment by analyzing, evaluating, and reasoning with facts and data presented. However, nobody is thinking critically 100% of the time. Logical reasoning can be prone to fallacies.

A fallacy is an error in reasoning. When there is a fallacy in the reasoning, conclusions are less credible and can be deemed invalid.

How can critical thinking fallacies be avoided? The first step is to be aware of the possible fallacies that can be committed. This article will highlight the most common logical fallacies.

Common fallacies fall under two categories:

• Fallacies of Relevance
• Fallacies of Unacceptable Premises

For fallacies of relevance, reasons are presented why a certain conclusion is reached, but these reasons may not be entirely true nor significant to the argument.

Under Fallacies of Relevance are:

“Ad Hominem” is Latin for “to the person”. It’s a fallacy that uses attacks on the person making the argument instead of the argument itself.

This is commonly seen in informal arguments where a person’s looks or characteristics are often attacked instead of the argument they’re making.

• Red Herring

This is a fallacy of distraction. It sidetracks the main argument by offering a different issue and then claims that this new issue is relevant to the current one. People who do this aim to divert the audience or another person from their arguments.

• Tu Quoque Fallacy

“Tu Quoque” means “you also” in Latin. This fallacy discredits a person’s argument based on the fact that the person does not practice what he or she preaches.

• Strawman Fallacy

Where a person refutes another person’s argument by presenting a weakened version of the original argument.

• Appeal to Authority

Appeal to Authority fallacy claims that an argument is true because someone who has the “authority” on the subject believes that it’s true. For example, a policeman believes that guns should not have permits. This argument should be accepted as the truth because policemen know what they are talking about. Policemen know how to use guns properly, therefore can be called “experts” to the subject matter.

• Appeal to Popularity or Ad Populum

Much like the previous fallacy, Appeal to Popularity claims that something is true because a lot of people or the majority believe that it’s true. We should steer clear of this fallacy because having 100,000 believers doesn’t make a wrong argument true.

This is commonly used in advertising products. If a good number of people are using the product, why shouldn’t you?

• Appeal to Tradition

This is very similar to appeal to popularity. The only difference is that this fallacy claims that something is true because it has been believed to be true for a long time. It doesn’t depend on how many believe on it, but rather on how long people have believed it.

• Appeal to Ignorance or Argumentum Ad Ignorantiam

This fallacy claims that arguments are true because they have never been proven false or are false because they have never been proven to be true. It suggests that the best solution is to remain ignorant about the situation.

• Appeal to Emotion

As the name suggests, one of the critical thinking fallacies appeal to the emotions of the audience. It aims to evoke feelings like sympathy and affection – both of which can be irrelevant to the original arguments.

• Fallacy of Composition and Division

The fallacy of composition claims that because some parts of the whole are true, that means the whole must be true. The fallacy of division claims that because the whole is true, all parts of the whole must be true.

An example for composition is that just because with Stephen Curry and Kevin Durant are in Golden State and they are good, they will win championships for sure.

An example for division is: “On average, men tend to have longer legs than women. So, this means that Maria has shorter legs than Jerry.” This is false because for all we know, Maria might have longer legs than Jerry.

• Equivocation

The fallacy of equivocation uses key words in an ambiguous way. The key words will mean different when used in one claim and then when used in another claim.

For example, Poppy claims that she has the right to watch whatever she wants to watch. Therefore, it’s just right that she watches television all day.

Fallacies of Unacceptable Premises on the other hand, introduces premises that are somehow relevant, but doesn’t completely support the conclusions for the argument.

Under Fallacies of Unacceptable Premises are:

• False Dichotomy

This fallacy says that there are only two available options and only one of them are correct. In short, it creates a black or white choice. Both cannot be correct, and they are the only possible options.

• Begging the Question

This critical thinking fallacy assumes that the premise under examination is true. It uses this assumed true premise to support other statements.

• Slippery Slope

Slippery Slope claims that when one step is taken, it will snowball into something bigger very quickly. For example, Joe argues that if Maria will stop using straws, the economy will fall very fast.

• Hasty Generalizations

This fallacy creates generalizations from hurried samples. The generalizations might have been made based on a small sample only or a sample that doesn’t entirely represent something properly.

Knowing and studying fallacies is important because this will help people avoid committing them. The presence of critical thinking fallacies weakens and invalidates arguments, so it’s best to steer clear from them.

When someone knows how to identify these fallacies, it will be easier to point out invalid arguments by other people as well. We live in a world where fallacies are often used in arguments – in fact, up to 13 fallacies were already listed and studied in Ancient Greece thousands of years ago.

This is just a testament that these fallacies have existed before and continue to exist now, so we must be aware of them.

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What are Logical Fallacies? | Critical Thinking Basics

Logical fallacies are errors in reasoning or flawed arguments that can mislead or deceive. They often appear plausible but lack sound evidence or valid reasoning, undermining the credibility of an argument. These errors can be categorized into various types, such as ad hominem attacks, strawman arguments, and false cause correlations.

Impact on Critical Thinking, Communication, and Social Interactions

The presence of logical fallacies hampers critical thinking by leading individuals away from rational and evidence-based conclusions. In communication, they can create confusion, weaken the persuasiveness of an argument, and hinder the exchange of ideas.

In social interactions, reliance on fallacious reasoning can strain relationships, impede collaboration, and contribute to misunderstandings.

Benefits of Identifying and Managing Logical Fallacies

Learning to identify logical fallacies enhances critical thinking skills, enabling individuals to analyze arguments more effectively and make informed decisions. In communication, recognizing fallacies empowers individuals to construct more compelling and convincing arguments, fostering clearer and more meaningful exchanges.

Moreover, the ability to manage logical fallacies promotes healthier social interactions by minimizing misunderstandings, encouraging constructive dialogue, and fostering a more intellectually robust and collaborative environment.

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Unit 1: What Is Philosophy?

LOGOS: Critical Thinking, Arguments, and Fallacies

Heather Wilburn, Ph.D

Critical Thinking:

With respect to critical thinking, it seems that everyone uses this phrase. Yet, there is a fear that this is becoming a buzz-word (i.e. a word or phrase you use because it’s popular or enticing in some way). Ultimately, this means that we may be using the phrase without a clear sense of what we even mean by it. So, here we are going to think about what this phrase might mean and look at some examples. As a former colleague of mine, Henry Imler, explains:

By critical thinking, we refer to thinking that is recursive in nature. Any time we encounter new information or new ideas, we double back and rethink our prior conclusions on the subject to see if any other conclusions are better suited. Critical thinking can be contrasted with Authoritarian thinking. This type of thinking seeks to preserve the original conclusion. Here, thinking and conclusions are policed, as to question the system is to threaten the system. And threats to the system demand a defensive response. Critical thinking is short-circuited in authoritarian systems so that the conclusions are conserved instead of being open for revision. [1]

A condition for being recursive is to be open and not arrogant. If we come to a point where we think we have a handle on what is True, we are no longer open to consider, discuss, or accept information that might challenge our Truth. One becomes closed off and rejects everything that is different or strange–out of sync with one’s own Truth. To be open and recursive entails a sense of thinking about your beliefs in a critical and reflective way, so that you have a chance to either strengthen your belief system or revise it if needed. I have been teaching philosophy and humanities classes for nearly 20 years; critical thinking is the single most important skill you can develop. In close but second place is communication, In my view, communication skills follow as a natural result of critical thinking because you are attempting to think through and articulate stronger and rationally justified views. At the risk of sounding cliche, education isn’t about instilling content; it is about learning how to think.

In your philosophy classes your own ideas and beliefs will very likely be challenged. This does not mean that you will be asked to abandon your beliefs, but it does mean that you might be asked to defend them. Additionally, your mind will probably be twisted and turned about, which can be an uncomfortable experience. Yet, if at all possible, you should cherish these experiences and allow them to help you grow as a thinker. To be challenged and perplexed is difficult; however, it is worthwhile because it compels deeper thinking and more significant levels of understanding. In turn, thinking itself can transform us not only in thought, but in our beliefs, and our actions. Hannah Arendt, a social and political philosopher that came to the United States in exile during WWII, relates the transformative elements of philosophical thinking to Socrates. She writes:

Socrates…who is commonly said to have believed in the teachability of virtue, seems to have held that talking and thinking about piety, justice, courage, and the rest were liable to make men more pious, more just, more courageous, even though they were not given definitions or “values” to direct their further conduct. [2]

Thinking and communication are transformative insofar as these activities have the potential to alter our perspectives and, thus, change our behavior. In fact, Arendt connects the ability to think critically and reflectively to morality. As she notes above, morality does not have to give a predetermined set of rules to affect our behavior. Instead, morality can also be related to the open and sometimes perplexing conversations we have with others (and ourselves) about moral issues and moral character traits. Theodor W. Adorno, another philosopher that came to the United States in exile during WWII, argues that autonomous thinking (i.e. thinking for oneself) is crucial if we want to prevent the occurrence of another event like Auschwitz, a concentration camp where over 1 million individuals died during the Holocaust. [3] To think autonomously entails reflective and critical thinking—a type of thinking rooted in philosophical activity and a type of thinking that questions and challenges social norms and the status quo. In this sense thinking is critical of what is, allowing us to think beyond what is and to think about what ought to be, or what ought not be. This is one of the transformative elements of philosophical activity and one that is useful in promoting justice and ethical living.

With respect to the meaning of education, the German philosopher Hegel uses the term bildung, which means education or upbringing, to indicate the differences between the traditional type of education that focuses on facts and memorization, and education as transformative. Allen Wood explains how Hegel uses the term bildung: it is “a process of self-transformation and an acquisition of the power to grasp and articulate the reasons for what one believes or knows.” [4] If we think back through all of our years of schooling, particularly those subject matters that involve the teacher passing on information that is to be memorized and repeated, most of us would be hard pressed to recall anything substantial. However, if the focus of education is on how to think and the development of skills include analyzing, synthesizing, and communicating ideas and problems, most of us will use those skills whether we are in the field of philosophy, politics, business, nursing, computer programming, or education. In this sense, philosophy can help you develop a strong foundational skill set that will be marketable for your individual paths. While philosophy is not the only subject that will foster these skills, its method is one that heavily focuses on the types of activities that will help you develop such skills.

Let’s turn to discuss arguments. Arguments consist of a set of statements, which are claims that something is or is not the case, or is either true or false. The conclusion of your argument is a statement that is being argued for, or the point of view being argued for. The other statements serve as evidence or support for your conclusion; we refer to these statements as premises. It’s important to keep in mind that a statement is either true or false, so questions, commands, or exclamations are not statements. If we are thinking critically we will not accept a statement as true or false without good reason(s), so our premises are important here. Keep in mind the idea that supporting statements are called premises and the statement that is being supported is called the conclusion. Here are a couple of examples:

Example 1: Capital punishment is morally justifiable since it restores some sense of

balance to victims or victims’ families.

Let’s break it down so it’s easier to see in what we might call a typical argument form:

Premise: Capital punishment restores some sense of balance to victims or victims’ families.

Conclusion: Capital punishment is morally justifiable.

Example 2 : Because innocent people are sometimes found guilty and potentially

executed, capital punishment is not morally justifiable.

Premise: Innocent people are sometimes found guilty and potentially executed.

Conclusion: Capital punishment is not morally justifiable.

It is worth noting the use of the terms “since” and “because” in these arguments. Terms or phrases like these often serve as signifiers that we are looking at evidence, or a premise.

Check out another example:

Example 3 : All human beings are mortal. Heather is a human being. Therefore,

Heather is mortal.

Premise 1: All human beings are mortal.

Premise 2: Heather is a human being.

Conclusion: Heather is mortal.

In this example, there are a couple of things worth noting: First, there can be more than one premise. In fact, you could have a rather complex argument with several premises. If you’ve written an argumentative paper you may have encountered arguments that are rather complex. Second, just as the arguments prior had signifiers to show that we are looking at evidence, this argument has a signifier (i.e. therefore) to demonstrate the argument’s conclusion.

So many arguments!!! Are they all equally good?

No, arguments are not equally good; there are many ways to make a faulty argument. In fact, there are a lot of different types of arguments and, to some extent, the type of argument can help us figure out if the argument is a good one. For a full elaboration of arguments, take a logic class! Here’s a brief version:

Deductive Arguments: in a deductive argument the conclusion necessarily follows the premises. Take argument Example 3 above. It is absolutely necessary that Heather is a mortal, if she is a human being and if mortality is a specific condition for being human. We know that all humans die, so that’s tight evidence. This argument would be a very good argument; it is valid (i.e the conclusion necessarily follows the premises) and it is sound (i.e. all the premises are true).

Inductive Arguments : in an inductive argument the conclusion likely (at best) follows the premises. Let’s have an example:

Example 4 : 98.9% of all TCC students like pizza. You are a TCC student. Thus, you like pizza.

Premise 1: 98.9% of all TCC students like pizza

Premise 2: You are a TCC student.

Conclusion: You like pizza. (*Thus is a conclusion indicator)

In this example, the conclusion doesn’t necessarily follow; it likely follows. But you might be part of that 1.1% for whatever reason. Inductive arguments are good arguments if they are strong. So, instead of saying an inductive argument is valid, we say it is strong. You can also use the term sound to describe the truth of the premises, if they are true. Let’s suppose they are true and you absolutely love Hideaway pizza. Let’s also assume you are a TCC student. So, the argument is really strong and it is sound.

There are many types of inductive argument, including: causal arguments, arguments based on probabilities or statistics, arguments that are supported by analogies, and arguments that are based on some type of authority figure. So, when you encounter an argument based on one of these types, think about how strong the argument is. If you want to see examples of the different types, a web search (or a logic class!) will get you where you need to go.

Some arguments are faulty, not necessarily because of the truth or falsity of the premises, but because they rely on psychological and emotional ploys. These are bad arguments because people shouldn’t accept your conclusion if you are using scare tactics or distracting and manipulating reasoning. Arguments that have this issue are called fallacies. There are a lot of fallacies, so, again, if you want to know more a web search will be useful. We are going to look at several that seem to be the most relevant for our day-to-day experiences.

• Inappropriate Appeal to Authority : We are definitely going to use authority figures in our lives (e.g. doctors, lawyers, mechanics, financial advisors, etc.), but we need to make sure that the authority figure is a reliable one.

Things to look for here might include: reputation in the field, not holding widely controversial views, experience, education, and the like. So, if we take an authority figure’s word and they’re not legit, we’ve committed the fallacy of appeal to authority.

Example 5 : I think I am going to take my investments to Voya. After all, Steven Adams advocates for Voya in an advertisement I recently saw.

If we look at the criteria for evaluating arguments that appeal to authority figures, it is pretty easy to see that Adams is not an expert in the finance field. Thus, this is an inappropropriate appeal to authority.

• Slippery Slope Arguments : Slippery slope arguments are found everywhere it seems. The essential characteristic of a slippery slope argument is that it uses problematic premises to argue that doing ‘x’ will ultimately lead to other actions that are extreme, unlikely, and disastrous. You can think of this type of argument as a faulty chain of events or domino effect type of argument.

Example 6 : If you don’t study for your philosophy exam you will not do well on the exam. This will lead to you failing the class. The next thing you know you will have lost your scholarship, dropped out of school, and will be living on the streets without any chance of getting a job.

While you should certainly study for your philosophy exam, if you don’t it is unlikely that this will lead to your full economic demise.

One challenge to evaluating slippery slope arguments is that they are predictions, so we cannot be certain about what will or will not actually happen. But this chain of events type of argument should be assessed in terms of whether the outcome will likely follow if action ‘x” is pursued.

• Faulty Analogy : We often make arguments based on analogy and these can be good arguments. But we often use faulty reasoning with analogies and this is what we want to learn how to avoid.

When evaluating an argument that is based on an analogy here are a few things to keep in mind: you want to look at the relevant similarities and the relevant differences between the things that are being compared. As a general rule, if there are more differences than similarities the argument is likely weak.

Example 7 : Alcohol is legal. Therefore, we should legalize marijuana too.

So, the first step here is to identify the two things being compared, which are alcohol and marijuana. Next, note relevant similarities and differences. These might include effects on health, community safety, economic factors, criminal justice factors, and the like.

This is probably not the best argument in support for marijuana legalization. It would seem that one could just as easily conclude that since marijuana is illegal, alcohol should be too. In fact, one might find that alcohol is an often abused and highly problematic drug for many people, so it is too risky to legalize marijuana if it is similar to alcohol.

• Appeal to Emotion : Arguments should be based on reason and evidence, not emotional tactics. When we use an emotional tactic, we are essentially trying to manipulate someone into accepting our position by evoking pity or fear, when our positions should actually be backed by reasonable and justifiable evidence.

Example 8 : Officer please don’t give me a speeding ticket. My girlfriend broke up with me last night, my alarm didn’t go off this morning, and I’m late for class.

While this is a really horrible start to one’s day, being broken up with and an alarm malfunctioning is not a justifiable reason for speeding.

Example 9 : Professor, I’d like you to remember that my mother is a dean here at TCC. I’m sure that she will be very disappointed if I don’t receive an A in your class.

This is a scare tactic and is not a good way to make an argument. Scare tactics can come in the form of psychological or physical threats; both forms are to be avoided.

• Appeal to Ignorance : This fallacy occurs when our argument relies on lack of evidence when evidence is actually needed to support a position.

Example 10 : No one has proven that sasquatch doesn’t exist; therefore it does exist.

Example 11 : No one has proven God exists; therefore God doesn’t exist.

The key here is that lack of evidence against something cannot be an argument for something. Lack of evidence can only show that we are ignorant of the facts.

• Straw Man : A straw man argument is a specific type of argument that is intended to weaken an opponent’s position so that it is easier to refute. So, we create a weaker version of the original argument (i.e. a straw man argument), so when we present it everyone will agree with us and denounce the original position.

Example 12 : Women are crazy arguing for equal treatment. No one wants women hanging around men’s locker rooms or saunas.

This is a misrepresentation of arguments for equal treatment. Women (and others arguing for equal treatment) are not trying to obtain equal access to men’s locker rooms or saunas.

The best way to avoid this fallacy is to make sure that you are not oversimplifying or misrepresenting others’ positions. Even if we don’t agree with a position, we want to make the strongest case against it and this can only be accomplished if we can refute the actual argument, not a weakened version of it. So, let’s all bring the strongest arguments we have to the table!

• Red Herring : A red herring is a distraction or a change in subject matter. Sometimes this is subtle, but if you find yourself feeling lost in the argument, take a close look and make sure there is not an attempt to distract you.

Example 13 : Can you believe that so many people are concerned with global warming? The real threat to our country is terrorism.

It could be the case that both global warming and terrorism are concerns for us. But the red herring fallacy is committed when someone tries to distract you from the argument at hand by bringing up another issue or side-stepping a question. Politicians are masters at this, by the way.

• Appeal to the Person : This fallacy is also referred to as the ad hominem fallacy. We commit this fallacy when we dismiss someone’s argument or position by attacking them instead of refuting the premises or support for their argument.

Example 14 : I am not going to listen to what Professor ‘X’ has to say about the history of religion. He told one of his previous classes he wasn’t religious.

The problem here is that the student is dismissing course material based on the professor’s religious views and not evaluating the course content on its own ground.

To avoid this fallacy, make sure that you target the argument or their claims and not the person making the argument in your rebuttal.

• Hasty Generalization : We make and use generalizations on a regular basis and in all types of decisions. We rely on generalizations when trying to decide which schools to apply to, which phone is the best for us, which neighborhood we want to live in, what type of job we want, and so on. Generalizations can be strong and reliable, but they can also be fallacious. There are three main ways in which a generalization can commit a fallacy: your sample size is too small, your sample size is not representative of the group you are making a generalization about, or your data could be outdated.

Example 15 : I had horrible customer service at the last Starbucks I was at. It is clear that Starbucks employees do not care about their customers. I will never visit another Starbucks again.

The problem with this generalization is that the claim made about all Starbucks is based on one experience. While it is tempting to not spend your money where people are rude to their customers, this is only one employee and presumably doesn’t reflect all employees or the company as a whole. So, to make this a stronger generalization we would want to have a larger sample size (multiple horrible experiences) to support the claim. Let’s look at a second hasty generalization:

Example 16 : I had horrible customer service at the Starbucks on 81st street. It is clear that Starbucks employees do not care about their customers. I will never visit another Starbucks again.

The problem with this generalization mirrors the previous problem in that the claim is based on only one experience. But there’s an additional issue here as well, which is that the claim is based off of an experience at one location. To make a claim about the whole company, our sample group needs to be larger than one and it needs to come from a variety of locations.

• Begging the Question : An argument begs the question when the argument’s premises assume the conclusion, instead of providing support for the conclusion. One common form of begging the question is referred to as circular reasoning.

Example 17 : Of course, everyone wants to see the new Marvel movie is because it is the most popular movie right now!

The conclusion here is that everyone wants to see the new Marvel movie, but the premise simply assumes that is the case by claiming it is the most popular movie. Remember the premise should give reasons for the conclusion, not merely assume it to be true.

• Equivocation : In the English language there are many words that have different meanings (e.g. bank, good, right, steal, etc.). When we use the same word but shift the meaning without explaining this move to your audience, we equivocate the word and this is a fallacy. So, if you must use the same word more than once and with more than one meaning you need to explain that you’re shifting the meaning you intend. Although, most of the time it is just easier to use a different word.

Example 18 : Yes, philosophy helps people argue better, but should we really encourage people to argue? There is enough hostility in the world.

Here, argue is used in two different senses. The meaning of the first refers to the philosophical meaning of argument (i.e. premises and a conclusion), whereas the second sense is in line with the common use of argument (i.e. yelling between two or more people, etc.).

• Henry Imler, ed., Phronesis An Ethics Primer with Readings, (2018). 7-8. ↵
• Arendt, Hannah, “Thinking and Moral Considerations,” Social Research, 38:3 (1971: Autumn): 431. ↵
• Theodor W. Adorno, “Education After Auschwitz,” in Can One Live After Auschwitz, ed. by Rolf Tiedemann, trans. by Rodney Livingstone (Stanford: Stanford University Press, 2003): 23. ↵
• Allen W. Wood, “Hegel on Education,” in Philosophers on Education: New Historical Perspectives, ed. Amelie O. Rorty (London: Routledge 1998): 302. ↵

LOGOS: Critical Thinking, Arguments, and Fallacies Copyright © 2020 by Heather Wilburn, Ph.D is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License , except where otherwise noted.

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7.4: Fallacies

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• Jim Marteney
• Los Angeles Valley College via ASCCC Open Educational Resources Initiative (OERI)

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A fallacy is an error in reasoning. A fallacy indicates there is a problem with the logic of deductive or inductive reasoning. This differs from a factual error, which is simply being wrong about the facts. To be more specific, a fallacy is an “argument” in which the premises given for the conclusion do not provide the needed degree of support.

A fallacy is a mistake in the way that the final conclusion of the argument, or any intermediate conclusions, are logically related to their supporting premises. When there is a fallacy in an argument, the argument is said to be unsound or invalid

The presence of a logical fallacy in an argument does not necessarily imply anything about the argument’s premises or its conclusion. Both may actually be correct, but the argument is still invalid because the conclusion does not follow from the premises using the inference principles of the argument.

Recognizing fallacies is often difficult, and indeed fallacious arguments often persuade their intended audience. Detecting and avoiding fallacious reasoning will at least prevent adoption of some erroneous conclusions.

Types of Fallacies

Fallacies are usually recognized in isolation, but woven into the context of an argument they may pass unnoticed, unless the critical thinker is on guard against them. Some advocates openly use fallacies in order to exploit an unknowing audience, but many times we use fallacies unintentionally. Many fallacies exist. Here is a few of the most common ones used in everyday argumentation.

False Dilemma The False Dilemma fallacy occurs when an argument offers a false range of choices and requires that you pick one of them. Usually, the False Dilemma fallacy takes this form: Either A or B is true. If A is not true, then B is true. “Either you love me or hate me . ” The range is false because there may be other, unstated choices which would only serve to undermine the original argument. If you agree to pick one of those choices, you accept the premise that those choices are indeed the only ones possible. Seeing something as "black and white” is an example of a false dilemma.

Appeal to Emotion This fallacy is committed when someone manipulates peoples’ emotions in order to get them to accept a claim. More formally, this sort of “reasoning” involves the substitution of various means of producing strong emotions in place of evidence for a claim. Here the attempt is to transfer a positive emotion you have on one thing to the object or belief that is being argued.

This sort of “reasoning” is very common in politics and it serves as the basis for a large portion of modern advertising. Most political speeches are aimed at generating feelings in people, so that these feelings will get them to vote or act a certain way. How many times will you see pictures of American flags in a political commercial? The flag and other traditional images are aimed at getting the audience emotionally involved. In the case of advertising, the commercials are aimed at evoking emotions that will influence people to buy certain products. Beer commercials frequently include people at parties to get the potential consumers excited about the product. In many cases, such speeches and commercials are notoriously free of real evidence.

Non-sequitur The phrase “non-sequitur” is Latin for “it does not follow.” If an inference is made that does not logically follow from the premises of the preceding argument, then the inference is a non-sequitur. For example, “I am wearing my lucky hat today, nothing can go wrong . ” Though the term “non-sequitur” can be used broadly as an informal fallacy to describe any unwarranted conclusion, it is most often used when a statement openly contradicts itself and just makes no sense.

Slippery Slope This fallacy reduces an argument to absurdity by extending it beyond its reasonable limits. This is an abuse of causal reasoning by trying to link events that normally have very little to do with each other. For example: legalizing marijuana will lead to the legalization of cocaine. If you legalize cocaine, you’ll be able to buy crack and every other drug at your local 7-11. In this argument, it is asserted that the legalization of marijuana will eventually lead to purchasing crack at local 7-11’s. Once one accepts the legalization of marijuana, then one is assumed to be on the slippery slope towards the legalization and availability of every other drug. In a Slippery Slope argument, you suggest that a series of events will occur leading to an undesirable conclusion instead of just one step as in Causal Reasoning.

Ad Hominem Translated from Latin to English, “Ad Hominem” means “against the man” or “against the person.” An ad hominem fallacy consists of saying that someone’s argument is wrong purely because of something about the person rather than about the argument itself. You will hear people on the radio and television dismiss comments by people they label as a conservative or a liberal, just because of how they label that person. Merely insulting another person or questioning the credibility of someone does not necessarily constitute an ad hominem fallacy. For this fallacy to exist it must be clear that the purpose of the characterization is to discredit the person offering the argument, in an attempt to invite others to then discount his or her arguments.

The Ad Hominem fallacy was employed by those who wanted to silence 16-year-old Climate Change activist Greta Thunberg. Those who disagreed with her argued that she should be ignored as she is just a child.

Hasty Generalization This fallacy occurs when an arguer bases a conclusion on too few examples, that are not necessarily typical of the conclusion being made. For instance, “My two boyfriends have never shown any concern for my feelings. Therefore, all men are insensitive, selfish, and emotionally uncaring.” Or, “I read about this man who got worms from eating sushi. I always knew that sushi was not good to eat." Without more examples, these arguments can be considered fallacies.

Circular Reasoning The fallacy of circular reasoning is the assertion or repeated assertion of a conclusion, without giving reasons in its support. In other words, supporting a premise with a premise, instead of a conclusion. It may imply that the conclusion is self-evident or rephrase the conclusion to sound like a reason. Circular reasoning creates an illusion of support by simply asserting its conclusion as though it were a reason, or by reasserting the same claim in different words. For example, “Kerosene is combustible; therefore, it burns.” Or, “George Clooney is the best actor we have ever had, because he is the greatest actor of all time.”

Appeal to Ignorance In this fallacy, the arguer claims that something is valid only because it hasn’t been proven false. This fallacy errs by trying to make this argument in a context in which the burden of proof falls on the arguer to show that his or her position is actually accurate, not just that it has not yet been shown false. The argument mistakes lack of evidence for evidence to the contrary. In effect, the argument says, “No one knows it is accurate. Therefore, it is false.” For example, “There is no proof that hand gun legislation will reduce crime. Therefore, outlawing handguns would be a futile gesture." Or, "We have no evidence that God doesn’t exist, therefore, God must exist." Ignorance about something says nothing about its existence or non-existence.

Plato and a Platypus Walk into a Bar

In their book authors Thomas Cathcart and Daniel Klein illustrate logical principles and fallacies using classic jokes. For example, to illustrate the fallacy of post hoc ergo propter hoc, they use the following:

“In general, we’re deceived by post hoc ergo propter hoc because we fail to notice that there’s another cause at work.

A New York boy is being led through the swamps of Louisiana by his cousin. ‘Is it true that an alligator won’t attack you if you carry a flashlight?’ asks the city boy.

His cousin replies, ‘Depends on how fast you carry the flashlight.’

The city boy saw the flashlight as a propter when it was only a prop.” 1

Bandwagon The name “bandwagon fallacy” comes from the phrase “jump on the bandwagon” or “climb on the bandwagon” a bandwagon being a wagon big enough to hold a band of musicians. In past political campaigns, candidates would ride a bandwagon through town, and people would show support for the candidate by climbing aboard the wagon. The phrase has come to refer to joining a cause because of its popularity. For example, trying to convince you that you should do something because everyone else is doing it, is a bandwagon fallacy. "Everybody is buying a Tesla car, so should you."

Post hoc ergo propter hoc The post hoc ergo propter hoc, “after this, therefore because of this,” fallacy is based upon the mistaken notion that simply because one thing happens after another, the first event was a cause of the second event. Post hoc reasoning is the basis for many superstitions and erroneous beliefs.

For example, California earthquakes always happen after unusual weather patterns. Or, Allison always scores a goal when she wears her red and white soccer shoes. Or, I wore my Packers shirt and my Packers team won. I now wear my Packers shirt for every game. These are all, post hoc ergo propter hoc fallacies

Appeal to Pity With this fallacy, the arguer tries to get people to agree with his or her conclusion by evoking pity and sympathy either with the situation or with the situation of some third party. By appealing to people's ability to sympathize with others, a powerful emotive force can be created. Unfortunately, however serious another person's problems are, that does not automatically make their claims any more logical. My sympathy for that situation does not create a reasonable basis for believing his or her claims. For example, "I really need this job since my grandmother is sick" or "I should receive an 'A' in this class. After all, if I don't get an 'A' I won't get the scholarship that I need." These appeals evoke emotions, but are not necessarily logical.

Straw-Man Fallacy The arguer attacks an argument that is different from, and usually weaker than, the opposition’s best argument. To distort or misrepresent an argument one is trying to refute is called the straw man fallacy. In a straw man fallacy, the opponents argument is distorted, misquoted, exaggerated, misrepresented or simply made up. This makes the argument easier to defeat, and can also be used to make opponents look like ignorant extremists. The refutation may appear to be a good one to someone unfamiliar with the original argument.

Logical fallacies are errors of reasoning, errors which may be recognized and corrected by critical thinkers. Fallacies may be created unintentionally, or they may be created intentionally in order to deceive other people. The vast majority of the commonly identified fallacies involve arguments, although some involve explanations, or definitions, or other products of reasoning. Sometimes the term fallacy is used even more broadly to indicate any false belief or cause of a false belief. A fallacy is an argument that sometimes fools human reasoning, but is not logically valid.

In his book, PERSUASION: THEORY AND PRACTICE, Kenneth Anderson writes,

“Logical appeals are powerful forces in persuasion. However, logic alone is rarely sufficient to yield persuasion. Desires and needs of receivers affect and determine what they will accept as logical demonstration. Thus, it is possible for one person to report that he or she is convinced by the logic used while another person remains horrified at the lack of logic presented.” 2

You can have high quality evidence, but lead to incorrect conclusions because your argument has poor reasoning. You always want to create the “soundest” or most logical argument possible. And you also want to examine the logic of others presentations to determine what fallacies might be evident.

• Cathcart, Thomas, and Daniel Klein. Plato and a Platypus Walk into a Bar. New York: Penguin Books, 2007.
• Anderson, Kenneth. Persuasion: Theory and Practice . Boston: American Press, 1983.

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Although there are more than two dozen types and subtypes of logical fallacies, these are the most common forms that you may encounter in writing, argument, and daily life:

Example: Special education students should not be required to take standardized tests because such tests are meant for nonspecial education students.

Example: Two out of three patients who were given green tea before bedtime reported sleeping more soundly. Therefore, green tea may be used to treat insomnia.

• Sweeping generalizations  are related to the problem of hasty generalizations. In the former, though, the error consists in assuming that a particular conclusion drawn from a particular situation and context applies to all situations and contexts. For example, if I research a particular problem at a private performing arts high school in a rural community, I need to be careful not to assume that my findings will be generalizable to all high schools, including public high schools in an inner city setting.

Example: Professor Berger has published numerous articles in immunology. Therefore, she is an expert in complementary medicine.

Example: Drop-out rates increased the year after NCLB was passed. Therefore, NCLB is causing kids to drop out.

Example: Japanese carmakers must implement green production practices, or Japan‘s carbon footprint will hit crisis proportions by 2025.

In addition to claims of policy, false dilemma seems to be common in claims of value. For example, claims about abortion‘s morality (or immorality) presuppose an either-or about when "life" begins. Our earlier example about sustainability (―Unsustainable business practices are unethical.‖) similarly presupposes an either/or: business practices are either ethical or they are not, it claims, whereas a moral continuum is likelier to exist.

Begging the Question/Circular Reasoning

Hasty Generalization

Sweeping Generalization

Non Sequitur

Post Hoc Ergo Propter Hoc

False Dilemma

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A fallacy is a deceptive argument that tries to persuade us to accept the claim that is being advanced, but the reasons in support of the claim are irrelevant or inappropriate. Put differently, a fallacy is an error in reasoning. This differs from a factual error, which is simply being wrong about the facts.

As you will see, some basic background information on fallacies is provided in the suggested online references. In this reading, we shed some more light on the topic. Please remember that while it is important to consult multiple sources, the outcome of the learning process should be that you will be able to recognize inadequacies in arguments. In the section below, we will introduce you to some of the most common fallacies. There are many more types of fallacies that are not covered in this reading, such as the argument from ignorance, appeal to force (or coercion), appeal to the masses, appeal to pity, appeal to spite, shifting the burden of proof, post hoc reasoning, red herring fallacy, affirming the consequent, denying the antecedent, et cetera.

Slippery slope argument

A slippery slope argument leads one from seemingly unimportant and obviously true first premises to calamitous and exaggerated consequences in the conclusion. The “slippery slope” argument format is essentially that if you make any exceptions to a rule, or if you make rules that depend on fine distinctions, pretty soon people will be ignoring the rule or rules entirely because they won’t accept the difference between the exception and everything else. This kind of fallacy is also known as the “give an inch”, or the “crack in the foundation” argument. As the names suggest, the point of departure in this kind of “argument” is that if you allow exceptions to a rule, it creates a slope away from the absoluteness of the rule, down which people will slide further and further until they will not obey the rule at all. In other words, “if you give people an inch, they will take a mile”.

This sort of “reasoning” is fallacious because there is no reason to believe that one event must inevitably follow from another without an argument for such a claim. This is especially clear in cases in which there are a significant number of steps or gradations between one event and another.

Examples of slippery slope arguments:

• “We have to stop the rise in tuition fees! The next thing you know, they’ll be charging $50,000 a semester!”
• “You can never give anyone a break. If you do, they’ll walk all over you.”

Straw man argument

A straw man is someone without substance, who can be easily defeated. Sometimes an opponent will respond to an arguer’s claim by interpreting it in a way that makes it easy for him to knock down the argument. He deliberately ignores the strong points of the argument and attacks a straw man.

For example:

Suppose an arguer claims that nonhuman animals should be accorded rights to protect them from unnecessary suffering because of their sensitivity to pain. A respondent says that this is unacceptable because animals are stupid and therefore would not be able to claim their rights anyway.

Note: This is not what was claimed in the original argument. The opponent attacks a straw man, rather than the real issue.

To identify a straw man argument, you must be familiar enough with the topic in question to recognize when someone is setting up a caricature. Understanding when someone is using this deceptive tactic is the best way to call attention to the weakness of the straw man position.

Begging the question

As you will see in the online references, the fallacy of begging the question occurs when what is supposedly proved by the conclusion of an argument is already assumed to be true in the premises. In other words, the very thing you are trying to prove (your conclusion) is presupposed in the supporting argument (your premises). This is sometimes called “circular reasoning”. Carefully look at the following example:

Deliberately ending the life of a fetus is murder. So it should be clear that abortion is nothing but the illegal killing of the fetus.

The premise of this argument and its conclusion make exactly the same claims, because “abortion” means the “deliberate ending of the life of a fetus” and “murder” means “illegal killing”. The premise gives no support to the conclusion and the argument begs the question.

The fallacies discussed above make it clear why it is important to know how to take apart an argument and examine its constituent parts. By moving beyond the wordiness, it is possible to look at each piece individually and see that we just have the same ideas being presented more than once.

Ad hominem argument

An ad hominem argument attacks the character or circumstances of the person who is making a claim rather than challenging the claim itself.

John Teller’s argument is exactly what one can expect from an atheist like him. In this example, the person is attacked rather than the soundness of her argument.

Note that there are three forms of an ad hominem argument:

• a personal attack on a person’s character
• an attack on the circumstances of the person advancing a claim, and
• an attack on a person’s interests.

False appeal to authority

The fallacy of false appeal to authority takes place when an authority or famous person is quoted in order to get the conclusion the speaker wants rather than providing solid evidence to confirm or refute the claim. The fallacy of false appeal to authority occurs when the “authority” cited is not an expert in the field under discussion.

For example, there is nothing wrong with human cloning. I know this because my medical doctor said that human cloning is morally justified.

The authority cited in this example is an expert in the field of medicine, but he or she is not an expert in the field of ethics. To get his claim accepted, the arguer is committing the fallacy of false appeal to authority because he is quoting an authority who is not, in fact, an authority in the field being discussed.

False dilemma

The fallacy of false dilemma occurs when an “either-or” choice is presented when, in fact, there are more than two alternatives. Here is an example:

Let’s face it, John. Either you are going to be aggressive and show her who’s the boss or you are going to let her walk all over you. I don’t need to tell you what you should do. A man’s gotta do what a man’s gotta do.

Here the fallacy of false dilemma is committed because the arguer presents only two alternatives when, in fact, there are more options available for dealing with the situation at hand. This kind of either-or argument ignores the complexity of the issue.

Hasty generalization

This fallacy occurs when a generalization is made on the basis of insufficient evidence. For example:

Mr. Williams claims: “All good engineers are men because I have not come across any good female engineers”.

Here, Mr Williams commits the fallacy of hasty generalization because he has not looked into all cases of engineers, male or female. The reason Mr. Williams offers for his claim or generalization is insufficient or ill-considered.

We have noted several common fallacies in reasoning. But an argument can fail in many other ways. The point is not to look out for particular fallacies only, but to develop a sense of when an argument is going astray. We can only develop this sense with practice. In subsequent Modules, you will be introduced to the techniques of argument analysis and argument evaluation in detail. But, in the end, successful critical and philosophical reasoning relies on acquiring a knack for recognizing bad arguments.

For additional information on fallacies check out:

• Fallacy Files
• Thou Shalt Not Commit Logical Fallacies

Exercises – Identify the Fallacy

Critical Thinking in Academic Research Copyright © 2022 by Cindy Gruwell and Robin Ewing is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License , except where otherwise noted.

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Wireless Philosophy

Course: wireless philosophy   >   unit 1, fallacies: formal and informal fallacies.

• Formal and Informal Fallacies
• Fallacies: Fallacy of Composition
• Fallacies: Fallacy of Division
• Division and Composition
• Fallacies: Introduction to Ad Hominem
• Fallacies: Ad Hominem
• Ad Hominem, Part 1
• Ad Hominem, Part 2
• Fallacies: Affirming the Consequent
• Fallacies: Denying the Antecedent
• Denying the Antecedent and Affirming the Consequent
• Fallacies: Post Hoc Ergo Propter Hoc
• Post Hoc Ergo Propter Hoc
• Fallacies: Appeal to the People
• Fallacies: Begging the Question
• Begging the Question
• Fallacies: Equivocation
• Fallacies: Straw Man Fallacy
• Fallacies: Slippery Slope
• Fallacies: Red Herring

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Two competing conceptions of fallacies are that they are false but popular beliefs and that they are deceptively bad arguments. These we may distinguish as the belief and argument conceptions of fallacies. Academic writers who have given the most attention to the subject of fallacies insist on, or at least prefer, the argument conception of fallacies, but the belief conception is prevalent in popular and non-scholarly discourse. As we shall see, there are yet other conceptions of what fallacies are, but the present inquiry focuses on the argument conception of fallacies.

Being able to detect and avoid fallacies has been viewed as a supplement to criteria of good reasoning. The knowledge of fallacies is needed to arm us against the most enticing missteps we might take with arguments—so thought not only Aristotle but also the early nineteenth century logicians Richard Whately and John Stuart Mill. But as the course of logical theory from the late nineteenth-century forward turned more and more to axiomatic systems and formal languages, the study of reasoning and natural language argumentation received much less attention, and hence developments in the study of fallacies almost came to a standstill. Until well past the middle of the twentieth century, discussions of fallacies were for the most part relegated to introductory level textbooks. It was only when philosophers realized the ill fit between formal logic, on the one hand, and natural language reasoning and argumentation, on the other, that the interest in fallacies has returned. Since the 1970s the utility of knowing about fallacies has been acknowledged (Johnson and Blair 1993), and the way in which fallacies are incorporated into theories of argumentation has been taken as a sign of a theory’s level of adequacy (Biro and Siegel 2007, van Eemeren 2010).

In modern fallacy studies it is common to distinguish formal and informal fallacies. Formal fallacies are those readily seen to be instances of identifiable invalid logical forms such as undistributed middle and denying the antecedent. Although many of the informal fallacies are also invalid arguments, it is generally thought to be more profitable, from the points of view of both recognition and understanding, to bring their weaknesses to light through analyses that do not involve appeal to formal languages. For this reason it has become the practice to eschew the symbolic language of formal logic in the analysis of these fallacies; hence the term ‘informal fallacy’ has gained wide currency. In the following essay, which is in four parts, it is what is considered the informal-fallacy literature that will be reviewed. Part 1 is an introduction to the core fallacies as brought to us by the tradition of the textbooks. Part 2 reviews the history of the development of the conceptions of fallacies as it is found from Aristotle to Copi. Part 3 surveys some of the most recent innovative research on fallacies, and Part 4 considers some of the current research topics in fallacy theory.

1. The core fallacies

2.1 aristotle, 2.3 arnauld and nicole, 2.6 bentham, 2.7 whately, 3.1 renewed interest, 3.2 doubts about fallacies, 3.3 the informal logic approach to fallacies, 3.4 the formal approach to informal fallacies, 3.5 the epistemic approach to fallacies, 3.6 dialectical/dialogical approaches to fallacies, 4.1 the nature of fallacies, 4.2 the appearance condition, 4.3 teaching, other internet resources, related entries.

Irving Copi’s 1961 Introduction to Logic gives a brief explanation of eighteen informal fallacies. Although there is some variation in competing textbooks, Copi’s selection captured what for many was the traditional central, core fallacies. [ 1 ] In the main, these fallacies spring from two fountainheads: Aristotle’s Sophistical Refutations and John Locke’s An Essay Concerning Human Understanding (1690). By way of introduction, a brief review of the core fallacies, especially as they appear in introductory level textbooks, will be given. Only very general definitions and illustrations of the fallacies can be given. This proviso is necessary first, because, the definitions (or identity conditions) of each of the fallacies is often a matter of contention and so no complete or final definition can be given in an introductory survey; secondly, some researchers wish that only plausible and realistic instances of each fallacy be used for illustration. This also is not possible at this stage. The advantage of the stock examples of fallacies is that they are designed to highlight what the mistake associated with each kind of fallacy is supposed to be. Additional details about some of the fallacies are found in Sections 2 and 3. As an initial working definition of the subject matter, we may take a fallacy to be an argument that seems to be better than it really is.

1. The fallacy of equivocation is an argument which exploits the ambiguity of a term or phrase which has occurred at least twice in an argument, such that on the first occurrence it has one meaning and on the second another meaning. A familiar example is:

The end of life is death. Happiness is the end of life. So, death is happiness.

‘The end of life’ first means ceasing to live, then it means purpose. That the same set of words is used twice conceals the fact that the two distinct meanings undermine the continuity of the reasoning, resulting in a non-sequitur .

2. The fallacy of amphiboly is, like the fallacy of equivocation, a fallacy of ambiguity; but here the ambiguity is due to indeterminate syntactic structure. In the argument:

The police were told to stop drinking on campus after midnight. So, now they are able to respond to emergencies much better than before

there are several interpretations that can be given to the premise because it is grammatically ambiguous. On one reading it can be taken to mean that it is the police who have been drinking and are now to stop it; this makes for a plausible argument. On another reading what is meant is that the police were told to stop others (e.g., students) from drinking after midnight. If that is the sense in which the premise is intended, then the argument can be said to be a fallacy because despite initial appearances, it affords no support for the conclusion.

3 & 4. The fallacies of composition and division occur when the properties of parts and composites are mistakenly thought to be transferable from one to the other. Consider the two sentences:

• Every member of the investigative team was an excellent researcher.
• It was an excellent investigative team.

Here it is ‘excellence’ that is the property in question. The fallacy of composition is the inference from (a) to (b) but it need not hold if members of the team cannot work cooperatively with each other. The reverse inference from (b) to (a)—the fallacy of division—may also fail if some essential members of the team have a supportive or administrative role rather than a research role.

5. The fallacy of begging the question ( petitio principii ) can occur in a number of ways. One of them is nicely illustrated with Whately’s (1875 III §13) example: “to allow everyman an unbounded freedom of speech must always be, on the whole, advantageous to the State; for it is highly conducive to the interest of the Community, that each individual should enjoy a liberty perfectly unlimited, of expressing his sentiments.” This argument begs the question because the premise and conclusion are the very same proposition, albeit expressed in different words. It is a disguised instance of repetition which gives no reason for its apparent conclusion.

Another version of begging the question can occur in contexts of argumentation where there are unsettled questions about key terms. Suppose, for example, that everyone agrees that to murder someone requires doing something that is wrong, but not everyone agrees that capital punishment is a form of ‘murder’; some think it is justified killing. Then, should an arguer gives this argument:

Capital punishment requires an act of murdering human beings. So, capital punishment is wrong.

one could say that this is question-begging because in this context of argumentation, the arguer is smuggling in as settled a question that remains open. That is, if the premise is accepted without further justification, the arguer is assuming the answer to a controversial question without argument.

Neither of these versions of begging the question are faulted for their invalidity, so they are not charged with being non-sequitors like most of the core fallacies; they are, however, attempted proofs that do not transparently display their weakness. This consideration, plus its ancient lineage back to Aristotle, might explain begging the question’s persistent inclusion among fallacies. But, given our allegiance to the modern conception of logic as being solely concerned with the following-from relation, forms of begging the question should be thought of as epistemic rather than logical fallacies.

Some versions of begging the question are more involved and are called circular reasoning. They include more than one inference. Descartes illustrated this kind of fallacy with the example of our belief in the Bible being justified because it is the word of God, and our belief in God’s existence being justified because it is written in the Bible. [ 2 ] The two propositions lead back and forth to each other, in a circle, each having only the support of the other.

6. The fallacy known as complex question or many questions is usually explained as a fallacy associated with questioning. For example, in a context where a Yes or No answer must be given, the question, “Are you still a member of the Ku Klux Klan?” is a fallacy because either response implies that one has in the past been a member of the Klan, a proposition that may not have been established as true. Some say that this kind of mistake is not really a fallacy because to ask a question is not to make an argument.

7. There are a number of fallacies associated with causation, the most frequently discussed is post hoc ergo propter hoc , (after this, therefore because of this). This fallacy ascribes a causal relationship between two states or events on the basis of temporal succession. For example,

Unemployment decreased in the fourth quarter because the government eliminated the gasoline tax in the second quarter.

The decrease in unemployment that took place after the elimination of the tax may have been due to other causes; perhaps new industrial machinery or increased international demand for products. Other fallacies involve confusing the cause and the effect, and overlooking the possibility that two events are not directly related to each other but are both the effect of a third factor, a common cause. These fallacies are perhaps better understood as faults of explanation than faults of arguments.

8. The fallacy of ignoratio elenchi , or irrelevant conclusion, is indicative of misdirection in argumentation rather than a weak inference. The claim that Calgary is the fastest growing city in Canada, for example, is not defeated by a sound argument showing that it is not the biggest city in Canada. A variation of ignoratio elenchi , known under the name of the straw man fallacy, occurs when an opponent’s point of view is distorted in order to make it easier to refute. For example, in opposition to a proponent’s view that (a) industrialization is the cause of global warming, an opponent might substitute the proposition that (b) all ills that beset mankind are due to industrialization and then, having easily shown that (b) is false, leave the impression that (a), too, is false. Two things went wrong: the proponent does not hold (b), and even if she did, the falsity of (b) does not imply the falsity of (a).

There are a number of common fallacies that begin with the Latin prefix ‘ ad ’ (‘to’ or ‘toward’) and the most common of these will be described next.

9. The ad verecundiam fallacy concerns appeals to authority or expertise. Fundamentally, the fallacy involves accepting as evidence for a proposition the pronouncement of someone who is taken to be an authority but is not really an authority. This can happen when non-experts parade as experts in fields in which they have no special competence—when, for example, celebrities endorse commercial products or social movements. Similarly, when there is controversy, and authorities are divided, it is an error to base one’s view on the authority of just some of them. (See also 2.4 below.)

10. The fallacy ad populum is similar to the ad verecundiam , the difference being that the source appealed to is popular opinion, or common knowledge, rather than a specified authority. So, for example:

These days everyone (except you) has a car and knows how to drive; So, you too should have a car and know how to drive.

Often in arguments like this the premises aren’t true, but even if they are generally true they may provide only scant support for their conclusions because that something is widely practised or believed is not compelling evidence that it is true or that it should be done. There are few subjects on which the general public can be said to hold authoritative opinions. Another version of the ad populum fallacy is known as “playing to the gallery” in which a speaker seeks acceptance for his view by arousing relevant prejudices and emotions in his audience in lieu of presenting it with good evidence.

11. The ad baculum fallacy is one of the most controversial because it is hard to see that it is a fallacy or even that it involves bad reasoning. Ad baculum means “appeal to the stick” and is generally taken to involve a threat of injury of harm to the person addressed. So, for example,

If you don’t join our demonstration against the expansion of the park, we will evict you from your apartment; So, you should join our demonstration against the expansion of the park.

Such threats do give us reasons to act and, unpleasant as the interlocutor may be, there seems to be no fallacy here. In labour disputes, and perhaps in international relations, using threats such as going on strike, or cutting off trade routes, are not normally considered fallacies, even though they do involve intimidation and the threat of harm. However, if we change to doxastic considerations, then the argument that you should believe that candidate \(X\) is the one best suited for public office because if you do not believe this you will be evicted from your apartment, certainly is a good instance of irrelevant evidence.

12. The fallacy ad misericordiam is a companion to the ad baculum fallacy: it occurs not when threats are out of place but when appeals for sympathy or pity are mistakenly thought to be evidence. To what extent our sympathy for others should influence our actions depends on many factors, including circumstances and our ethical views. However, sympathy alone is generally not evidence for believing any proposition. Hence,

You should believe that he is not guilty of embezzling those paintings; think of how much his family suffered during the Depression.

Ad misericordiam arguments, like ad baculum arguments, have their natural home in practical reasoning; it is when they are used in theoretical (doxastic) argumentation that the possibility of fallacy is more likely.

13. The ad hominem fallacy involves bringing negative aspects of an arguer, or their situation, to bear on the view they are advancing. There are three commonly recognized versions of the fallacy. The abusive ad hominem fallacy involves saying that someone’s view should not be accepted because they have some unfavorable property.

Thompson’s proposal for the wetlands may safely be rejected because last year she was arrested for hunting without a license.

The hunter Thompson, although she broke the law, may nevertheless have a very good plan for the wetlands.

Another, more subtle version of the fallacy is the circumstantial ad hominem in which, given the circumstances in which the arguer finds him or herself, it is alleged that their position is supported by self-interest rather than by good evidence. Hence, the scientific studies produced by industrialists to show that the levels of pollution at their factories are within the law may be undeservedly rejected because they are thought to be self-serving. Yet it is possible that the studies are sound: just because what someone says is in their self-interest, does not mean it should be rejected.

The third version of the ad hominem fallacy is the tu quoque . It involves not accepting a view or a recommendation because the espouser him- or herself does not follow it. Thus, if our neighbor advises us to exercise regularly and we reject her advice on the basis that she does not exercise regularly, we commit the tu quoque fallacy: the value of advice is not wholly dependent on the integrity of the advisor.

We may finish our survey of the core fallacies by considering just two more.

14. The fallacy of faulty analogy occurs when analogies are used as arguments or explanations and the similarities between the two things compared are too remote to support the conclusion.

If a child gets a new toy he or she will want to play with it; So, if a nation gets new weapons, it will want to use them.

In this example (due to Churchill 1986, 349) there is a great difference between using (playing with) toys and using (discharging) weapons. The former is done for amusement, the latter is done to inflict harm on others. Playing with toys is a benign activity that requires little justification; using weapons against others nations is something that is usually only done after extensive deliberation and as a last resort. Hence, there is too much of a difference between using toys and using weapons to conclude that a nation, if it acquires weapons, will want to use them as readily as children will want to play with their toys.

15. The fallacy of the slippery slope generally takes the form that from a given starting point one can by a series of incremental inferences arrive at an undesirable conclusion, and because of this unwanted result, the initial starting point should be rejected. The kinds of inferences involved in the step-by-step argument can be causal, as in:

You have decided not to go to college; If you don’t go to college, you won’t get a degree; If you don’t get a degree, you won’t get a good job; If you don’t get a good job, you won’t be able to enjoy life; But you should be able to enjoy life; So, you should go to college.

The weakness in this argument, the reason why it is a fallacy, lies in the second and third causal claims. The series of small steps that lead from an acceptable starting point to an unacceptable conclusion may also depend on vague terms rather than causal relations. Lack of clear boundaries is what enables the puzzling slippery slope arguments known as “the beard” and “the heap.” In the former, a person with a full beard eventually becomes beardless as hairs of the beard are removed one-by-one; but because the term ‘beard’ is vague it is unclear at which intermediate point we are to say that the man is now beardless. Hence, at each step in the argument until the final hair-plucking, we should continue to conclude that the man is bearded. In the second case, because ‘heap’ is vague, it is unclear at what point piling scattered stones together makes them a heap of stones: if it is not a heap to begin with, adding one more stone will not make it a heap, etc. In both these cases apparently good reasoning leads to a false conclusion.

Many other fallacies have been named and discussed, some of them quite different from the ones mentioned above, others interesting and novel variations of the above. Some of these will be mentioned in the review of historical and contemporary sources that follows.

2. History of Fallacy Theory

The history of the study of fallacies begins with Aristotle’s work, On Sophistical Refutations . It is among his earlier writings and the work appears to be a continuation of the Topics , his treatise on dialectical argumentation. Although his most extensive and theoretically detailed discussion of fallacies is in the Sophistical Refutations , Aristotle also discusses fallacies in the Prior Analytics and On Rhetoric . Here we will concentrate on summarizing the account given in the Sophistical Refutations . In that work, four things are worth noting: (a) the different conceptions of fallacy; (b) the basic concepts used to explain fallacies; (c) Aristotle’s explanation of why fallacies can be deceptive; and (d) his enumeration and classification of fallacies.

2.1.1 Definitions

At the beginning of Topics (I, i), Aristotle distinguishes several kinds of deductions (syllogisms). They are distinguished first on the basis of the status of their premises. (1) Those that begin from true and primary premises, or are owed to such, are demonstrations. (2) Those which have dialectical premises—propositions acceptable to most people, or to the wise—are dialectical deductions. (3) Deductions that start from premises which only appear to be dialectical, are fallacious deductions because of their starting points, as are (4) those “deductions” that do have dialectical premises but do not really necessitate their conclusions. Other fallacies mentioned and associated with demonstrations are (5) those which only appear to start from what is true and primary ( Top ., I, i 101a5). What this classification leaves out are (6) the arguments that do start from true and primary premises but then fail to necessitate their conclusions; two of these, begging the question and non-cause are discussed in Prior Analytics (II, 16, 17). It is the “fallacious deductions” characterized in (4), however, that come closest to the focus of the Sophistical Refutations . Nevertheless, in many of the examples given what stands out is that the premises are given as answers in dialogue and are to be maintained by the answerer, not necessarily that they are dialectical in the sense of being common opinions. This variation on dialectical deductions Aristotle calls examination arguments ( SR 2 165b4).

2.1.2 The basic concepts

There are three closely related concepts needed to understand sophistical refutations. By a deduction (a syllogism [ 3 ] ) Aristotle meant an argument which satisfies three conditions: it “is based on certain statements made in such a way as necessarily to cause the assertion of things other than those statements and as a result of those statements” ( SR 1 165a1–2). Thus an argument may fail to be a syllogism in three different ways. The premises may fail to necessitate the conclusion, the conclusion may be the same as one of the premises, and the conclusion may not be caused by (grounded in) the premises. The concept of a proof underlying Sophistical Refutations is similar to what is demanded of demonstrative knowledge in Posterior Analytics (I ii 71b20), viz., that the premises must be “true, primary, immediate, better known than, prior to, and causative of the conclusion,” except that the first three conditions do not apply to deductions in which the premises are obtained through questioning. A refutation , Aristotle says, is “a proof of the contradictory” ( SR 6, 168a37)—a proof of the proposition which is the contradictory of the thesis maintained by the answerer. In a context of someone, S , maintaining a thesis, T , a dialectical refutation will consist in asking questions of S , and then taking S ’s answers and using them as the premises of a proof via a deduction of not-T : this will be a refutation of T relative to the answerer ( SR 8 170a13). The concept of contradiction can be found in Categories : it is those contraries which are related such that “one opposite needs must be true, while the other must always be false” (13b2–3). A refutation will be sophistical if either the proof is only an apparent proof or the contradiction is only an apparent contradiction. Either way, according to Aristotle, there is a fallacy. Hence, the opening of his treatise: “Let us now treat of sophistical refutations, that is, arguments which appear to be refutations but are really fallacies and not refutations” ( SR 1 164a20).

2.1.3 The appearance condition

Aristotle observed that “reasoning and refutation are sometimes real and sometimes not, but appear to be real owing to men’s inexperience; for the inexperienced are like those who view things from a distance” ( SR , 1 164b25). The ideas here are first that there are arguments that appear to be better than they really are; and second that people inexperienced in arguments may mistake the appearance for the reality and thus be taken in by a bad argument or refutation. Apparent refutations are primarily explained in terms of apparent deductions: thus, with one exception, Aristotle’s fallacies are in the main a catalogue of bad deductions that appear to be good deductions. The exception is ignoratio elenchi in which, in one of its guises, the deduction contains no fallacy but the conclusion proved only appears to contradict the answerer’s thesis.

Aristotle devotes considerable space to explaining how the appearance condition may arise. At the outset he mentions the argument that turns upon names ( SR 1 165a6), saying that it is the most prolific and usual explanation: because there are more things than names, some names will have to denote more than one thing, thereby creating the possibility of ambiguous terms and expressions. That the ambiguous use of a term goes unnoticed allows the illusion that an argument is a real deduction. The explanation of how the false appearance can arise is in the similarity of words or expressions with different meanings, and the smallness of differences in meaning between some expressions ( SR 7 169a23–169b17).

2.1.4 List and classification

Aristotle discusses thirteen ways in which refutations can be sophistical and divides them into two groups. The first group, introduced in Chapter 4 of On Sophistical Refutations , includes those Aristotle considers dependent on language ( in dictione ), and the second group, introduced in Chapter 5, includes those characterized as not being dependent on language ( extra dictionem ). Chapter 6 reviews all the fallacies from the view point of failed refutations, and Chapter 7 explains how the appearance of correctness is made possible for each fallacy. Chapters 19–30 advise answerers on how to avoid being taken in by sophistical refutations.

The fallacies dependent on language are equivocation, amphiboly, combination of words, division of words, accent and form of expression. Of these the first two have survived pretty much as Aristotle thought of them. Equivocation results from the exploitation of a term’s ambiguity and amphiboly comes about through indefinite grammatical structure. The one has to do with semantical ambiguity, the other with syntactical ambiguity. However, the way that Aristotle thought of the combination and division fallacies differs significantly from modern treatments of composition and division. Aristotle’s fallacies are the combinations and divisions of words which alter meanings, e.g., “walk while sitting” vs. “walk-while-sitting,” (i.e., to have the ability to walk while seated vs. being able to walk and sit at the same time). For division, Aristotle gives the example of the number 5: it is 2 and 3. But 2 is even and 3 is odd, so 5 is even and odd. Double meaning is also possible with those words whose meanings depend on how they are pronounced, this is the fallacy of accent, but there were no accents in written Greek in Aristotle’s day; accordingly, this fallacy would be more likely in written work. What Aristotle had in mind is something similar to the double meanings that can be given to ‘unionized’ and ‘invalid’ depending on how they are pronounced. Finally, the fallacy that Aristotle calls form of expression exploits the kind of ambiguity made possible by what we have come to call category mistakes, in this case, fitting words to the wrong categories. Aristotle’s example is the word ‘flourishing’ which may appear to be a verb because of its ‘ing’ ending (as in ‘cutting’ or ‘running’) and so belongs to the category of actions, whereas it really belongs in the category of quality. Category confusion was, for Aristotle, the key cause of metaphysical mistakes.

There are seven kinds of sophistical refutation that can occur in the category of refutations not dependent on language: accident, secundum quid , consequent, non-cause, begging the question, ignoratio elenchi and many questions.

The fallacy of accident is the most elusive of the fallacies on Aristotle’s list. It turns on his distinction between two kinds of predication, unique properties and accidents ( Top . I 5). The fallacy is defined as occurring when “it is claimed that some attribute belongs similarly to the thing and to its accident” ( SR 5 166b28). What belongs to a thing are its unique properties which are counterpredicable (Smith 1997, 60), i.e., if \(A\) is an attribute of \(B\), \(B\) is an attribute of \(A\). However, attributes that are accidents are not counterpredicates and to treat them as such is false reasoning, and can lead to paradoxical results; for example, if it is a property of triangles that they are equal to two right angles, and a triangle is accidentally a first principle, it does not follow that all first principles have two right angles (see Schreiber 2001, ch. 7).

Aristotle considers the fallacy of consequent to be a special case of the fallacy of accident, observing that consequence is not convertible, i.e., “if \(A\) is, \(B\) necessarily is, men also fancy that, if \(B\) is, \(A\) necessarily is” ( SR 5 169b3). One of Aristotle’s examples is that it does not follow that “a man who is hot must be in a fever because a man who is in a fever is hot” ( SR 5 169b19). This fallacy is sometimes claimed as being an early statement of the formal fallacy of affirming the consequent.

The fallacy of secundum quid comes about from failing to appreciate the distinction between using words absolutely and using them with qualification. Spruce trees, for example, are green with respect to their foliage (they are ‘green’ with qualification); it would be a mistake to infer that they are green absolutely because they have brown trunks and branches. It is because the difference between using words absolutely and with qualification can be minute that this fallacy is possible, thinks Aristotle.

Begging the question is explained as asking for the answer (the proposition) which one is supposed to prove, in order to avoid having to make a proof of it. Some subtlety is needed to bring about this fallacy such as a clever use of synonymy or an intermixing of particular and universal propositions ( Top . VIII, 13). If the fallacy succeeds the result is that there will be no deduction: begging the question and non-cause are directly prohibited by the second and third conditions respectively of being a deduction ( SR 6 168b23).

The fallacy of non-cause occurs in contexts of ad impossibile arguments when one of the assumed premises is superfluous for deducing the conclusion. The superfluous premise will then not be a factor in deducing the conclusion and it will be a mistake to infer that it is false since it is a non-cause of the impossibility. This is not the same fallacy mentioned by Aristotle in the Rhetoric (II 24) which is more akin to a fallacy of empirical causation and is better called false cause (see Woods and Hansen 2001).

Aristotle’s fallacy of many questions occurs when two questions are asked as if they are one proposition. A proposition is “a single predication about a single subject” ( SR 6 169a8). Thus with a single answer to two questions one has two premises for a refutation , and one of them may turn out to be idle, thus invalidating the deduction (it becomes a non-cause fallacy). Also possible is that extra-linguistic part-whole mistakes may happen when, for example, given that something is partly good and partly not-good, the double question is asked whether it is all good or all not-good? Either answer will lead to a contradiction (see Schreiber 2000, 156–59). Despite its name, this fallacy consists in the ensuing deduction, not in the question which merely triggers the fallacy.

On one interpretation ignoratio elenchi is considered to be Aristotle’s thirteenth fallacy, in which an otherwise successful deduction fails to end with the required contradictory of the answerer’s thesis. Seen this way, ignoratio elenchi is unlike all the other fallacies in that it is not an argument that fails to meet one of the criteria of a good deduction, but a genuine deduction that turns out to be irrelevant to the point at issue. On another reading, ignoratio elenchi is not a separate fallacy but an alternative to the language dependent / language independent way of classifying the other twelve fallacies: they all fail to meet, in one way or another, the requirements of a sound refutation.

[A] refutation is a contradiction of one and the same predicate, not of a name but of a thing, and not of a synonymous name but of an identical name, based on the given premises and following necessarily from them (the original point at issue not being included) in the same respect, manner and time. ( SR 5 167a23–27)

Each of the other twelve fallacies is analysed as failing to meet one of the conditions in this definition of refutation ( SR 6). Aristotle seems to favour this second reading, but it leaves the problem of explaining how refutations that miss their mark can seem like successful refutations. A possible explanation is that a failure to contradict a given thesis can be made explicit by adding the negation of the thesis as a last step of the deduction, thereby insuring the contradiction of the thesis, but only at the cost (by the last step) of introducing one of the other twelve fallacies in the deduction.

2.1.5 Different interpretations

I have given only the briefest possible explanation of Aristotle’s fallacies. To really understand them a much longer engagement with the original text and the secondary sources is necessary. The second chapter of Hamblin’s (1970) book is a useful introduction to the Sophistical Refutations , and a defence of the dialectical nature of the fallacies. Hamblin thinks that a dialectical framework is indispensable for an understanding of Aristotle’s fallacies and that part of the poverty of contemporary accounts of fallacies is due to a failure to understand their assumed dialectical setting. This approach to the fallacies is continued in contemporary research by some argumentation theorists, most notably Douglas Walton (1995) who also follows Aristotle in recognizing a number of different kinds of dialogues in which argumentation can occur; Frans van Eemeren and Rob Grootendorst (2004) who combine dialectical and pragmatic insights with an ideal model of a critical discussion; and Jaakko Hintikka who analyses the Aristotelian fallacies as mistakes in question-dialogues (Hintikka 1987; Bachman 1995.) According to Hintikka (1997) it is an outright mistake to think of Aristotle’s fallacies primarily as mistaken inferences, either deductive or inductive. A non-dialogue oriented interpretation of Aristotle fallacies is found in Woods and Hansen (1997 and 2001) who argue that the fallacies (apparent deductions) are basic to apparent refutations, and that Aristotle’s interest in the fallacies extended beyond dialectical contests, as is shown by his interest in them in the Prior Analytics and the Rhetoric (II 24). What gives unity to Aristotle’s different fallacies on this view is not a dialogue structure but rather their dependence on the concepts of deduction and proof. The most thorough recent study of these questions is in Schreiber (2003), who emphasizes Aristotle’s concern with resolving (exposing) fallacies and argues that it is Aristotelian epistemology and metaphysics that is needed for a full understanding of the fallacies in the Sophistical Refutations .

Francis Bacon deserves a brief mention in the history of fallacy theory, not because he made any direct contribution to our knowledge of the fallacies but because of his attention to prejudice and bias in scientific investigation, and the effect they could have on our beliefs. He spoke of false idols (1620, aphorisms 40–44) as having the same relation to the interpretation of nature that fallacies have to logic. The idol of the tribe is human nature which distorts our view of the natural world (it is a false mirror). The idol of the cave is the peculiarity of each individual man, our different abilities and education that affect how we interpret nature. The idols of the theatre are the acquired false philosophies, systems and methods, both new and ancient, that rule men’s minds. These three idols all fall into the category of explanations of why we may misperceive the world. A fourth of Bacon’s idols, the idol of the market place, is the one that comes closest to the Aristotelian tradition as it points to language as the source of our mistaken ideas: “words plainly force and overrule the understanding, and throw all into confusion, and lead men away into numberless empty controversies and idle fancies” (1620, aphorism 43). Although Bacon identifies no particular fallacies in Aristotle’s sense, he opens the door to the possibility that there may be false assumptions associated with the investigation of the natural world. The view of The New Organon is that just as logic is the cure for fallacies, so will the true method of induction be a cure for the false idols.

Antoine Arnauld and Pierre Nicole were the authors of Logic, or the Art of Thinking (1662), commonly known as the Port-Royal Logic. According to Benson Mates (1965, 214) it “is an outstanding early example of the ‘how to think straight’ genre.” The work includes chapters on sophisms, with the justification that “examples of mistakes to be avoided are often more striking than the examples to be imitated” (Bk. III, xix). The Port-Royal Logic does not continue Aristotle’s distinction between fallacies that are dependent on language and those that are not; instead there is a division between sophisms associated with scientific subjects (ibid.)—these are nearly all from the Sophistical Refutations —and those committed in everyday life and ordinary discourse (Bk III, xx). The division is not exclusive, with some of the sophisms fitting both classes.

The Port-Royal Logic includes eight of Aristotle’s original thirteen fallacies, several of them modified to fit the bent to natural philosophy rather than dialectical argumentation. Several kinds of causal errors are considered under the broad heading, non causa pro causa and they are illustrated with reference to scientific explanations that have assigned false causes for empirical phenomena. Also identified as a common fallacy of the human mind is post hoc, ergo propter hoc : “This happened following a certain thing, hence that thing must be its cause” (Bk. III, xix 3). Begging the questions is included and illustrated, interestingly, with examples drawn from Aristotelian science. Two new sophisms are included: one is imperfect enumeration, the error of overlooking an alternative, the other is a faulty (incomplete) induction, what we might call hasty generalization. Although the discussions here are brief, they mark the entry of inductive fallacies into the pool of present day recognized fallacies. Ignoratio elenchi retains its dialogical setting but is extended beyond the mere failure to contradict a thesis, “to attribut[ing] to our adversaries something remote from their views to gain an advantage over them, or to impute to them consequences we imagine can be drawn from their doctrines, although they disavow and deny them” (Bk. III, xix 1). The other Aristotelian fallacies included are accident, combination and division, secundum quid and ambiguity.

The sophisms of everyday life and ordinary discourse are eight in number and two of them, the sophisms of authority and manner, should be noticed. In these sophisms, external marks of speakers contribute to the persuasiveness of their arguments. Although authority is not to be doubted in church doctrines, in matters that God has left to the discernment of humans we can be led away from the truth by being too deferential. Here we find one of the earliest statements of the modern appeal to false authority: people are often persuaded by certain qualities that are irrelevant to the truth of the issue being discussed. Thus there are a number of people who unquestioningly believe those who are the oldest and most experienced, even in matters that depend neither on age nor experience, but only on mental insight (Bk. III, xx 6). To age and experience Arnauld and Nicole add noble birth as an unwarranted source of deference in matters intellectual (Bk. III, xx 7), and towards the end of their discussion they add the sophism of manner, cautioning that “grace, fluency, seriousness, moderation and gentleness” is not necessarily a mark of truth (Bk. III, xx 8). The authors seem to have the rhetorical flourishes of royal courtiers especially in mind.

It is John Locke who is credited with intentionally creating a class of ad -arguments, and inadvertently giving birth to the class of ad -fallacies. In An Essay Concerning Human Understanding (1690), he identified three kinds of arguments, the ad verecundiam , ad ignorantiam , and ad hominem arguments, each of which he contrasted with ad judicium arguments which are arguments based on “the foundations of knowledge and probability” and are reliable routes to truth and knowledge. Locke did not speak of ad -arguments as fallacies—that was left to others to do later—but rather as kinds of arguments “that men, in their reasoning with others, do ordinarily make use of to prevail on their assent; or at least so to awe them as to silence their opposition.” (Bk IV, xvii, 19–22).

Two of the ad arguments have developed beyond how Locke originally conceived them. His characterization of the ad verecundiam is considered the locus classicus of appeal-to-authority arguments. When it is a fallacy it is either on the ground that authorities (experts) are fallible or for the reason that appealing to authority is an abandonment of an individual’s epistemic responsibility. It seems unlikely, however, that Locke thought we should never rely on the expertise and superior knowledge of others when engaged in knowledge-gathering and argumentation. This leads us to consider what kind of authority Locke might have had in mind. In addition to epistemic and legal (command) authority there is also what might be called social authority, demanding respect and deference from others due to one’s higher social standing, something much more a part of seventeenth-century society than it is a part of ours. The language that Locke used in connection with the ad verecundiam , words like ‘eminency’, ‘dignity’, ‘breach of modesty’, and ‘having too much pride’ suggests that what he had in mind was the kind of authority that demands respect for the social standing of sources rather than for their expertise; hence, by this kind of authority a person could be led to accept a conclusion because of their modesty or shame, more so than for the value of the argument (see Goodwin 1998, Hansen 2006). Hence, we understand Locke better when we translate ad verecundiam literally, as “appeal to modesty.”

The argumentum ad hominem , as Locke defined it, has subsequently developed into three different fallacies. His original description was that it was a way “to press a man with consequences drawn from his own principles or concessions.” That is, to argue that an opponent’s view is inconsistent, logically or pragmatically, with other things he has said or to which he is committed. Locke’s observation was that such arguments do not advance us towards truth, but that they can serve to promote agreement or stall disagreement. To argue that way is not a fallacy but an acceptable mode of argumentation. Henry Johnstone (1952) thought it captured the essential character of philosophical argumentation. The modern descendants of the Lockean ad hominem are the abusive ad hominem which is an argument to the effect that a position should not be accepted because of some telling negative property of its espouser; the circumstantial ad hominem , an argument to the effect that someone’s position should be rejected because circumstances suggest that their view is the result of self-interested bias; and finally, the tu quoque ad hominem argument which attempts to deflect a criticism by pointing out that it applies equally to the accuser. Recent scholarship suggests that these post-Lockean kinds of ad hominem arguments are sometimes used fairly, and sometimes fallaciously; but none of them is what Locke described as the argumentum ad hominem .

Ad ignorantiam translates as “appeal to ignorance.” Locke’s characterization of this kind of argument is that it demands “the adversary to admit what they allege as a proof, or to assign a better.” The ignorance in question is comparative, it is not that the opponent has no evidence, it is that s/he has no better evidence. However, the inability of an opponent to produce a better argument is not sufficient reason to think the proponent’s argument must be accepted. Modern versions of this kind of argument take it as a fallacy to infer a proposition to be true because there is no evidence against it (see Krabbe, 1995).

The introduction and discussion of the ad -arguments appears almost as an afterthought in Locke’s Essay . It is found at the end of the chapter, “Of Reason,” in which Locke devotes considerable effort to criticizing syllogistic logic. Reasoning by syllogisms, he maintained, was neither necessary nor useful for knowledge. Locke clearly thought that the three ad -arguments were inferior to ad judicium arguments, but he never used the term ‘fallacy’ in connection with them, although he did use it in connection with errors of syllogistic reasoning.

Was Locke the first to discuss these kinds of arguments? Hamblin (1970, 161–62) and Nuchelmans (1993) trace the idea of ad hominem arguments back to Aristotle, and Locke’s remark that the name argumentum ad hominem was already known has been investigated by Finocchiaro (1974) who finds the term and the argument kind in Galileo’s writings more than a half-century before the Essay Concerning Human Understanding . And Arnauld and Nicole’s discussion of the sophism of authority, that “people speak the truth because they are of noble birth or wealthy or in high office,” which seems to be part of Locke’s ad verecundiam , was most likely known to him. Subsequently more ad -arguments were added to the four that Locke identified (see Watts, and Copi, below).

Isaac Watts in his Logick; or, The Right Use of Reason (1724), furthered the ad -argument tradition by adding three more arguments: argumentum ad fidem (appeal to faith), argumentum ad passiones (appeal to passion), and argumentum ad populum (a public appeal to passions). Like Locke, Watts does not consider these arguments as fallacies but as kinds of arguments. However, the Logick does consider sophisms and introduces “false cause” as an alternative name for non causa pro causa which here, as in the Port-Royal Logic, is understood as a fallacy associated with empirical causation. According to Watts it occurs whenever anyone assigns “the reasons of natural appearances, without sufficient experiments to prove them” (1796, Pt. III, 3 i 4). Another sophism included by Watts is imperfect enumeration or false induction, the mistake of generalizing on insufficient evidence. Also, the term ‘strawman fallacy’ may have its origins in Watts’s discussion of ignoratio elenchi : after having dressed up the opinions and sentiments of their adversaries as they please to make “images of straw”, disputers “triumph over their adversary as though they had utterly confuted his opinions” (1796, Pt. III 3 i 1).

Jeremy Bentham’s Handbook of Political Fallacies (1824) was written in the years leading up to the first Reform Bill (1832). His interest was in political argumentation, particularly in exposing the different means used by parliamentarians and law makers to defeat or delay reform legislation. Hence, it was not philosophy or science that interested him, but political debate. Fallacies he took to be arguments or topics that would through the use of deception produce erroneous beliefs in people (1824, 3). These tactics he (or his editor) divided into four classes: fallacies of authority, danger, delay and confusion. Bentham was aware of the developing ad -fallacies tradition since each of the thirty or so fallacies he described is also labelled as belonging either to the kind ad verecundiam (appeal to shame or modesty), ad odium (appeal to hate or contempt), ad metum (appeal to fear or threats), ad quietem (appeal to rest or inaction), ad judicium , and ad socordiam (appeal to postponement or delay). Most of Bentham’s fallacies have not become staples of fallacy theory but many of them show interesting insights into the motives and techniques of debaters (see e.g., Rudanko’s (2005, 2009) analyses of the ad socordiam ).

Bentham’s Handbook has not taken a central place in the history of fallacy studies (Hamblin 1970, 165–69); nevertheless, it is historically interesting in several respects. It discusses authority at length, identifying four conditions for reliable appeals to authority and maintaining that the failure of any one of them cancels the strength of the appeal. Fallacies of authority in political debate occur when authority “is employed in the place of such relevant arguments as might have been brought forward” (1824, 25). Bentham’s fear is that debaters will resort to “the authority” of traditional beliefs and principles instead of considering the advantages of the reform measures under discussion.

Under the heading “fallacies of danger” Bentham named a number of what he called vituperative fallacies—imputations of bad character, bad motive, inconsistency, and suspicious connections—which have as their common characteristic, “the endeavour to draw aside attention from the measure to the man , in such a way as to cause the latter’s badness to be imputed to the measure he supports, or his goodness to his opposition” (1824, 83). This characterization fits well with the way we have come to think of the ad hominem fallacy as a view disparaged by putting forth a negative characterization of its supporter or his circumstances.

Bentham places the fallacies in the immediate context of debate, identifying ways in which arguers frustrate the eventual resolution of disagreements by using insinuations of danger, delaying tactics, appeals to questionable authorities and, generally, confusing issues. Modern argumentation theorists who hold that any impediment to the successful completion of dialogical discussions is a fallacy, may find that their most immediate precursor was Bentham (see Grootendorst 1997).

Book III of Richard Whately’s Elements of Logic (1826) is devoted to giving an account of fallacies based on “logical principles,”. Whately was instrumental in the revival of interest in logic at the beginning of the nineteenth century and, being committed to deductivism, he maintained that only valid deductive inferences counted as reasoning. Thus, he took every fallacy to belong to either the class of deductive failures (logical fallacies) or the class of non-logical failures (material fallacies).

By ‘fallacy’ Whately meant “any unsound mode of arguing, which appears to demand our conviction, and to be decisive of the question at hand, when in fairness it is not”’ (Bk. III, intro.). The logical fallacies divide into the purely logical and the semi-logical fallacies. The purely logical fallacies are plain violations of syllogistic rules like undistributed middle and illicit process. The semi-logical fallacies mostly trade on ambiguous middle terms and are therefore also logical fallacies, but their detection requires extra-logical knowledge including that of the senses of terms [ 4 ] and knowledge of the subject matter (Bk. III, §2); they include, among others, the fallacies of ambiguity, and division and composition. The non-logical, material fallacies are also divided into two classes: fallacies with premises ‘unduly assumed,’ and fallacies of irrelevant conclusions. Begging the question fits under the heading of a non-logical, material fallacy in which a premise has been unduly assumed, and ignoratio elenchi is a non-logical, material fallacy in which an irrelevant conclusion has been reached. The ad -arguments are all placed under the last division as variants of ignoratio elenchi , but they are said to be fallacies only when they are used unfairly. Whately’s version of the ad hominem argument resembles Locke’s in that it is an ex concessis kind of argument: one that depends on the concessions of the person with whom one is arguing. From the concessions, one might prove that one’s opponent is ‘committed to p, ’ but an attempt to make it seem as if this constitutes a proof of the absolute (non-relative) proposition ‘ p ’ would be a fallacy. This kind of ad hominem fallacy can be seen as falling under the broader ignoratio elenchi category because what is proved is not what is needed.

The creation of the category of non-logical fallacies was not really a break with Aristotle as much as it was a break with what had become the Aristotelian tradition. Aristotle thought that some fallacies were due to unacceptable premises although these are not elaborated in Sophistical Refutations (see section 2.1.1 above). Whately’s creation of the category of non-logical fallacies solved the problem of what to do with begging the question which is not an invalid form of argument, and it also created a place in fallacy taxonomy for the ad -fallacies.

John Stuart Mill’s contribution to the study of fallacies is found in Book V of his comprehensive A System of Logic, Ratiocinative and Inductive , first published in 1843. It stands out most strikingly for placing the study of fallacies within his framework of inductive reasoning, a direct rejection of Whately’s deductivist approach to reasoning and fallacies. Mill held that only inductive reasoning counts as inferring and accordingly he introduces new categories as well as a new classification scheme for fallacies.

Mill drew a division between the moral and the intellectual causes of fallacies. The former are aspects of human nature such as biases and indifference to truth which incline us to make intellectual mistakes. These dispositions are not themselves fallacies. It is the intellectual errors, the actual taking of insufficient evidence as sufficient, that are fallacious. The various ways in which this can happen are what Mill took as the basis for classifying fallacies. “A catalogue of the varieties of evidence which are not real evidence,” he wrote, “is an enumeration of fallacies” (1891, Bk.V iii §1).

Mill divided the broad category of argument fallacies into two groups: those in which the evidence is distinctly conceived and those in which it is indistinctly conceived. Fallacies falling under evidence indistinctly conceived (Bk. V, vii) were further described as fallacies of confusion. These result from an indistinct conception of the evidence leading to a mistaking of its significance and thereby to an unsupported conclusion. Some of the traditional Aristotelian fallacies such as ambiguity, composition and division, petitio principii , and ignoratio elenchi , are placed in this category. Although Mill followed Whately closely in his exposition of the fallacies of confusion, he does not mention any ad -arguments in connection with ignoratio elenchi .

As for the category of fallacies of evidence distinctly conceived, it too is divided. The two sub-classes are fallacies of ratiocination (deduction) and fallacies of induction. The deductive fallacies (Bk.V, vi) are those that explicitly break a rule of the syllogism, such as the three-term rule. But also included are the conversion of universal affirmatives and particular negatives (“All PS” does not follow from “All SP,” and “Some P not S” does not follow from “Some S not P”). Also included in this category is the secundum quid fallacy.

The other sub-class of fallacies distinctly conceived bring out what is distinctive about Mill’s work on the fallacies: that it is the first extensive attempt to deal with fallacies of induction. He divided inductive fallacies into two further groups: fallacies of observation (V, iv) and fallacies of generalization (Bk. V, v). Fallacies of observation can occur either negatively or positively. Their negative occurrence consists in non-observation in which one has overlooked negatively relevant evidence. This is similar to what the Port-Royal Logic considered a faulty enumeration, and one of Mill’s examples is the continued faith that farmers put in the weather forecasts found in almanacs despite their long history of false predictions. Observation fallacies occur positively when the mistake is based on something that is seen wrongly, i.e., taken to be something that it is not. Such mal-observations occur when we mistake our inferences for facts, as in our inference that the sun rises and sets (Bk. V, iv, 5).

Fallacies of generalization, the other branch of inductive fallacies, result from mistakes in the inductive process which can happen in several ways. As one example, Mill pointed to making generalizations about what lies beyond our experience: we cannot infer that the laws that operate in remote parts of the universe are the same as those in our solar system (Bk. V, v, 2). Another example is mistaking empirical laws stating regularities for causal laws—his example was because women as a class have not hitherto equalled men as a class, they will never be able to do so (Bk. V, v, 4). Also placed in the category of fallacies of generalization is post hoc ergo propter hoc , which tends to single out a single cause when there are in reality many contributing causes (Bk. V, v, 5). Analogical arguments are identified as a false basis for generalizations; they are “at best only admissible as an inconclusive presumption, where real proof is unattainable” (Bk. V, v, 6).

Mill also included what he calls fallacies of inspection, or a priori fallacies (Bk. V, iii) in his survey of fallacies. These consist of non-inferentially held beliefs, so they fit the belief conception of fallacies rather than the argument conception. Among Mill’s examples of a priori fallacies are metaphysical assumptions such as that distinctions of language correspond to distinctions in nature, and that objects cannot affect each other at a distance. Even the belief in souls or ghosts is considered an a priori fallacy. Such beliefs will not withstand scrutiny, thought Mill, by the inductive method strictly applied.

A System of Logic is the most extensive work on fallacies since Aristotle’s Sophistical Refutations . Mill’s examples are taken from a wide range of examples in science, politics, economics, religion and philosophy. His classificatory scheme is original and comprehensive. Frederick Rosen (2006) argues that Mill’s pre-occupation with the detection and prevention of fallacies is part of what motivates the celebrated second chapter of On Liberty . Despite these considerations, the Logic is not much referenced by fallacy theorists.

Irving Copi’s Introduction to Logic —an influential text book from the mid-twentieth century—defines a fallacy as “a form of argument that seems to be correct but which proves, upon examination, not to be so.” (1961, 52) The term ‘correct’ is sufficiently broad to allow for both deductive invalidity, inductive weakness, as well as some other kinds of argument failure. Of the eighteen informal fallacies Copi discusses, eleven can be traced back to the Aristotelian tradition, and the other seven to the burgeoning post-Lockean ad -fallacy tradition.

The first division in Copi’s classification is between formal and informal fallacies. Formal fallacies are invalid inferences which “bear a superficial resemblance” to valid forms of inference, so these we may think of as deductive fallacies. They include affirming the consequent, denying the antecedent, the fallacy of four terms, undistributed middle, and illicit major. Informal fallacies are not characterized as resembling formally valid arguments; they gain their allure some other way. One division of informal fallacies is the fallacies of relevance which are “errors in reasoning into which we may fall because of carelessness and inattention to our subject matter” (1961, 53). This large class of fallacies includes accident, converse accident, false cause, petitio principii , complex question, ignoratio elenchi , ad baculum , ad hominem abusive, ad hominem circumstantial, ad ignorantiam , ad misericordiam , ad populum , and ad verecundiam . The other division of informal fallacies is called fallacies of ambiguity and it includes equivocation, amphiboly, accent, composition and division.

It seems that Copi took Whately’s category of semi-logical fallacies and moved them under a new heading of ‘informal fallacies,’ presumably for the reason that extra-logical knowledge is needed to uncover their invalidity. This has the result that the new wide category of informal fallacies is a mixed bag: some of them are at bottom logical failures (equivocation, composition, ad misericordiam ) and some are logically correct but frustrate proof (begging the question, ignoratio elenchi ). [ 5 ] Copi’s classification, unlike Whately’s which sought to make a distinction on logical grounds, may be seen as based on three ways that fallacies resemble good arguments: formal fallacies have invalid forms that resemble valid forms, fallacies of ambiguity resemble good arguments through the ambiguity of terms, and fallacies of relevance exploit psychological (non-logical) associations. Hence, we may think of Copi’s divisions as between logical, semantic and psychological fallacies.

Copi’s treatment of the fallacies is a fair overview of the traditional list of fallacies, albeit he did not pretend to do any more than give an introduction to existing fallacy-lore for beginning logic students. Hamblin (1970, ch. 1) criticized Copi’s work, along with that of several others, and gave it the pejorative name, “the standard treatment of fallacies.” His criticisms rang true with many of his readers, thereby provoking contempt for the traditional treatment of fallacies as well as stimulating research in what we may call the new, or post-Hamblin, era, of fallacy studies. Let us next consider some of these developments.

3. New approaches to fallacies

A common complaint since Whately’s Elements of Logic is that our theory and teaching of fallacies are in want of improvement—he thought they should be put on a more logical footing to overcome the loose and vague treatments others had proffered.

It is on Logical principles therefore that I propose to discuss the subject of Fallacies. … the generality of Logical writers have usually followed so opposite a plan. Whenever they have to treat of anything that is beyond the mere elements of Logic, they totally lay aside all reference to the principles they have been occupied in establishing and explaining, and have recourse to a loose, vague, and popular kind of language … [which is] … strangely incongruous in a professional Logical treatise. (1875, III, intro.)

Charles Hamblin’s 1970 book, Fallacies , revives Whately’s complaint. We may view Fallacies as the dividing line between traditional approaches to the study of fallacies and new, contemporary approaches. At the time of its publication it was the first book-length work devoted to fallacies in modern times. The work opens with a critique of the standard treatment of fallacies as it was found in mid-twentieth century textbooks; then, in subsequent chapters, it takes a historical turn reviewing Aristotle’s approach to fallacies and exploring the tradition it fostered (as in the previous section of this entry). Other historically-oriented chapters include one on the Indian tradition, and one on formal fallacies. Hamblin’s more positive contributions to fallacy studies are concentrated in the book’s later chapters on the concept of argument, formal dialectics, and equivocation.

What Hamblin meant by “the standard treatment of fallacies” was:

The typical or average account as it appears in the typical short chapter or appendix of the average modern textbook. And what we find in most cases, I think it should be admitted, is as debased, worn-out and dogmatic a treatment as could be imagined—incredibly tradition bound, yet lacking in logic and in historical sense alike, and almost without connection to anything else in modern Logic at all. (1970, 12)

Let us consider what came before Hamblin as the traditional approach to fallacies and what comes after him as new approaches. The new approaches (since the 1970’s) show a concern to overcome Hamblin’s criticisms, and they also vie with each to produce the most defensible alternative to the traditional approach. One thing that nearly all the new approaches have in common is that they reject what Hamblin presents as the nearly universally accepted definition of “fallacy” as an argument “that seems to be valid but is not so” (1970, 12). Although this definition of fallacy is not nearly as widely accepted as Hamblin intimated (see Hansen 2002), others have taken to calling it “the standard definition of fallacies” and for convenience we can refer to it as SDF. SDF has three necessary conditions: a fallacy (i) is an argument, (ii) that is invalid, and (iii) appears to be valid. These can be thought of as the argument condition, the invalidity condition and the appearance condition. All three conditions have been brought into question.

Maurice Finocchiaro continued Hamblin’s criticism of the modern textbook treatment of fallacies, observing that they contain very few examples of actual fallacies, leading him to doubt the validity of ‘fallacy’ as a genuine logical category. Although he allows that errors in reasoning are common in real life, he thinks that “types of logically incorrect arguments”—fallacies—are probably not common (1981, 113). For that reason Finocchiaro prefers to speak of fallacious arguments —by which he means arguments in which the conclusion fails to follow from the premises—rather than fallacies (1987, 133). He further distances himself from SDF by not considering the appearance condition.

Finocchiaro distinguishes six ways in which arguments can be fallacious. (1) Formal fallaciousness is simply the case where the conclusion does not follow validly from the premises; this type of error can be demonstrated by producing a suitable analogous counter-example in which the premises are true and the conclusion is false. (2) Explanatory fallaciousness occurs when a specified conclusion follows with no more certainty from the given premises than does a rival conclusion; it occurs most often in the context of proposing explanatory hypotheses. (3) Presuppositional fallaciousness occurs in those cases where an argument depends on a false presupposition; this kind of fallaciousness is demonstrated by making a sound argument showing the presupposition to be false. (4) Positive fallaciousness occurs when the given premises, complemented by other propositions taken as true, are shown to support a conclusion inconsistent with the given conclusion. (5) Semantical fallaciousness results from the ambiguity of terms; the conclusion will follow if the sense given to the term in the premises makes the premises false, but if the other sense is ascribed to the term, making the premises true, the conclusion does not follow (it becomes an instance of formal fallaciousness). (6) Finally, Finocchiaro singles out persuasive fallaciousness , in which the conclusion does not follow from the premises because it is the same as one of the premises. As a test of completeness of this six-fold division of fallaciousness, Finocchiaro (1987) observes that it is adequate to classify all the kinds of errors which Galileo found in the arguments of the defenders of the geocentric view of the solar system.

Gerald Massey (1981) has voiced a strong objection to fallacy theory and the teaching of fallacies. He argues that there is no theory of invalidity—no systematic way to show that an argument is invalid other than to show that it has true premises and a false conclusion (1981, 164). Hence, there is an asymmetry between proving arguments valid and proving them invalid: they are valid if they can be shown to be an instance of a valid form, but they are not proved invalid by showing that they are an instance of an invalid form, because both valid and invalid arguments instantiate invalid forms. Thus, showing that a natural language argument is an instance of an invalid form does not preclude the possibility that it is also an instance of a valid form, and therefore valid. Since upholders of SDF maintain that fallacies are invalid arguments, Massey’s asymmetry thesis has the consequence that no argument can be convicted of being a fallacy on logical grounds. [ 6 ]

The informal logic approach to fallacies is taken in Johnson and Blair’s Logical Self-Defence , a textbook first published in 1977. It was prompted in part by Hamblin’s indictment of the standard treatment and it further develops an initiative taken by Kahane (1971) to develop university courses that were geared to everyday reasoning. Johnson and Blair’s emphasis is on arming students to defend themselves against fallacies in everyday discourse, and a fundamental innovation is in their conception of a good argument. In place of a sound argument—a deductively valid argument with true premises—Johnson and Blair posit an alternative ideal of a cogent argument , one whose premises are acceptable, relevant to and sufficient for its conclusion. Acceptability replaces truth as a premise requirement, and the validity condition is split in to two different conditions, premise relevance and premise sufficiency. Acceptability is defined relative to audiences—the ones for whom arguments are intended—but the other basic concepts, relevance and sufficiency, although illustrated by examples, remain as intuitive, undefined concepts (see Tindale, 2007). Premise sufficiency (strength) is akin to probability in that it is a matter of degree but Johnson and Blair do not pursue giving it numerical expression.

The three criteria of a cogent argument, individually necessary and jointly sufficient, lead to a conception of fallacy as “any argument that violates one of the criteria of good argument … and is committed frequently in argumentative discourse” (1993, 317–18). This shares only one condition with SDF: that a fallacy is an argument. (Deductive) validity is replaced with the broader concept sufficiency, and the appearance condition is not included. Johnson (1987) argued that the appearance condition makes the occurrence of fallacies too subjective since how things appear may vary from perceiver to perceiver, and it should therefore be replaced by a frequency requirement. To be a fallacy, a mistake must occur with sufficient frequency to be worth our attention.

The adoption of the concept of a cogent argument as an ideal has several consequences. The category of fallacies with problematic premises (reminiscent of Whately’s “premises unduly assumed”) shows a concern with argument evaluation over and beyond logical or inference evaluation, drawing the informal logic approach away from purely logical concerns towards an epistemic conception of fallacies. Having both sufficiency and relevance as criteria (instead of the single validity criterion) has the benefit of allowing the making of nuanced judgments about the level of premise support: for example, we might say that an argument’s premises, although insufficient, are nevertheless positively relevant to the conclusion. Irrelevant premise fallacies are those with no premise support at all, whereas insufficient premise fallacies are those in which there is some support, but not enough of it. The informal logicians’ conception of fallacies is meant to be broader and more suitable to natural language argumentation than would be a conception tied only to deductive invalidity.

Johnson and Blair concern themselves exclusively with informal fallacies. Many of the familiar Aristotelian fallacies that are part of the standard treatment are missing from their inventory (e.g., accident, composition and division) and the ones retained find themselves in new categories: begging the question and ambiguity are together under the heading of Problematic Premise; appeals to authority and popularity are placed under the heading of Hasty Conclusion fallacies; ad hominem is among the fallacies that belong in the third category, Fallacies of Irrelevant Reason. This new list of fallacies has a different bent than many earlier lists, being more geared to deal with arguments in popular, everyday communication than philosophical or scientific discourse; this is evident both by the omission of some of the traditional fallacies as well as by the introduction of new ones, such as dubious assumption, two wrongs, slippery slope, and faulty analogy.

The kinds of mistakes one can make in reasoning are generally thought to be beyond enumeration and, hence, it has been maintained that there can be no complete stock of fallacies that will guard against every kind of mistake. Johnson and Blair’s approach is responsive to this problem in that it allows the names of the classes of fallacies — ‘unacceptable premise,’ ‘irrelevant reason’ and ‘hasty conclusion’ — to stand for fallacies themselves, fallacies broad-in-scope; i.e., to serve “both as general principles of organization, and as back-ups to fill in any gaps between specific labels belonging within each genus” (1993, 52). Hence, any violation of one of the criteria of a cogent argument can be considered a fallacy.

In addition to this alternative theoretical approach to fallacies built on the three criteria of a cogent argument—an approach also taken up by others [ 7 ] —informal logic’s contribution to fallacy studies lies in its attempts to provide better analyses of fallacies, a programme pursued by a large number of researchers, including Govier (1982) on the slippery slope, Wreen (1989) on the ad baculum , Walton (1991) on begging the question, Brinton (1995) on the ad hominem , Freeman (1995) on the appeal to popularity, and Pinto (1995) on post hoc ergo propter hoc .

John Woods also despairs of the standard treatment but he sees in it something of importance; namely that the fallacies most often reviewed in introductory level logic textbooks “are a kind of caricature of their associated improprieties, which lie deeply imbedded in human practice” (Woods 1992, 25). The fallacies are then behavioural symptoms of kinds of irrationality to which humans are highly susceptible, and that makes them an important subject for study because they say something about human nature. Therefore, the problem with the standard treatment, according to Woods, is not that it is a misdirected research programme, but rather that it has been poorly carried out, partly because logicians have failed to appreciate that a multi-logical approach is necessary to understand the variety of fallacies. This idea, pursued jointly by Woods and Douglas Walton (1989), is that, for many of the fallacies standard formal logic is inadequate to uncover the unique kind of logical mistakes in question—it is too coarse conceptually to reveal the unique character of many of the fallacies. To get a satisfactory analysis of each of the fallacies they must be matched with a fitting logical system, one that has the facility to uncover the particular logical weakness in question. Inductive logic can be employed for analysis of hasty generalization and post hoc ergo propter hoc ; relatedness logic is appropriate for ignoratio elenchi ; plausible reasoning theory for the ad verecundiam , and dialectical game theory for begging the question and many questions. Woods (1992, 43) refers to this approach to studying the fallacies as methodological pluralism. Thus, like the informal logicians, there is here an interest in getting the analyses of each of the fallacies right, but the Woods and Walton approach involves embracing formal methods, not putting them aside.

Woods (2013) has continued his research on fallacies, most recently considering them in the context of what he calls a naturalized logic (modelled on Quine’s naturalized epistemology). The main point of this naturalizing move is that a theory of reasoning should take into account the abilities and motivations of reasoners. Past work on the fallacies has identified them as failing to satisfy the rules of either deductive or inductive logic, but Woods now wants to consider the core fallacies in light of what he calls third-way reasoning (comparable to non-monotonic reasoning), an account of the cognitive practices that closely resemble our common inferential practices. From the perspective of third-way reasoning the “rules” implicit in the fallacies present themselves as heuristic directives to reasoners rather than as fallacies; hence, it may be that learning from feedback (having errors corrected) is less trouble than learning the rules to avoid fallacies in the first place (Woods 2013, p. 215). Woods illustrates his point by recalling many of the fallacies he originally identified in his 1992 paper, and subjecting them to this revised model of analysis thereby overturning the view that these types of argument are always to be spurned.

SDF may be seen as closely tied to the logical approach to fallacies—the fault in arguments it singles out is their deductive invalidity. But this conception of fallacies turns out to be inadequate to cover the variety of the core fallacies in two ways: it is too narrow because it excludes begging the question which is not invalid, and it is too wide because it condemns good but non-deductive arguments as fallacies (given that they also satisfy the appearance condition) because they are invalid. Even if we replace the invalidity condition in SDF with some less stringent standard of logical weakness which could overcome the “too wide” problem, it would still leave the difficulty of accounting for the fallacy of begging the question unsolved.

Siegel and Biro (1992, 1995) hold an epistemic account of fallacies, contrasting their view with dialectical/rhetorical approaches, because matters extraneous to arguments, such as being a practice that leads to false beliefs or not being persuasive, are not in their view a sufficient condition to make an argument a fallacy. They take the position that “it is a conceptual truth about arguments that their central … purpose is to provide a bridge from known truths or justified beliefs to as yet unknown … truths or as yet unjustified beliefs” (1992, 92). Only arguments that are “epistemically serious” can accomplish this; that is, only arguments that satisfy the extra-formal requirement that premises are knowable independently of their conclusions, and are more acceptable epistemically than their conclusions, can fulfill this function. A purely logical approach to argument will not capture this requirement because arguments of the same valid form, but with different contents, may or may not be epistemically serious, depending on whether the premises are epistemically acceptable relative to the conclusion.

Modifying Biro’s (1977, 265–66) examples we can demonstrate how the requirement of epistemic seriousness plays out with begging the question. Consider these two arguments:

All men are mortal; Obama is a man; So, Obama is mortal.

All members of the committee are old Etonians; Fortesque is a member of the committee; Fortesque is an old Etonian.

In the first argument the premises are knowable independently of the conclusion. The major premise can be deduced from other universal premises about animals, and the minor premise, unlike the conclusion which must be inferred, can be known by observation. Hence, this argument does not beg the question. However, in the second argument (due to Biro, 1977) given the minor premise, the major cannot be known to be true unless the conclusion is known to be true. Consequently, on the epistemic approach to fallacies taken by Biro and Siegel, the second argument, despite the fact that it is valid, is non-serious, it begs the question, and it is a fallacy. If there was some independent way of knowing whether the major premise was true, such as that it was a bylaw that only old Etonians could be committee members, the argument would be a serious one, and not beg the question.

Biro and Siegel’s epistemic account of fallacies is distinguishable in at least three ways. First, it insists that the function of arguments is epistemic, and therefore anything that counts as a fallacy must be an epistemic fault, a breaking of a rule of epistemic justification. But since logical faults are also epistemic faults, the epistemic approach to fallacies will include logical fallacies, although these must also be explicable in terms of epistemic seriousness. Second, since the epistemological approach does not insist that all justification must be deductive, it allows the possibility of their being fallacies (as well as good arguments) by non-deductive standards, something precluded by SDF. Finally, we notice that the appearance condition is not considered a factor in this discussion of fallacies.

Ulrike Hahn and Mike Oaksford (2006a, 2006b) see themselves as contributing to the epistemic approach to fallacy analysis by developing a probabilistic analysis of the fallacies. It is part of their programme for a normative theory of natural language argumentation. They are motivated by what they perceive as the shortcomings in other approaches. The logical (deductive) approach falls short in that it simply divides arguments into valid and invalid arguments thereby failing to appreciate that natural language arguments come in various degrees of strength. The alternative approaches to fallacies, given by procedural (dialectical) and consensual accounts, they criticize on the basis that they fail to address the central problem raised by the fallacies: that of the strength of the reason-claim complex. In Hahn and Oaksford’s view the strength or weakness of the classical fallacies (they are concerned mostly with the post-Aristotelian ones) is not a result of their structure or their context of use. It is instead a matter of the relationship between the evidence and the claim (the contents of the premises and the conclusion). Evaluation of this relationship is thought to be best captured by a probabilistic Bayesian account; accordingly, they adapt Bayes’ theorem to arguments evaluation with the proviso that the probabilities are subjective degrees of belief, not frequencies. “An argument’s strength,” they write, “is a function of an individual’s initial level of belief in the claim, the availability and observation of confirmatory (or disconfirmatory) evidence, and the existence and perceived strength of competing hypotheses” (Corner, et al. 1145). With Korb (2003) they view a fallacy as an argument with a low probability on the Bayesian model.

Since the variance in input probabilities will result in a range of outputs in argument strength, this probabilistic approach has the potential to assign argument strengths anywhere between 0 and 1, thereby allowing that different tokens of one argument type can vary greatly in strength, i.e., some will be fallacies and others not. Also, and this seems to concur with our experience, different arguers may disagree on the strength of the same arguments since they can differ in the assignments of the initial probabilities. Hahn and Oaksford also claim as advantages for their normative theory that it gives guidance for persuasion since it takes into account the initial beliefs of audiences. Moreover, their approach contributes to the study of belief change; that is, to what extent our confidence in the conclusion changes with the availability of new evidence.

Some of the most active new researchers on fallacies take a dialectical and/or dialogical approach. This can be traced back to Hamblin (1970, ch. 8) and Lorenzen’s (1969) dialogue theory. The panacea for fallacies that Whately recommended was more logic; Hamblin, however, proposed a shift from the logical to the dialectical perspective.

[W]e need to extend the bounds of Formal Logic; to include features of dialectical contexts within which arguments are put forward. To begin with, there are criteria of validity of argument that are additional to formal ones: for example, those that serve to proscribe question-begging. To go on with, there are prevalent but false conceptions of the rules of dialogue, which are capable of making certain argumentative moves seem satisfactory and unobjectionable when, in fact, they conceal and facilitate dialectical malpractice. (Hamblin 1970, 254)

The proposal here is to shift the study of fallacies from the contexts of arguments to the contexts of dialogues (argumentation), formulate rules for reasonable dialogue activity, and then connect fallacies to failures of rule-following. Barth and Martens’s paper (1977), which studied the argumentum ad hominem by extending Lorenzen’s dialogue tableaux method to include the definitions of the concepts “line of attack” and “winning strategy,” leads to a conception of fallacies as either failures to meet one of the necessary conditions of rational dialogical argumentation, or failures to satisfy sufficient conditions as specified by production rules of the dialogical method (1977, 96).

The Barth and Martens paper is a bridge between the earlier (quasi-) formal and subsequent informal dialectical theories, and is explicitly acknowledged as a major influence by the Pragma-dialectical theory, the brainchild of Frans van Eemeren and Rob Grootendorst (1984). Rather than beginning from a logical or epistemological perspective they start with the role of argumentation in overcoming interpersonal disagreements. The Pragma-dialecticians propose that inter-personal argumentation can be analysed as two-party-discussions having four analytical stages: a confrontation stage in which the participants become aware of the content of their disagreement; an opening stage in which the parties agree (most likely implicitly) to shared starting points and a set of rules to govern the ensuing discussion; an argumentation stage wherein arguments and doubts about arguments are expressed and recognized; and a final stage in which a decision about the initial disagreement is made, if possible, based on what happened in the argumentation stage.

The Pragma-dialectical theory stipulates a normative ideal of a critical discussion which serves both as a guide to the reconstruction of natural language argumentation, as well as a standard for the evaluation of the analysed product of reconstruction. A set of ten rules has been proposed as constitutive of the critical-discussion ideal, and the proponents of the theory believe that rational arguers would accept them. If followed by both parties to the disagreement, the rules constrain the argumentation decision procedure such that any resolution reached will be deemed reasonable, and “every violation of any of the rules of the discussion procedure for conducting a critical discussion” will be a fallacy (2004, 175). The rules range over all the four stages of argumentation: at the confrontation stage there is a rule which says one may not prevent the other party from expressing their view; for the argumentation stage there is a rule which requires argumentation to be logically strong and in accord with one or another of three general argumentation schemes; at the closing stage there is a rule that the participants themselves are to decide which party was successful based on the quality of the argumentation they have made: if the proponent carries the day, the opponent should acknowledge it, and vice versa .

The Pragma-dialectical theory proposes that each of the core fallacies can be assigned a place as a violation of one of the rules of a critical discussion. For example, the ad baculum fallacy is a form of intimidation that violates the rule that one may not attempt to prevent one’s discussion partner from expressing their views; equivocation is a violation of the rule that formulations in arguments must be clear and unambiguous; post hoc ergo propter hoc violates the rule that arguments must be instances of schemes correctly applied. Moreover, on this theory, since any rule violation is to count as a fallacy this allows for the possibility that there may be hitherto unrecognized “new fallacies.” Among those proposed are declaring a standpoint sacrosanct because that breaks the rule against the freedom to criticize points of view, and evading the burden of proof which breaks the rule that you must defend your standpoint if asked to do so (see van Eemeren 2010, 194).

Clearly not all the rules of critical discussions apply directly to arguments. Some govern other goal-frustrating moves which arguers can make in the course of settling a difference of opinion, such as mis-allocating the burden of proof, asking irrelevant questions, suppressing a point of view, or failing to clarify the meaning of one’s argumentation. In short, the Pragma-dialectical rules of a critical discussion are not just rules of logic or epistemology, but rules of conduct for rational discussants, making the theory more like a moral code than a set of logical principles. Accordingly, this approach to fallacies rejects all three of the necessary conditions of SDF: a fallacy need not be an argument, thus the invalidity condition will not apply either, and the appearance condition is excluded because of its subjective character (Van Eemeren and Grootendorst 2004, 175).

The Pragma-dialectical analysis of fallacies as rule-breakings in a procedure for overcoming disagreements has recently been expanded to take account of the rhetorical dimension of argumentation. Pragma-dialectics takes the rhetorical dimension to stem from an arguer’s wish to have their view accepted which leads dialoguers to engage in strategic maneuvering vis-à-vis their dialogue partners. However, this desire must be put in balance with the dialectical requirement of being reasonable; that is, staying within the bounds of the normative demands of critical discussions. The ways of strategic maneuvering identified are basically three: topic selection, audience orientation, and the selection of presentational devices, and these can be effectively deployed at each stage of argumentation (Van Eemeren 2010, 94). “All derailments of strategic maneuvering are fallacies,” writes van Eemeren (2010, 198), “in the sense that they violate one or more of the rules for critical discussion and all fallacies can be viewed as derailments of strategic maneuvering.” This means that all fallacies are ultimately attributable to the rhetorical dimension of argumentation since, in this model, strategic maneuvering is the entry of rhetoric into argumentation discussions. “Because each fallacy has, in principle, sound counterparts that are manifestations of the same mode of strategic maneuvering” it may not appear to be a fallacy and it “may pass unnoticed” (Van Eemeren 2010, 199). Nevertheless, Pragma-dialectics prefers to keep the appearance condition outside the definition of ‘fallacy’, treating the seeming goodness of fallacies as a sometime co-incidental property, rather than an essential one.

Argumentation evaluation on the Pragma-dialectical approach is done with an eye to a single ideal model of argumentation. This approach has been challenged by Douglas Walton who has written more about fallacies and fallacy theory than anyone else. He has published individual monographs on many of the well-known fallacies, among them, Begging the Question (1991), Slippery Slope Arguments (1992), Ad Hominem Arguments (1998), and a comprehensive work on fallacy theory, A Pragmatic Theory of Fallacy (1995). Over the years his views have evolved. He has referred to his theory as “the Pragmatic theory,” and like the Pragma-dialectical theory it has a dialectical/dialogical basis; however, Walton envisions a number of distinct normative dialectical frameworks (persuasion dialogue, inquiry dialogue, negotiation dialogue, etc.) rather than the single model of a critical discussion proposed by Pragma-dialectics. Postulating different kinds of dialogues with different starting points and different goals, thinks Walton, will bring argumentation into closer contact with argumentation reality. At one point Walton had the idea that fallacies happened when there was an illicit shift from one kind of a dialogue to another (1995, 118–23), for example, using arguments appropriate for a negotiation dialogue in a persuasion dialogue, but more recently he has turned to other ways of explicating fallacies.

Although Walton recognizes the class of formal fallacies, his main interest is in informal fallacies, especially the ones associated with argumentation schemes. The idea of an argumentation scheme is central to Walton’s theory. Schemes are patterns of commonly used kinds of defeasible reasoning/argumentation such as appeals to expert opinion and ad hominem arguments. Schemes do not identify fallacies but rather argument kinds that are sometimes used fairly, and, other times, fallaciously. With each kind of scheme is associated a set of critical questions which guide us in deciding whether a given use of an argument is correct, weak or fallacious. So, if we consider:

\(E\) is an expert in subject area \(S\); \(E\) asserts \(p\) based on \(E\)’s knowledge of \(S\); So, \(p\).

to be the scheme for the appeal-to-expertise kind of argument, [ 8 ] then there will be a question for each premise: Is \(E\) really an expert in \(S\)? Did \(E\) say \(p\) when s/he was acting in her/his professional capacity? (… or did s/he blurt it out while drunk at an association party?). If the answer to both questions is Yes, then the argument creates a presumption for the conclusion—but not a guarantee, for the reasoning is defeasible: other information may come to light that will override the presumption. If one of the questions cannot be answered clearly this is an indication that the argument is weak, and answering No to either of the two questions cancels the presumption for the conclusion, i.e., makes the argument into a bad argument from expert opinion. If the bad argument has “a semblance of correctness about it in [the] context, and poses a serious obstacle to the realization of the goal of the dialog,” then it is a fallacy (2011, 380). [ 9 ]

The definition of fallacy Walton proposes (1995, 255) has five parts. A fallacy:

• an argument (or at least something that purports to be an argument) that
• falls short of some standard of correctness;
• is used in a context of dialogue;
• has a semblance of correctness about it; and
• poses a serious problem to the realization of the goal of the dialogue.

Here we find that Walton has relaxed two of the necessary conditions of SDF. Purporting to be an argument is enough (it doesn’t really have to be an argument), while falling short of a standard (one that will vary with the kind of dialogue under consideration) replaces the invalidity condition. However, the appearance condition, here expressed as fallacies having a semblance of correctness about them, remains in full force. The two extra conditions added to fallacy are that they occur only in contexts of dialogue and that they frustrate the realization of the goal of the kind of dialogue in which they occur. In insisting on this dialogical dimension, Walton is in full sympathy with those who think that fallacies can only be rightly analysed within a dialectical framework similar to the ones Aristotle originally studied, and later better defined by Hamblin and Lorenzen. Walton volunteers a shorter version of the definition of a fallacy as “a deceptively bad argument that impedes the progress of a dialogue” (1995, 256).

Walton divides fallacies into two kinds: paralogisms and sophisms. A paralogism is “the type of fallacy in which an error of reasoning is typically committed by failing to meet some necessary requirement of an argumentation scheme” whereas “the sophism type of fallacy is a sophistical tactic used to try to unfairly get the best of a speech partner in an exchange of arguments” (2010, 171; see also 1995, 254). Paralogisms are instances of identifiable argumentation schemes, but sophisms are not. The latter are associated more with infringing a reasonable expectation of dialogue than with failing some standard of argument, (2011, 385; 2010, 175). A further distinction is drawn between arguments used intentionally to deceive and arguments that merely break a maxim of argumentation unintentionally. The former count as fallacies; the latter, less condemnable, are blunders (1995, 235).

Among the informal paralogisms Walton includes: ad hominem , ad populum , ad misericordiam , ad ignorantiam , ad verecundiam , slippery slope, false cause, straw man, argument from consequences, faulty analogy, composition and division. In the category of sophisms he places ad baculum , complex question, begging the question, hasty generalization, ignoratio elenchi , equivocation, amphiboly, accent, and secundum quid . He also has a class of formal fallacies very much the same as those identified by Whately and Copi. The largest class in Walton’s classification is the one associated with argumentation schemes and ad -arguments, and these are the ones that he considers to be the most central fallacies. Nearly all the Aristotelian fallacies included find themselves relegated to the less studied categories of sophisms. Taking a long look at the history of fallacies, then, we find that the Aristotelian fallacies are no longer of central importance. They have been replaced by the fallacies associated with the ad -arguments.

Another recent approach comes from virtue argumentation theory (modelled on virtue epistemology). Virtue argumentation theory is characterized by a distinct set of virtues thought to be essential to good argumentation: willingness to engage in argumentation, willingness to listen to others and willingness to modify one’s own position (see, e.g., Cohen 2009). These may be supplemented with epistemic virtues and even in some cases moral virtues. Although virtues and vices are dispositions of arguers and fallacies are arguments, it is claimed that good argumentation generally results from the influence of argumentation virtues and bad argumentation (including the fallacies) arise because of the vices of arguers.

Taking the Aristotelian view that virtues are a mean between opposite kinds of vices, fallacious arguments can be seen as resulting from arguers moving in one or another direction away from a mean of good argumentation. Aberdein (2013, 2016) especially has developed this model for understanding many of the fallacies. We can illustrate the view by considering appeals to expertise: the associated vices might be too little respect for reliable authorities at one extreme and too much deference to authorities at the other extreme. Aberdein develops the fallacies-as-argumentation-vices analysis in some detail for other of the ad-arguments and sketches how it might be applied to the other core fallacies, suggesting it can profitably be extended to all of them.

All the fallacies, it is claimed, can be fitted in somewhere in the classification of argumentational vices, but the converse is not true although it is possible to bring to light other shortcomings to which we may fall prey in argumentation. Another aspect of the theory is that it distributes argumentation vices among both senders and audiences. Speakers may infect their arguments with vices when they are, for example, closed minded or lack respect for persons, and audiences can contribute to fallaciousness by letting their receptivity be influenced by naïvety, an over-reliance on common sense, or an unfounded bias against a speaker. Perhaps the development of the virtue argumentation theory approach to fallacies provides a supplement to Mill’s theory of fallacies. He distinguished (1891, V, i, 3) what he called the moral (dispositional) and intellectual causes of fallacy. The study of the argumentative vices envisioned above seems best included under the moral study of fallacies as the vices can be taken to be the presdisposing causes to commit intellectual mistakes, i.e., misevaluations of the weight of evidence.

4. Current issues in fallacy theory

A question that continues to dog fallacy theory is how we are to conceive of fallacies. There would be advantages to having a unified theory of fallacies. It would give us a systematic way of demarcating fallacies and other kinds of mistakes; it would give us a framework for justifying fallacy judgments, and it would give us a sense of the place of fallacies in our larger conceptual schemes. Some general definition of ‘fallacy’ is wanted but the desire is frustrated because there is disagreement about the identity of fallacies. Are they inferential, logical, epistemic or dialectical mistakes? Some authors insist that they are all of one kind: Biro and Siegel, for example, that they are epistemic, and Pragma-dialectics that they are dialectical. There are reasons to think that all fallacies do not easily fit into one category.

Together the Sophistical Refutations and Locke’s Essay are the dual sources of our inheritance of fallacies. However, for four reasons they make for uneasy bedfellows. First, the ad fallacies seem to have a built-in dialectical character, which, it can be argued, Aristotle’s fallacies do not have (they are not sophistical refutations but are in sophistical refutations). Second, Aristotle’s fallacies are logical mistakes: they have no appropriate employment outside eristic argumentation whereas the ad -fallacies are instances of ad -arguments, often appropriately used in dialogues. Third, the appearance condition is part of the Aristotelian inheritance but it is not intimately connected with the ad -fallacies tradition. A fourth reason that contributes to the tension between the Aristotelian and Lockean traditions in fallacies is that the former grew out of philosophical problems, largely what are logical and metaphysical puzzles (consider the many examples in Sophistical Refutations ), whereas the ad -fallacies are more geared to social and political topics of popular concern, the subject matter that most intrigues modern researchers on fallacy theory.

As we look back over our survey we cannot help but observe that fallacies have been identified in relation to some ideal or model of good arguments, good argumentation, or rationality. Aristotle’s fallacies are shortcomings of his ideal of deduction and proof, extended to contexts of refutation. The fallacies listed by Mill are errors of reasoning in a comprehensive model that includes both deduction and induction. Those who have defended SDF as the correct definition of ‘fallacy’ [ 10 ] take logic simpliciter or deductive validity as the ideal of rationality. Informal logicians view fallacies as failures to satisfy the criteria of what they consider to be a cogent argument. Defenders of the epistemic approach to fallacies see them as shortfalls of the standards of knowledge-generating arguments. Finally, those who are concerned with how we are to overcome our disagreements in a reasonable way will see fallacies as failures in relation to ideals of debate or critical discussions.

The standard treatment of the core fallacies has not emerged from a single conception of good argument or reasonableness but rather, like much of our unsystematic knowledge, has grown as a hodgepodge collection of items, proposed at various time and from different perspectives, that continues to draw our attention, even as the standards that originally brought a given fallacy to light are abandoned or absorbed into newer models of rationality. Hence, there is no single conception of good argument or argumentation to be discovered behind the core fallacies, and any attempt to force them all into a single framework, must take efforts to avoid distorting the character originally attributed to each of them.

From Aristotle to Mill the appearance condition was an essential part of the conception of fallacies. However, some of the new, post-Hamblin, scholars have either ignored it (Finocchiaro, Biro and Siegel) or rejected it because appearances can vary from person to person, thus making the same argument a fallacy for the one who is taken in by the appearance, and not a fallacy for the one who sees past the appearances. This is unsatisfactory for those who think that arguments are either fallacies or not. Appearances, it is also argued, have no place in logical or scientific theories because they belong to psychology (van Eemeren and Grootendorst, 2004). But Walton (e.g., 2010) continues to consider appearances an essential part of fallacies as does Powers (1995, 300) who insists that fallacies must “have an appearance, however quickly seen through, of being valid.” If the mistake in an argument is not masked by an ambiguity that makes it appear to be a better argument than it really is, Powers denies it is a fallacy.

The appearance condition of fallacies serves at least two purposes. First, it can be part of explanations of why reasonable people make mistakes in arguments or argumentation: it may be due in part to an argument’s appearing to be better than it really is. Second, it serves to divide mistakes into two groups: those which are trivial or the result of carelessness (for which there is no cure other than paying better attention), and those which we need to learn to detect through an increased awareness of their seductive nature. Without the appearance condition, it can be argued, no division can be made between these two kinds of errors: either there are no fallacies or all mistakes in argument and/or argumentation are fallacies; a conclusion that some are willing to accept, but which runs contrary to tradition. One can also respond that there is an alternative to using the appearance condition as the demarcation property between fallacies and casual mistakes, namely, frequency. Fallacies are those mistakes we must learn to guard against because they occur with noticeable frequency. To this it may be answered that ‘noticeable frequency’ is vague, and is perhaps best explained by the appearance condition.

On the more practical level, there continues to be discussion about the value of teaching the fallacies to students. Is it an effective way for them to learn to reason well and to avoid bad arguments? One reason to think that it is not effective is that the list of fallacies is not complete, and that even if the group of core fallacies was extended to incorporate other fallacies we thought worth including, we could still not be sure that we had a complete prophylactic against bad arguments. Hence, we are better off teaching the positive criteria for good arguments/ argumentation which give us a fuller set of guidelines for good reasoning. But some (Pragma-dialectics and Johnson and Blair) do think that their stock of fallacies is a complete guard against errors because they have specified a full set of necessary conditions for good arguments/argumentation and they hold that fallacies are just failures to meet one of these conditions.

Another consideration about the value of the fallacies approach to teaching good reasoning is that it tends to make students overly critical and lead them to see fallacies where there are not any; hence, it is maintained we could better advance the instilling of critical thinking skills by teaching the positive criteria of good reasoning and arguments (Hitchcock, 1995). In response to this view, it is argued that, if the fallacies are taught in a non-perfunctory way which includes the explanations of why they are fallacies—which normative standards they transgress—then a course taught around the core fallacies can be effective in instilling good reasoning skills (Blair 1995).

Recently there has been renewed interest in how biases are related to fallacies. Correia (2011) has taken Mill’s insight that biases are predisposing causes of fallacies a step further by connecting identifiable biases with particular fallacies. Biases can influence the unintentional committing of fallacies even where there is no intent to be deceptive, he observes. Taking biases to be “systematic errors that invariably distort the subject’s reasoning and judgment,” the picture drawn is that particular biases are activated by desires and emotions (motivated reasoning) and once they are in play, they negatively affect the fair evaluation of evidence. Thus, for example, the “focussing illusion” bias inclines a person to focus on just a part of the evidence available, ignoring or denying evidence that might lead in another direction. Correia (2011, 118) links this bias to the fallacies of hasty generalization and straw man, suggesting that it is our desire to be right that activates the bias to focus more on positive or negative evidence, as the case may be. Other biases he links to other fallacies.

Thagard (2011) is more concerned to stress the differences between fallacies and biases than to find connections between them. He claims that the model of reasoning articulated by informal logic is not a good fit with the way that people actually reason and that only a few of the fallacies are relevant to the kinds of mistakes people actually make. Thagard’s argument depends on his distinction between argument and inference. Arguments, and fallacies, he takes to be serial and linguistic, but inferences are brain activities and are characterized as parallel and multi-modal. By “parallel” is meant that the brain carries out different processes simultaneously, and by “multi-modal” that the brain uses non-linguistic and emotional, as well as linguistic representations in inferring. Biases (inferential error tendencies) can unconsciously affect inferring. “Motivated inference,” for example, “involves selective recruitment and assessment of evidence based on unconscious processes that are driven by emotional considerations of goals rather than purely cognitive reasoning” (2011, 156). Thagard volunteers a list of more than fifty of these inferential error tendencies. Because motivated inferences result from unconscious mental processes rather than explicit reasoning, the errors in inferences cannot be exposed simply by identifying a fallacy in a reconstructed argument. Dealing with biases requires identification of both conscious and unconscious goals of arguers, goals that can figure in explanations of why they incline to particular biases. “Overcoming people’s motivated inferences,” Thagard concludes, “is therefore more akin to psychotherapy than informal logic” (157), and the importance of fallacies is accordingly marginalized.

In response to these findings, one can admit their relevance to the pedagogy of critical thinking but still recall the distinction between what causes mistakes and what the mistakes are. The analysis of fallacies belongs to the normative study of arguments and argumentation, and to give an account of what the fallacy in a given argument is will involve making reference to some norm of argumentation. It will be an explanation of what the mistake in the argument is. Biases are relevant to understanding why people commit fallacies, and how we are to help them get past them, but they do not help us understand what the fallacy-mistakes are in the first place—this is not a question of psychology. Continued research at this intersection of interests will hopefully shed more light on both biases and fallacies.

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• Mill, J. S., 1891, A System of Logic, Ratiocinative and Inductive , 8 th edition, New York: Harper and Brothers; first edition 1843.
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• Pinto, R. C., 1995, Post hoc, ergo propter hoc , in Hansen and Pinto, pp. 302–11.
• Powers, L., 1995, “Equivocation,” in Hansen and Pinto 1995, pp. 287–301.
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How to cite this entry . Preview the PDF version of this entry at the Friends of the SEP Society . Look up topics and thinkers related to this entry at the Internet Philosophy Ontology Project (InPhO). Enhanced bibliography for this entry at PhilPapers , with links to its database.

• Curtis, Gary N., Fallacy Files
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• RAIL , a blog about Reasoning, Argumentation, and Informal Logic.

logic: informal | relativism

Acknowledgments

The author would like to thank the executive and subject editors who suggested a way to improve the discussion of begging the question .

Copyright © 2020 by Hans Hansen < hhansen @ uwindsor . ca >

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What this handout is about

This handout discusses common logical fallacies that you may encounter in your own writing or the writing of others. The handout provides definitions, examples, and tips on avoiding these fallacies.

Most academic writing tasks require you to make an argument—that is, to present reasons for a particular claim or interpretation you are putting forward. You may have been told that you need to make your arguments more logical or stronger. And you may have worried that you simply aren’t a logical person or wondered what it means for an argument to be strong. Learning to make the best arguments you can is an ongoing process, but it isn’t impossible: “Being logical” is something anyone can do, with practice.

Each argument you make is composed of premises (this is a term for statements that express your reasons or evidence) that are arranged in the right way to support your conclusion (the main claim or interpretation you are offering). You can make your arguments stronger by:

• using good premises (ones you have good reason to believe are both true and relevant to the issue at hand),
• making sure your premises provide good support for your conclusion (and not some other conclusion, or no conclusion at all),
• checking that you have addressed the most important or relevant aspects of the issue (that is, that your premises and conclusion focus on what is really important to the issue), and
• not making claims that are so strong or sweeping that you can’t really support them.

You also need to be sure that you present all of your ideas in an orderly fashion that readers can follow. See our handouts on argument and organization for some tips that will improve your arguments.

This handout describes some ways in which arguments often fail to do the things listed above; these failings are called fallacies. If you’re having trouble developing your argument, check to see if a fallacy is part of the problem.

It is particularly easy to slip up and commit a fallacy when you have strong feelings about your topic—if a conclusion seems obvious to you, you’re more likely to just assume that it is true and to be careless with your evidence. To help you see how people commonly make this mistake, this handout uses a number of controversial political examples—arguments about subjects like abortion, gun control, the death penalty, gay marriage, euthanasia, and pornography. The purpose of this handout, though, is not to argue for any particular position on any of these issues; rather, it is to illustrate weak reasoning, which can happen in pretty much any kind of argument. Please be aware that the claims in these examples are just made-up illustrations—they haven’t been researched, and you shouldn’t use them as evidence in your own writing.

What are fallacies?

Fallacies are defects that weaken arguments. By learning to look for them in your own and others’ writing, you can strengthen your ability to evaluate the arguments you make, read, and hear. It is important to realize two things about fallacies: first, fallacious arguments are very, very common and can be quite persuasive, at least to the casual reader or listener. You can find dozens of examples of fallacious reasoning in newspapers, advertisements, and other sources. Second, it is sometimes hard to evaluate whether an argument is fallacious. An argument might be very weak, somewhat weak, somewhat strong, or very strong. An argument that has several stages or parts might have some strong sections and some weak ones. The goal of this handout, then, is not to teach you how to label arguments as fallacious or fallacy-free, but to help you look critically at your own arguments and move them away from the “weak” and toward the “strong” end of the continuum.

So what do fallacies look like?

For each fallacy listed, there is a definition or explanation, an example, and a tip on how to avoid committing the fallacy in your own arguments.

Hasty generalization

Definition: Making assumptions about a whole group or range of cases based on a sample that is inadequate (usually because it is atypical or too small). Stereotypes about people (“librarians are shy and smart,” “wealthy people are snobs,” etc.) are a common example of the principle underlying hasty generalization.

Example: “My roommate said her philosophy class was hard, and the one I’m in is hard, too. All philosophy classes must be hard!” Two people’s experiences are, in this case, not enough on which to base a conclusion.

Tip: Ask yourself what kind of “sample” you’re using: Are you relying on the opinions or experiences of just a few people, or your own experience in just a few situations? If so, consider whether you need more evidence, or perhaps a less sweeping conclusion. (Notice that in the example, the more modest conclusion “Some philosophy classes are hard for some students” would not be a hasty generalization.)

Missing the point

Definition: The premises of an argument do support a particular conclusion—but not the conclusion that the arguer actually draws.

Example: “The seriousness of a punishment should match the seriousness of the crime. Right now, the punishment for drunk driving may simply be a fine. But drunk driving is a very serious crime that can kill innocent people. So the death penalty should be the punishment for drunk driving.” The argument actually supports several conclusions—”The punishment for drunk driving should be very serious,” in particular—but it doesn’t support the claim that the death penalty, specifically, is warranted.

Tip: Separate your premises from your conclusion. Looking at the premises, ask yourself what conclusion an objective person would reach after reading them. Looking at your conclusion, ask yourself what kind of evidence would be required to support such a conclusion, and then see if you’ve actually given that evidence. Missing the point often occurs when a sweeping or extreme conclusion is being drawn, so be especially careful if you know you’re claiming something big.

Post hoc (also called false cause)

This fallacy gets its name from the Latin phrase “post hoc, ergo propter hoc,” which translates as “after this, therefore because of this.”

Definition: Assuming that because B comes after A, A caused B. Of course, sometimes one event really does cause another one that comes later—for example, if I register for a class, and my name later appears on the roll, it’s true that the first event caused the one that came later. But sometimes two events that seem related in time aren’t really related as cause and event. That is, correlation isn’t the same thing as causation.

Examples: “President Jones raised taxes, and then the rate of violent crime went up. Jones is responsible for the rise in crime.” The increase in taxes might or might not be one factor in the rising crime rates, but the argument hasn’t shown us that one caused the other.

Tip: To avoid the post hoc fallacy, the arguer would need to give us some explanation of the process by which the tax increase is supposed to have produced higher crime rates. And that’s what you should do to avoid committing this fallacy: If you say that A causes B, you should have something more to say about how A caused B than just that A came first and B came later.

Slippery slope

Definition: The arguer claims that a sort of chain reaction, usually ending in some dire consequence, will take place, but there’s really not enough evidence for that assumption. The arguer asserts that if we take even one step onto the “slippery slope,” we will end up sliding all the way to the bottom; they assume we can’t stop partway down the hill.

Example: “Animal experimentation reduces our respect for life. If we don’t respect life, we are likely to be more and more tolerant of violent acts like war and murder. Soon our society will become a battlefield in which everyone constantly fears for their lives. It will be the end of civilization. To prevent this terrible consequence, we should make animal experimentation illegal right now.” Since animal experimentation has been legal for some time and civilization has not yet ended, it seems particularly clear that this chain of events won’t necessarily take place. Even if we believe that experimenting on animals reduces respect for life, and loss of respect for life makes us more tolerant of violence, that may be the spot on the hillside at which things stop—we may not slide all the way down to the end of civilization. And so we have not yet been given sufficient reason to accept the arguer’s conclusion that we must make animal experimentation illegal right now.

Like post hoc, slippery slope can be a tricky fallacy to identify, since sometimes a chain of events really can be predicted to follow from a certain action. Here’s an example that doesn’t seem fallacious: “If I fail English 101, I won’t be able to graduate. If I don’t graduate, I probably won’t be able to get a good job, and I may very well end up doing temp work or flipping burgers for the next year.”

Tip: Check your argument for chains of consequences, where you say “if A, then B, and if B, then C,” and so forth. Make sure these chains are reasonable.

Weak analogy

Definition: Many arguments rely on an analogy between two or more objects, ideas, or situations. If the two things that are being compared aren’t really alike in the relevant respects, the analogy is a weak one, and the argument that relies on it commits the fallacy of weak analogy.

Example: “Guns are like hammers—they’re both tools with metal parts that could be used to kill someone. And yet it would be ridiculous to restrict the purchase of hammers—so restrictions on purchasing guns are equally ridiculous.” While guns and hammers do share certain features, these features (having metal parts, being tools, and being potentially useful for violence) are not the ones at stake in deciding whether to restrict guns. Rather, we restrict guns because they can easily be used to kill large numbers of people at a distance. This is a feature hammers do not share—it would be hard to kill a crowd with a hammer. Thus, the analogy is weak, and so is the argument based on it.

If you think about it, you can make an analogy of some kind between almost any two things in the world: “My paper is like a mud puddle because they both get bigger when it rains (I work more when I’m stuck inside) and they’re both kind of murky.” So the mere fact that you can draw an analogy between two things doesn’t prove much, by itself.

Arguments by analogy are often used in discussing abortion—arguers frequently compare fetuses with adult human beings, and then argue that treatment that would violate the rights of an adult human being also violates the rights of fetuses. Whether these arguments are good or not depends on the strength of the analogy: do adult humans and fetuses share the properties that give adult humans rights? If the property that matters is having a human genetic code or the potential for a life full of human experiences, adult humans and fetuses do share that property, so the argument and the analogy are strong; if the property is being self-aware, rational, or able to survive on one’s own, adult humans and fetuses don’t share it, and the analogy is weak.

Tip: Identify what properties are important to the claim you’re making, and see whether the two things you’re comparing both share those properties.

Appeal to authority

Definition: Often we add strength to our arguments by referring to respected sources or authorities and explaining their positions on the issues we’re discussing. If, however, we try to get readers to agree with us simply by impressing them with a famous name or by appealing to a supposed authority who really isn’t much of an expert, we commit the fallacy of appeal to authority.

Example: “We should abolish the death penalty. Many respected people, such as actor Guy Handsome, have publicly stated their opposition to it.” While Guy Handsome may be an authority on matters having to do with acting, there’s no particular reason why anyone should be moved by his political opinions—he is probably no more of an authority on the death penalty than the person writing the paper.

Tip: There are two easy ways to avoid committing appeal to authority: First, make sure that the authorities you cite are experts on the subject you’re discussing. Second, rather than just saying “Dr. Authority believes X, so we should believe it, too,” try to explain the reasoning or evidence that the authority used to arrive at their opinion. That way, your readers have more to go on than a person’s reputation. It also helps to choose authorities who are perceived as fairly neutral or reasonable, rather than people who will be perceived as biased.

Definition: The Latin name of this fallacy means “to the people.” There are several versions of the ad populum fallacy, but in all of them, the arguer takes advantage of the desire most people have to be liked and to fit in with others and uses that desire to try to get the audience to accept their argument. One of the most common versions is the bandwagon fallacy, in which the arguer tries to convince the audience to do or believe something because everyone else (supposedly) does.

Example: “Gay marriages are just immoral. 70% of Americans think so!” While the opinion of most Americans might be relevant in determining what laws we should have, it certainly doesn’t determine what is moral or immoral: there was a time where a substantial number of Americans were in favor of segregation, but their opinion was not evidence that segregation was moral. The arguer is trying to get us to agree with the conclusion by appealing to our desire to fit in with other Americans.

Tip: Make sure that you aren’t recommending that your readers believe your conclusion because everyone else believes it, all the cool people believe it, people will like you better if you believe it, and so forth. Keep in mind that the popular opinion is not always the right one.

Ad hominem and tu quoque

Definitions: Like the appeal to authority and ad populum fallacies, the ad hominem (“against the person”) and tu quoque (“you, too!”) fallacies focus our attention on people rather than on arguments or evidence. In both of these arguments, the conclusion is usually “You shouldn’t believe So-and-So’s argument.” The reason for not believing So-and-So is that So-and-So is either a bad person (ad hominem) or a hypocrite (tu quoque). In an ad hominem argument, the arguer attacks their opponent instead of the opponent’s argument.

Examples: “Andrea Dworkin has written several books arguing that pornography harms women. But Dworkin is just ugly and bitter, so why should we listen to her?” Dworkin’s appearance and character, which the arguer has characterized so ungenerously, have nothing to do with the strength of her argument, so using them as evidence is fallacious.

In a tu quoque argument, the arguer points out that the opponent has actually done the thing they are arguing against, and so the opponent’s argument shouldn’t be listened to. Here’s an example: imagine that your parents have explained to you why you shouldn’t smoke, and they’ve given a lot of good reasons—the damage to your health, the cost, and so forth. You reply, “I won’t accept your argument, because you used to smoke when you were my age. You did it, too!” The fact that your parents have done the thing they are condemning has no bearing on the premises they put forward in their argument (smoking harms your health and is very expensive), so your response is fallacious.

Tip: Be sure to stay focused on your opponents’ reasoning, rather than on their personal character. (The exception to this is, of course, if you are making an argument about someone’s character—if your conclusion is “President Jones is an untrustworthy person,” premises about her untrustworthy acts are relevant, not fallacious.)

Appeal to pity

Definition: The appeal to pity takes place when an arguer tries to get people to accept a conclusion by making them feel sorry for someone.

Examples: “I know the exam is graded based on performance, but you should give me an A. My cat has been sick, my car broke down, and I’ve had a cold, so it was really hard for me to study!” The conclusion here is “You should give me an A.” But the criteria for getting an A have to do with learning and applying the material from the course; the principle the arguer wants us to accept (people who have a hard week deserve A’s) is clearly unacceptable. The information the arguer has given might feel relevant and might even get the audience to consider the conclusion—but the information isn’t logically relevant, and so the argument is fallacious. Here’s another example: “It’s wrong to tax corporations—think of all the money they give to charity, and of the costs they already pay to run their businesses!”

Tip: Make sure that you aren’t simply trying to get your audience to agree with you by making them feel sorry for someone.

Appeal to ignorance

Definition: In the appeal to ignorance, the arguer basically says, “Look, there’s no conclusive evidence on the issue at hand. Therefore, you should accept my conclusion on this issue.”

Example: “People have been trying for centuries to prove that God exists. But no one has yet been able to prove it. Therefore, God does not exist.” Here’s an opposing argument that commits the same fallacy: “People have been trying for years to prove that God does not exist. But no one has yet been able to prove it. Therefore, God exists.” In each case, the arguer tries to use the lack of evidence as support for a positive claim about the truth of a conclusion. There is one situation in which doing this is not fallacious: if qualified researchers have used well-thought-out methods to search for something for a long time, they haven’t found it, and it’s the kind of thing people ought to be able to find, then the fact that they haven’t found it constitutes some evidence that it doesn’t exist.

Tip: Look closely at arguments where you point out a lack of evidence and then draw a conclusion from that lack of evidence.

Definition: One way of making our own arguments stronger is to anticipate and respond in advance to the arguments that an opponent might make. In the straw man fallacy, the arguer sets up a weak version of the opponent’s position and tries to score points by knocking it down. But just as being able to knock down a straw man (like a scarecrow) isn’t very impressive, defeating a watered-down version of your opponent’s argument isn’t very impressive either.

Example: “Feminists want to ban all pornography and punish everyone who looks at it! But such harsh measures are surely inappropriate, so the feminists are wrong: porn and its fans should be left in peace.” The feminist argument is made weak by being overstated. In fact, most feminists do not propose an outright “ban” on porn or any punishment for those who merely view it or approve of it; often, they propose some restrictions on particular things like child porn, or propose to allow people who are hurt by porn to sue publishers and producers—not viewers—for damages. So the arguer hasn’t really scored any points; they have just committed a fallacy.

Tip: Be charitable to your opponents. State their arguments as strongly, accurately, and sympathetically as possible. If you can knock down even the best version of an opponent’s argument, then you’ve really accomplished something.

Red herring

Definition: Partway through an argument, the arguer goes off on a tangent, raising a side issue that distracts the audience from what’s really at stake. Often, the arguer never returns to the original issue.

Example: “Grading this exam on a curve would be the most fair thing to do. After all, classes go more smoothly when the students and the professor are getting along well.” Let’s try our premise-conclusion outlining to see what’s wrong with this argument:

Premise: Classes go more smoothly when the students and the professor are getting along well.

Conclusion: Grading this exam on a curve would be the most fair thing to do.

When we lay it out this way, it’s pretty obvious that the arguer went off on a tangent—the fact that something helps people get along doesn’t necessarily make it more fair; fairness and justice sometimes require us to do things that cause conflict. But the audience may feel like the issue of teachers and students agreeing is important and be distracted from the fact that the arguer has not given any evidence as to why a curve would be fair.

Tip: Try laying your premises and conclusion out in an outline-like form. How many issues do you see being raised in your argument? Can you explain how each premise supports the conclusion?

False dichotomy

Definition: In false dichotomy, the arguer sets up the situation so it looks like there are only two choices. The arguer then eliminates one of the choices, so it seems that we are left with only one option: the one the arguer wanted us to pick in the first place. But often there are really many different options, not just two—and if we thought about them all, we might not be so quick to pick the one the arguer recommends.

Example: “Caldwell Hall is in bad shape. Either we tear it down and put up a new building, or we continue to risk students’ safety. Obviously we shouldn’t risk anyone’s safety, so we must tear the building down.” The argument neglects to mention the possibility that we might repair the building or find some way to protect students from the risks in question—for example, if only a few rooms are in bad shape, perhaps we shouldn’t hold classes in those rooms.

Tip: Examine your own arguments: if you’re saying that we have to choose between just two options, is that really so? Or are there other alternatives you haven’t mentioned? If there are other alternatives, don’t just ignore them—explain why they, too, should be ruled out. Although there’s no formal name for it, assuming that there are only three options, four options, etc. when really there are more is similar to false dichotomy and should also be avoided.

Begging the question

Definition: A complicated fallacy; it comes in several forms and can be harder to detect than many of the other fallacies we’ve discussed. Basically, an argument that begs the question asks the reader to simply accept the conclusion without providing real evidence; the argument either relies on a premise that says the same thing as the conclusion (which you might hear referred to as “being circular” or “circular reasoning”), or simply ignores an important (but questionable) assumption that the argument rests on. Sometimes people use the phrase “beg the question” as a sort of general criticism of arguments, to mean that an arguer hasn’t given very good reasons for a conclusion, but that’s not the meaning we’re going to discuss here.

Examples: “Active euthanasia is morally acceptable. It is a decent, ethical thing to help another human being escape suffering through death.” Let’s lay this out in premise-conclusion form:

Premise: It is a decent, ethical thing to help another human being escape suffering through death.

Conclusion: Active euthanasia is morally acceptable.

If we “translate” the premise, we’ll see that the arguer has really just said the same thing twice: “decent, ethical” means pretty much the same thing as “morally acceptable,” and “help another human being escape suffering through death” means something pretty similar to “active euthanasia.” So the premise basically says, “active euthanasia is morally acceptable,” just like the conclusion does. The arguer hasn’t yet given us any real reasons why euthanasia is acceptable; instead, they have left us asking “well, really, why do you think active euthanasia is acceptable?” Their argument “begs” (that is, evades) the real question.

Here’s a second example of begging the question, in which a dubious premise which is needed to make the argument valid is completely ignored: “Murder is morally wrong. So active euthanasia is morally wrong.” The premise that gets left out is “active euthanasia is murder.” And that is a debatable premise—again, the argument “begs” or evades the question of whether active euthanasia is murder by simply not stating the premise. The arguer is hoping we’ll just focus on the uncontroversial premise, “Murder is morally wrong,” and not notice what is being assumed.

Tip: One way to try to avoid begging the question is to write out your premises and conclusion in a short, outline-like form. See if you notice any gaps, any steps that are required to move from one premise to the next or from the premises to the conclusion. Write down the statements that would fill those gaps. If the statements are controversial and you’ve just glossed over them, you might be begging the question. Next, check to see whether any of your premises basically says the same thing as the conclusion (but in different words). If so, you’re probably begging the question. The moral of the story: you can’t just assume or use as uncontroversial evidence the very thing you’re trying to prove.

Equivocation

Definition: Equivocation is sliding between two or more different meanings of a single word or phrase that is important to the argument.

Example: “Giving money to charity is the right thing to do. So charities have a right to our money.” The equivocation here is on the word “right”: “right” can mean both something that is correct or good (as in “I got the right answers on the test”) and something to which someone has a claim (as in “everyone has a right to life”). Sometimes an arguer will deliberately, sneakily equivocate, often on words like “freedom,” “justice,” “rights,” and so forth; other times, the equivocation is a mistake or misunderstanding. Either way, it’s important that you use the main terms of your argument consistently.

Tip: Identify the most important words and phrases in your argument and ask yourself whether they could have more than one meaning. If they could, be sure you aren’t slipping and sliding between those meanings.

So how do I find fallacies in my own writing?

Here are some general tips for finding fallacies in your own arguments:

• Pretend you disagree with the conclusion you’re defending. What parts of the argument would now seem fishy to you? What parts would seem easiest to attack? Give special attention to strengthening those parts.
• List your main points; under each one, list the evidence you have for it. Seeing your claims and evidence laid out this way may make you realize that you have no good evidence for a particular claim, or it may help you look more critically at the evidence you’re using.
• Learn which types of fallacies you’re especially prone to, and be careful to check for them in your work. Some writers make lots of appeals to authority; others are more likely to rely on weak analogies or set up straw men. Read over some of your old papers to see if there’s a particular kind of fallacy you need to watch out for.
• Be aware that broad claims need more proof than narrow ones. Claims that use sweeping words like “all,” “no,” “none,” “every,” “always,” “never,” “no one,” and “everyone” are sometimes appropriate—but they require a lot more proof than less-sweeping claims that use words like “some,” “many,” “few,” “sometimes,” “usually,” and so forth.
• Double check your characterizations of others, especially your opponents, to be sure they are accurate and fair.

Can I get some practice with this?

Yes, you can. Follow this link to see a sample argument that’s full of fallacies (and then you can follow another link to get an explanation of each one). Then there’s a more well-constructed argument on the same topic.

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout’s topic, and we encourage you to do your own research to find additional publications. Please do not use this list as a model for the format of your own reference list, as it may not match the citation style you are using. For guidance on formatting citations, please see the UNC Libraries citation tutorial . We revise these tips periodically and welcome feedback.

Copi, Irving M., Carl Cohen, and Victor Rodych. 1998. Introduction to Logic . London: Pearson Education.

Hurley, Patrick J. 2000. A Concise Introduction to Logic , 7th ed. Belmont, CA: Wadsworth.

Lunsford, Andrea A., and John J. Ruszkiewicz. 2016. Everything’s an Argument , 7th ed. Boston: Bedford/St Martin’s.

You may reproduce it for non-commercial use if you use the entire handout and attribute the source: The Writing Center, University of North Carolina at Chapel Hill

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9 Logical Fallacies That You Need to Know To Master Critical Thinking

When you learn about logic, language becomes a game you can win..

William James, who was known as the grandfather of psychology, once said: “A great many people think they are thinking when they are merely rearranging their prejudices.” All of us think, every day. But there’s a difference between thinking for thinking’s sake, and thinking in a critical way. Deliberate, controlled, and reasonable thinking is rare.

There are multiple factors that are impairing people’s ability to think critically, from technology to changes in education. Some experts have speculated we’re approaching a crisis of critical thinking , with many students graduating “without the ability to construct a cohesive argument or identify a logical fallacy.”

RELATED: How to Tell if ‘Political Correctness’ Is Hurting Your Mental Health

That's a worrying trend, as critical thinking isn’t only an academic skill, but essential to living a high-functioning life. It’s the process by which to arrive at logical conclusions. And in through that process, logical fallacies are a significant hazard.

This article will explore logical fallacies in order to equip you with the knowledge on how to think in skillful ways, for the biggest benefits. As a result, you'll be able to detect deception of flawed logic, in others, and yourself. And you'll be equipped to think proper thoughts, rather than simply rearrange prejudices.

What Is a Logical Fallacy?

The study of logic originates back to the Greek philosopher Aristotle (384–322 b.c.e), who started to systematically identify and list logical fallacies. The origin of logic is linked to the Greek logos , which translates to language, reason, or discourse. Logical fallacies are errors of reason that invalidate an argument. The use of logical fallacies changes depending on a person’s intention. Although for many, they’re unintentional, others may deliberately use logical fallacies as a type of manipulative behavior .

Detecting logical fallacies is crucial to improve your level of critical thinking, to avoid deceit, and to spot poor reasoning; within yourself and others. The influential German philosopher Immanuel Kant once said; “All our knowledge begins with the senses, proceeds then to the understanding, and ends with reason. There is nothing higher than reason.”

RELATED: Fundamental Attribution Error: Definition & Examples

Throughout history, the world’s greatest thinkers have promoted the value of reasoning. Away from academia, reason is the ability to logically process information, and arrive at an accurate conclusion, in the quest for truth. Striving to be more reasonable or calm under pressure is a virtuous act. It’s a noble pursuit, one which in its nature will inspire your personal development, and allow you to become the best version of yourself.

Why Critical Thinking Is Important

It seems like humanity has never been so polarized, separated into different camps and stances; Democrats vs. Liberals, vegans vs. meat eaters, vaccinated vs. unvaccinated, pro-life vs. pro-choice. There’s nothing inherently wrong with thinking critically, and taking a stand. However, what is unusual is the tendency for people to lean into one extreme or the other, neglecting to explore gray areas or complexity.

Many of the positions people take are chosen for them. It takes a lot of effort to research a point of view. And even then, we’re faced with the challenge of information overload, fake news, conspiracy, and even credible news which is dismissed as conspiracy. Far from academic debates or politicians facing off during leadership races, the ability to share respectful dialogue is an essential part of understanding our place in the world, and maintaining human relationships.

The hot topics facing humanity aren’t going to be resolved by reactivity or over-emotionality . There should be room for all sorts of emotions to surface; it’s understandable to feel anger, grief, anxiety, etc, faced with global events. But critical thinking asks for a more reasoned, calm consideration, not getting completely carried away with emotions, but appealing to higher judgment.

Examples of When to Use Critical Thinking

It’s not always clear why critical thinking is so valuable. Isn’t it only useful for education, philosophy, science, or politics? Not quite. When applied appropriately, logic has a universal appeal in life. Examples include:

• Problem-solving : “The problem is not that there are problems,” wrote psychiatrist Theodore Isaac Rubin, “the problem is expecting otherwise, and thinking that having problems is a problem.” Life is full of problems. Fortunately, that means life is full of opportunities to problem solve. Critical thinking is an essential problem-solving skill, from managing your time to organizing your finances.
• Making optimal decisions : the more logical you are, and the less you fall into logical fallacies, the better your decision-making becomes . Decisions are the steps towards your goals, each decision making you closer to, or away from, what you really desire.
• Understanding complex subjects : with attention spans reducing due to social media and technology, it’s becoming rare to take time to attempt to understand complex topics, away from repeating what others have said. Whether through self-study or to comprehend global events, critical thinking is essential to understand complexity.
• Improving relationships : adding a dose of logic to your interactions will allow you to make better choices in relationships. Many “messy” forms of communication, from guilt-tripping to passive aggression, are illogical. By tapping into a more balanced point of view, you’ll better overcome conflict, argue your point (when necessary), or explain the way you feel.

The Most Common Logical Fallacies

When you begin to explore logical fallacies, language becomes a game. There’s a sense of having a cheat sheet in communication, understanding the underlying dynamics at play. Of course, it’s not as straightforward as a mechanical understanding — emotional intelligence, and non-verbal body language has a role to play, too. We’re humans, not computers. But gaining mastery of logic puts you ahead of the majority of people, and helps you avoid cognitive bias.

What’s more, most people fall into logical fallacies without being aware. Once you can detect these mechanisms, within yourself and with others, you’ll have an upper hand in many key areas of life, not least in a professional setting, or in any place you need to persuade or argue a point. The list is ever-growing and vast, but below are the most common logical fallacies to get the ball rolling:

1. Ad Hominem

Originating from a Latin phrase meaning “to the person,” ad hominem is an attack on the person, not the argument. This has a twofold impact — it deflects attention away from the validity of the argument, and second, it can provoke the person to enter a defensive mindset. If you’re aware of this fallacy, it can keep you from taking the bait, and instead keeping the focus on the argument.

Perhaps the most popular example of this in recent times is the viral interview between Jordan Peterson and Cathy Newman. Love him or hate him, Peterson is an embodiment of logic, sidestepping Newman’s ad hominem attacks and fallacies in a calm and controlled manner. 

2. Red Herring

You might have heard of this phrase in the context of fiction: a red herring is an irrelevant piece of information thrown into the mix, in order to distract from other relevant details, commonly used in detective stories. In a political context, you might see a politician respond to criticism by talking about something positive they’ve done. For example, when asked why unemployment is so high, they may say “we’ve made a lot of effort to improve working conditions in certain areas.”

A popular type of red herring in modern discourse is "what aboutism," a form of counter-accusation. If the person mentioning unemployment is a fellow politician, the same politician may say: “what about unemployment rates when your party was in charge?”

3. Tu Quoque Fallacy

Closely related to the above, and in some ways, a mixture of the ad hominem and a red herring, is the tu quoque fallacy (pronounced tu-KWO-kway and originating from the Latin “you too”). This is a counter-accusation that accuses someone of hypocrisy. Rather than acknowledging what's been said, someone responds with a direct allegation. For example, if you’re in an argument and your partner raises their voice, you may bring that to their attention, only for them to say: “you raise your voice all the time!”.

4. Straw Man

The straw man logical fallacy is everywhere, especially in dialogue on hot-topic issues, because it's effective in shutting down someone else’s perspective. The person runs with someone’s point, exaggerates it, then attacks the exaggerated version — the straw man — seemingly in an appropriate way. For example, when your partner asks if you could do the washing up, you might respond: “are you saying I don’t support you around the house? That’s unfair.”

On the global stage, one of the big straw man arguments in recent times is the rhetoric of the anti-vaxxer, applied to resistance to mandated vaccines, social distancing, or lockdowns. The simplified term is a way of positioning someone as extreme, even if raising valid points, or looking to open dialogue about the repercussions of certain political choices, made without the option for the population to have their say.

5. Appeal to Authority

If someone in a position of authority says something is true, it must be true. This type of logical fallacy is ingrained in the psyche in childhood, where your parents' (or adults around you) word was final. Society is moving increasingly in this direction, especially in the fields of science. But that doesn’t come without risk, as even experts are known not to get things right. 

In addition, many positions of authority aren’t always acting in pursuit of honesty or truth, if other factors (such as financial donations) have influence. While appeals to authority used to gravitate around religious leaders, a 2022 study found that, when linked with scientists, untrue statements are more likely to be believed, in what researchers call the Einstein effect .

6. False Dichotomy

Also known as the false dilemma, this logical fallacy presents limited options in certain scenarios in a way that is inaccurate. It’s closely linked to black-or-white thinking or all-or-nothing thinking, presenting two extremes without options in between. This is perhaps one of the most invasive logical fallacies in navigating life’s demands. For example, you either go to the gym or become unhealthy.

These limitations require a dose of psychological flexibility and creative thinking to overcome. They require exploring other alternatives. In the example above, that would mean looking at other ways to become healthy and exercise, such as running outdoors or going swimming.

7. Slippery Slope Fallacy

Similar to the straw man fallacy, the slippery slope is a way of taking an issue to a hypothetical extreme and then dismissing it based on what could happen. The potential of one thing leading to another, and the repercussions of that chain of events, may cause the original issue to be overlooked. For example, if you fail to set a boundary in one situation, you’ll forever be stuck in accepting certain behaviors.

The issue with this fallacy is that a valid process of critical thinking is to look at what decisions can lead to in the future. Rather than dismiss outright, however, it pays to make reasoned decisions, avoid jumping to conclusions, and see how things unfold over time.

8. Sunk Cost Fallacy

This is the logical fallacy that, when having already invested in something, you continue to invest in order to get return on your sunk costs. Although using gambling terminology (such as chasing losses on roulette) the sunk cost can apply to any area of life. The investment itself doesn’t have to be financial. For example, investing lots of time and energy into a creative project, or a relationship.

The sunk cost fallacy causes people to overlook a true and accurate analysis of the situation in the present moment, instead choosing to continue because of past decisions.

9. Hasty Generalisation

Also known as an over-generalization or faulty generalization, this logical fallacy makes general claims based on little evidence. Before writing this article, I went to a new gym, where my toiletry bag was stolen. You could argue it’s bad luck for something like that to happen on your first visit. If I decide that the gym isn’t safe, and make a hasty generalization, I may end up not going again. But what if the rate of theft in this gym was below the average in the city, and I was just unlucky? What if it wasn’t stolen, but someone absent-mindedly put it in their bag?

The opposite of a hasty generalization is to find the appropriate context for events. A logical conclusion, on the other hand, takes time. It’s reasonable, doesn’t jump in, and collects as much data as possible. If I go to the same gym, and something else is stolen, and I then see in Google reviews that others have had the same, it’d be logical for me to conclude there’s a high rate of theft.

How to Detect and Overcome Logical Fallacies

Both logic and critical thinking can be improved with practice. The knowledge of the nature of logical fallacies, and the above examples, will get you started. Deciphering when certain fallacies are active in real time is part of applied learning. Be conscious of applying the same level of rigor to your own level of reason as you do others.

There are a few components to detect and overcome logical fallacies. The first is self-awareness. As mentioned above, we’re humans, not machines. In situations where the stakes are high, we’re usually driven by factors other than logic, ulterior motives, or strong emotions that run the show. How often, when angry or triggered, do you say or act in ways you later regret?

Emotional regulation is useful in being calm enough to engage in critical thinking. But at times, logic isn’t the most skillful. For example, in conflict with a loved one, it’s more important to attempt to have compassion and understanding than to be the “most logical.” Sometimes, there are factors outside of reason that influence us, matters of the heart that can’t be captured, defined, or deconstructed by the mind.

Knowing how to apply logic, and when, is a vital skill. Through practice, over time, you’ll cultivate an even greater virtue — wisdom. A precious commodity in short supply, if you’re able to achieve wisdom and reason, the world is your oyster, a positive slippery slope to supercharge your growth.

KEEP READING

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Police Officer Is Now Family After Saving Three-Month-Old

Being a new parent is terrifying because you’re always expecting the worst. But when the worst actually happens, and your baby stops breathing, you hope that a stranger like this police officer will be there to save the day.

A Harrowing Incident

Officer Mike Harton sits with Tooka, he girl whose life he once saved

CBS News/YouTube

A normal day at the movies turned into a new mother ’s worst nightmare five years ago when her three-month-old daughter Tooka stopped breathing. Nikki Huckaby ran out of the theater and screamed for help.

“I was standing there, and that’s when she came running toward this way,” Officer Mike Harton recalled to CNN . “[The baby] curled back, trying to take a breath, and then she went completely limp on me.”

It was then that Harton’s training kicked in and he started performing chest compressions and back blows, trying to get Tooka breathing again.

“All I was thinking, is like, she cannot die in this movie theater,” Huckaby recalled.

“All I could think in my head was, 'Not on my watch, not on my watch,'” Harton added.

Saving a Life

After 30 long seconds, Tooka finally released a small cry. It was music to the mom and officer’s ears. “That cry was the best cry ever,” Harton said.

“I literally watched a miracle happen before my eyes,” Huckaby said.

From that moment on, Harton began calling Tooka “Little Angel” and the officer became a part of the family ’s life. He was even asked to be Tooka’s godfather. Today, he’s there for all of the five-year-old’s big life events: birthdays, holidays, and the first day of school. Tooka even wants to be a police officer when she grows up.

“That day, an angel came down,” Harton continued. “She did more for me than I did for her. My life changed that day. Our family got extended, and it’s amazing.”

Positive Relationships

In the interview, Huckaby explained that she and Harton wanted to share their story to show that positive police relationships can — and should — exist.

“A lot of people don’t get a chance to have that positive relationship with police officers. I hope this story is an example of how you can come together from different worlds and really be family because we are humans first,” Huckaby said.

It’s a nice reminder that the police in our communities do more than we think and are there to serve first and foremost. By highlighting more of these examples, we can deepen our relationships with police officers who show up for those in need, lend a helping hand, and continue to show up long after their official duties are done.

He Thought He’d Be the First Black Man in Space — Now the 90-Year-Old’s Dream is Coming True

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Interracial Couple Inspires Next Gen 40 Years After Wedding

When Mike and Jeralyn Wirtz wed more than four decades ago in Virginia, interracial marriage had only been legal for 10 years. Fast forward to today, and their love story is inspiring a new generation thanks to the couple’s active participation in social media .

Destined to be Together

See on Instagram

When the Wirtzs met in 1976, they had both already made strong friendships with people of other races. So when they came into each other’s orbits, race was far from their minds. The couple lived in the same apartment complex, and they noticed each other hanging around the pool.

“I thought, ‘I like this girl, and she’s very attractive and I’m interested in her,’ and so we just started dating,” Mike recalled to Today .

“Obviously, I realized it was an interracial type of situation. I didn’t feel overwhelmed by it, though, because I think one thing that helped was eventually when she met my parents, they welcomed her with open arms, and her family was the same way with me.”

The couple fell in love and married in 1977 — almost 10 years after the Supreme Court struck down laws banning interracial marriage . Mike and Jeralyn had two children and went through life together, even when life threw them challenges.

“We knew that prejudice was out there and people would probably be looking at us, but we didn’t look for that,” Jeralyn added to the publication. “We didn’t, you know, engage in it.”

An Inspiring Love Story

two people holding papercut heart

When the pandemic hit, the Wirtzs decided to create a TikTok account to connect with their children and their grandchildren. Eventually, they began posting videos and old photographs of their love story, and people came flocking.

Today, their account boasts more than 370,000 followers and nearly 16 million likes.

“I’m not like Jeri. I don’t embrace it as much,” Mike said of their newfound fame. “We’re doing something that we enjoy, and we’re having fun at it. And I would have never in a million years guessed that other people would be interested in watching these videos.”

“I like it. I love it. I think it’s fun,” added Jeralyn. “I get to tease my younger friends that are working on becoming influencers and don’t have a lot of followers. I’m like, ‘I’m 72 years old and I’m a ‘YouTuber’ or an ‘influencer.’ It’s fun and funny for us.”

Love Conquers All

If you ever needed a love story to remind you of the power of true love, this is it. This couple met and married during a time when many questioned their decision, and went on to live a beautiful life together. They’re a wonderful reminder that with the right person, you really can take on the world.

Love doesn’t have to be with a romantic partner. This story teaches us that when you invest in the things that truly matter, such as love, friendship, and meaningful connections, societal opinions can fade into the background.

In the meantime, this couple also reminds us that social media and the internet can be a wholesome place and that sometimes, just being yourself is the most powerful attraction of all.​

Copyright © 2024 Goalcast

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3.3: Fallacies

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What is a Fallacy?

Fallacies are mistakes of reasoning, as opposed to making mistakes that are of a factual nature. If I counted twenty people in the room when there were in fact twenty-one, then I made a factual mistake. On the other hand, if I believe that there are round squares, I am believing something that is inconsistent. This is a mistake of reasoning, and a fallacy, since I should not have believed something inconsistent if my reasoning is sound.

In some discussions, a fallacy is taken to be an undesirable kind of argument or inference. For example, a certain textbook explains “fallacy” as “an unreliable inference.” In our view, this definition of fallacy is rather narrow, since we might want to count certain mistakes of reasoning as fallacious even though they are not presented as arguments. For example, making a contradictory claim seems to be a case of fallacy, but a single claim is not an argument. Similarly, putting forward a question with an inappropriate presupposition might also be regarded as a fallacy, but a question is also not an argument. In both of these situations, though, the person is making a mistake of reasoning since he is doing something that goes against one or more principles of correct reasoning. This is why we would like to define fallacies more broadly as violations of the principles of critical thinking, whether or not the mistakes take the form of an argument.

The study of fallacies is an application of the principles of critical thinking. Being familiar with typical fallacies can help us avoid them. We would also be in a position to explain other people’s mistakes. There are different ways of classifying fallacies. Broadly speaking, we might divide fallacies into four kinds.

• Fallacies of inconsistency:  cases where something inconsistent or self-defeating has been proposed or accepted.
• Fallacies of inappropriate presumption:  cases where we have an assumption or a question presupposing something that is not reasonable to accept in the conversational context.
• Fallacies of relevance:  cases where irrelevant reasons are being invoked or relevant reasons are being ignored.
• Fallacies of insufficiency:  cases where the evidence supporting a conclusion is insufficient or weak.  (14)

Types of Fallacies: Fallacies of Insufficiency

Limited sampling.

• Momofuku Ando, the inventor of instant noodles, died at the age of 96. He said he ate instant noodles every day. So instant noodles cannot be bad for your health.
• A black cat crossed my path this morning, and I got into a traffic accident this afternoon. Black cats are really unlucky.

In both cases, the observations are relevant to the conclusion, but a lot more data is needed to support the conclusion. These are hasty generalizations, based on small sample sizes of data.

Appeal to Ignorance

• We have no evidence showing that he is innocent. So he must be guilty.

If someone is guilty, it would indeed be hard to find evidence showing that he is innocent. But perhaps there is no evidence to point definitively in either direction, so the lack of evidence is not enough to prove guilt.

Naturalistic Fallacy

• Many children enjoy playing video games, so we should not stop them from playing.

Many naturalistic fallacies are examples of fallacy of insufficiency. Empirical facts by themselves are not sufficient for normative conclusions, even if they are relevant.  (15)

Other Common Types of Fallacies

(Latin phrase for “against the man”)

A theory is discarded not because of any evidence against it or lack of evidence for it, but because of the person who argues for it.

This often takes the form of attacks against someone’s physical appearance.

A: The Government should enact minimum-wage legislation so that workers are not exploited. B: Nonsense. You say that only because you cannot find a good job.

ad ignorantiam

(appeal to ignorance)

The truth of a claim is established only on the basis of lack of evidence against it. A simple obvious example of such fallacy is to argue that unicorns exist because there is no evidence against such a claim.

At first sight, it seems that many theories that we describe as scientific involve such a fallacy. For instance, the first law of thermodynamics holds because so far there has not been any negative instance that would serve as evidence against it. But notice, as in cases like this, there is evidence for the law in the form of many positive instances, which therefore prove its existence.

(appeal to popularity)

The truth of a claim is established only on the basis of its popularity and familiarity. This is the fallacy committed by many commercials. Surely you have heard of commercials implying that we should buy a certain product because it has made to the top of a sales rank, or because the brand is the city’s “favorite.” In the middle of the twentieth century, tobacco manufacturers featured ads touting the number of doctors that approved of their cigarettes.

These appeals can be viewed as bandwagon appeals (everybody is doing it). Sometimes, they take the form of patriotic slogans (  Levi’s—America’s jeans  ).

Begging the question

question (petito principii)

In arguing for a claim, the claim itself is already assumed in the premise. Example: “God exists because this is what the Bible says, and the Bible is reliable because it is the word of God.”

Complex question or loaded question

A question can be fallacious if it is posed in such a way that a person, no matter what answer he or she gives, will inevitably commit him/herself to some other claim, which should not be presupposed in the context in question.

A common tactic is to ask a yes-no question that tricks people into agreeing to something they never intended to say. For example, if you are asked “Are you still as self-centered as you used to be?” then no matter whether you answer “yes” or “no,” you are bound to admit that you were self-centered in the past. Of course, the same question would not count as a fallacy if the presupposition of the question is indeed accepted in the conversational context.

False dilemma

Presenting a limited set of alternatives when there are others that are worth considering in the context. Example: “Every person is either my enemy or my friend. If he/she is my enemy, I should hate him/her. If he/she is my friend, I should love him/her. So I should either love him/her or hate him/her.” Obviously, the conclusion is too extreme because most people are neither your enemy nor your friend.

Non sequitur

A conclusion is drawn which does not follow from the premise. This is not a specific fallacy but a very general term for a poor or incomplete argument. Many of the examples in this section illustrate qualities of the non sequitur. The term roughly translates to “it does not follow,” and it can be considered a fallacy of irrelevancy if not fully defended with reasonable premises.

Example: John has a safer car than mine because it cost $10,000 more when he bought it.

Post hoc, ergo propter hoc

(literally, “after this, therefore because of this”)

Inferring that X must be the cause of Y just because X is followed by Y.

For example, having visited a graveyard, I fell ill and infer that graveyards are spooky places that cause illnesses. Of course, this inference is not warranted since this might just be a coincidence. However, a lot of superstitious beliefs commit this fallacy. Just because two events happen close to each other in terms of their timing, that doesn’t necessarily prove any causal relationship.

Red herring

Within an argument, some irrelevant issue is raised which diverts attention from the main subject. The function of the red herring is sometimes to help express a strong, biased opinion. The red herring (the irrelevant issue) serves to increase the force of the argument in a very misleading manner.

For example, in a debate as to whether God exists, someone might argue that believing in God gives peace and meaning to many people’s lives. This would be an example of a red herring since whether religions can have a positive effect on people is irrelevant to the question of the existence of God. The good psychological effect of a belief is not a reason for thinking that the belief is true.

Slippery slope

Arguing that if an opponent were to accept some claim C  1  , then he or she has to accept some other closely related claim C  2  , which in turn commits the opponent to a still further claim C  3  , eventually leading to the conclusion that the opponent is committed to something absurd or obviously unacceptable.

This style of argumentation constitutes a fallacy only when it is inappropriate to think if one were to accept the initial claim, one must accept all the other claims.

An example: “The government should not prohibit drugs. Otherwise the government should also ban alcohol or cigarettes. And then fatty food and junk food would have to be regulated too. The next thing you know, the government would force us to brush our teeth and do exercises every day.”

Attacking an opponent by attributing to him/her an implausible position that is easily defeated when this is not actually the opponent’s position. This often takes the form of a fallacy of diversion, as a speaker might abandon his or her central argument and develop a secondary argument that might seem more “winnable.” For instance, a parent might ask his or her daughter to mow the lawn. That child might argue that she has already cleaned her room, so she should be exempt from taking care of the lawn work. The point of contention in this example is the lawn work, so the other finished chores are immaterial to the argument at hand.

Example: When many people argue for more democracy in Hong Kong, a typical reply is to say that this is not warranted because it is wrong to think that democracy is the solution to all of Hong Kong’s problems, or to say that one should not blindly accept democracy. But those who support democracy never suggest that democracy can solve  all  problems (e.g. pollution), and they might also agree that  blindly  accepting something is rarely correct, whether it is democracy or not. Those criticisms attack implausible “strawman” positions and do not address the real arguments for democracy.  (15)

We are all guilty of brushing off these fallacies from time to time in our own discussions and arguments. In most cases, they are harmless tools in working through minor disagreements. Developing a stronger understanding of inductive and deductive reasoning and a clearer grasp of the logical fallacies will assist you in navigating these discussions and creating stronger, more convincing arguments of your own. It will also assist you with writing, researching, and developing stronger arguments in your college coursework and professional life. For more information on identifying, avoiding, and refuting flawed logic, please read the next section of this learning module, which features an essay by Dr. Rebecca Jones on various strategies for responding to arguments.  (1)

• Authored by : Florida State College at Jacksonville. License : CC BY: Attribution
• What is a Fallacy?. Authored by : Joe Lau and Jonathan Chan. Provided by : University of Hong Kong. Located at : http://philosophy.hku.hk/think/fallacy/fallacy.php . License : CC BY-NC-SA: Attribution-NonCommercial-ShareAlike
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Critical Thinking - Writing Lab Tips and Strategies: Logical Fallacies

Logical fallacies.

Fallacies are fake or deceptive arguments, arguments that may sound good but prove nothing.

Ad Hominem Argumen t :  Attacking the person instead of the argument.

Appeal to Closure :  The argument that the issue must be decided so that those involved can have "closure."

Appeal to Heaven : Arguing that one's position or action is right because God said so.  As Christians, we believe God has revealed his will through Scripture, but we can still fall into this fallacy if we attempt to justify ourselves apart from what the Bible says.  Even if we are being consistent with Scripture, we may still be accused of this fallacy.

Appeal to Pity : Urging an audience to “root for the underdog” regardless of the issues at hand.

Appeal to Tradition :  It's always been this way, it should continue to be this way.

Argument from Consequences : The fallacy of arguing that something cannot be true because if it were the consequences would be unacceptable.

Argument from Ignorance:  The fallacy that since we don’t know whether a claim is true or false, it must be false (or that it must be true).

 Argument from Inertia:  The argument to continue on as before because changing would be admitting that one is wrong and that one had sacrificed needlessly.

Argument from Motives:   The argument that someone must be wrong because their motives are wrong.  Also, the reverse: someone is right because their motives are right.

Argumentum ad Baculam:   Attempting to persuade through threats.  Also applies to indirect forms of threat.

Argumentum ex Silentio:   The fallacy that if sources remain silent or say nothing about a given subject or question this in itself proves something about the truth of the matter.

Bandwagon:   The fallacy of arguing that because "everyone" supposedly thinks or does something, it must be right.  

Begging the Question : Falsely arguing that something is true by repeating the same statement in different words.

Big Lie Technique:   Repeating a lie, slogan or deceptive half-truth over and over (particularly in the media) until people believe it without further proof or evidence.

Blind Loyalty:   Arguing something is right solely because a respected leader or source says it is right. 

Blood is Thicker than Water:    Automatically regarding something as true because one is related to (or knows and likes, or is on the same team as) the individual involved. 

Bribery:  Persuading with gifts instead of logic.

The Complex Question : Demanding a direct answer to a question containing acceptable and unacceptable parts.  Example: "Yes or no: Have you stopped beating your wife yet?"  "I never beat my--"  "Just answer me: Yes or no?"

Diminished Responsibility : The argument that one is less responsible for an action because one's judgment was altered.  Example:  "I was high, so I shouldn't be fined for speeding; it wasn't my fault."

Either-Or Reasoning:   Falsely offering only two possible alternatives even though a broad range of possible alternatives are available.

”E" for Effort:  Arguing that something must be right, valuable, or worthy of credit simply because someone has put so much sincere good-faith effort or even sacrifice and bloodshed into it.

Equivocation : Deliberately failing to define one's terms, or deliberately using words in a different sense than the one the audience will understand.

Essentializing : A fallacy that proposes a person or thing “is what it is and that’s all that it is,” and at its core will always be what it is right now (E.g., "All ex-cons are criminals, and will still be criminals even if they live to be 100."). Also refers to the fallacy of arguing that something is a certain way "by nature," an empty claim that no amount of proof can refute.

False Analogy : Incorrectly comparing one thing to another in order to draw a false conclusion. 

Finish the Job:   Arguing that an action or standpoint may not be questioned or discussed because there is "a job to be done," falsely assuming all "jobs" are never to be questioned. 

Guilt by Association:  Trying to refute someone's arguments or actions by evoking the negative ethos of those with whom one associates.

The Half Truth  (also Card Stacking, Incomplete Information).Telling the truth but deliberately omitting important key details in order to falsify the larger picture and support a false conclusion.

I Wish I Had a Magic Wand:   Regretfully (and falsely) proclaiming oneself powerless to change a bad or objectionable situation because there is no alternative.

Just in Case : Basing one's argument on a far-fetched or imaginary worst-case scenario rather than on reality. Plays on fear rather than reason.

Lying with Statistics : Using true figures and numbers to “prove” unrelated claims.

MYOB   (Mind Your Own Business) Arbitrarily prohibiting any discussion of one's own standpoints or behavior, no matter how absurd, dangerous, evil or offensive, by drawing a phony curtain of privacy around oneself and one's actions. 

Name-Calling:   Arguing that, simply because of who someone is, any and all arguments, disagreements or objections against his or her standpoint are automatically  racist, sexist, anti-Semitic, bigoted, discriminatory or hateful. 

Non Sequitur : Offering reasons or conclusions that have no logical connection to the argument at hand.

Overgeneralization:   Incorrectly applying one or two examples to all cases.

The Paralysis of Analysis : Arguing that since  all  data is never in, no legitimate decision can ever be made and any action should always be delayed until forced by circumstances. 

Playing on Emotions : Ignoring facts and calling on emotion alone.

Political Correctness   ("PC"): Proposing that the nature of a thing or situation can be changed simply by changing its name. 

Post Hoc Argument : Arguing that because something comes at the same time or just after something else, the first thing is caused by the second.

Red Herring : An irrelevant distraction, attempting to mislead an audience by bringing up an unrelated, but usually emotionally loaded issue.

Reductionism : Deceiving an audience by giving simple answers or slogans in response to complex questions, especially when appealing to less educated or unsophisticated audiences.

Reifying : The fallacy of treating imaginary categories as actual, material "things."

Sending the Wrong Message : Attacking a given statement or action, no matter how true, correct or necessary, because it will "send the wrong message." In effect, those who uses this fallacy are publicly confessing to fraud and admitting that the truth will destroy the fragile web of illusion that has been created by their lies.

Shifting the Burden of Proof: Challenging opponents to disprove a claim, rather than asking the person making the claim to defend his/her own argument.

Slippery Slope : The common fallacy that "one thing inevitably leads to another."

Snow Job :   "Proving” a claim by overwhelming an audience with mountains of irrelevant facts, numbers, documents, graphs and statistics that they cannot be expected to understand.

Straw Man : Setting up a phony version of an opponent's argument, and then proceeding to knock it down with a wave of the hand.

Taboo : Unilaterally declaring certain arguments, standpoints or actions to be not open to discussion.

Testimonial : When a standpoint or product is supported by a well-known or respected figure who is not an expert and who was probably well paid for the endorsement.

They're Not Like Us :  Arbitrarily disregarding a fact, argument, or objection because those involved "are not like us," or "don't think like us."

TINA  (There Is No Alternative): Squashing critical thought by announcing that there is no realistic alternative to a given standpoint, status or action, ruling any and all other options irrelevant and any further discussion is simply a waste of time.

Transfer : Falsely associating a famous person or thing with an unrelated standpoint.

Tu Quoque:  Defending a shaky or false standpoint or excusing one's own bad action by pointing out that one's opponent's acts or personal character are also open to question, or even worse.

We Have to Do  Something : Arguing that in moments of crisis one must do something,  anything , at once, even if it is an overreaction, is totally ineffective or makes the situation worse, rather than "just sitting there doing nothing." 

Where there’s smoke, there’s fire : Quickly drawing a conclusion and/or taking action without sufficient evidence.

For more in-depth discussion of these fallacies, refer to http://utminers.utep.edu/omwilliamson/ENGL1311/fallacies.htm

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Pursuing Truth: A Guide to Critical Thinking

Chapter 9 informal fallacies.

A fallacy is a mistake in reasoning. A formal fallacy is a fallacy that can be identified merely by examining the argument’s form or using a tool like a truth table. An informal fallacy cannot be detected from the argument’s form. There are no foolproof tools for detecting informal fallacies. Unlike validity, these fallacies can occur in degrees. Sometimes, it is clear that a fallacy has been committed, at other times, there can be legitimate questions about whether a fallacy has been committed.

9.1 Emotions and Critical Thinking

There are two important uses of language that play an important role in critical thinking. The first is to convey information, or what is sometimes called cognitive content. The premises and the conclusion of an argument all have cognitive content. It is on the basis of the information they convey that we can evaluate them as true or false. Another use of language, however, is to express emotion, which often tends to evoke similar feelings in the audience. The emotions that are expressed by the language is its emotive content.

Good critical thinkers are persuaded by relevant cognitive content, and are not unduly persuaded by irrelevant emotive content.

9.2 Slanters

Slanters are words or phrases that are used to manipulate by using emotive language. Slanters can have both positive and negative connotations. Slanters are types of non-argumentative persuasion. Sometimes, people will use them innocently, maybe because they have passionate feelings about the subject being discussed. Other time, though, they are used because the speaker knows that he does not have a good argument for his position. They are ways for people to affect the beliefs of others without offering reasons for their positions.

9.2.1 Euphemisms and Dysphemisms

Different words and phrases passages can have the same cognitive content but differ in their emotive content. A euphemism is a positive synonym for some neutral term. A dysphemism is a negative synonym. For example, think of the words that we use to talk about the death of a pet:

• Neutral: euthanize
• Euphemism: put to sleep
• Dysphemism: ?

Euphemisms are common in the military and in advertising. Here are some examples:

• Enhanced interrogation methods
• Collateral damage
• Depopulated area
• Pre-owned, Pre-loved
• Genuine imitation leather

In other cases, a person may use a euphemism when they have been caught doing something wrong, but want to minimize the wrongness of the action. I heard a politician once, who was caught telling a falsehood, admit to having “committed terminological inexactitude.”

Dysphemisms convey a negative attitude towards something. Examples of dysphemisms include:

• Cancer stick
• Dead tree edition

9.2.2 Innuendoes

Innuendoes imply something by what is not said. A common scene in crime films has a gangster go into a store and say something like “Nice store you got. It would be a shame if anything happened to it.” Notice that he didn’t actually say he would damage the store, although he certainly implied it.

Another use of an innuendo is to condemn with faint praise. Imagine receiving a reference letter for a student applying to graduate school. The letter only says that the student was never late to class. The implication is that her punctuality is the best that can be said of her.

Finally, there is the apophasis, which is mentioning something by saying that it won’t be mentioned. For example, “I’m not going to talk about your failure to turn assignments in on time.”

9.2.3 Weaselers

A weaseler is a way of qualifying a claim in order to avoid criticism. Weaselers include words and phrases like “perhaps,” “there’s a good chance that,” and “it’s possible that.” A weaseler that is common in advertising is “up to” — “By using our diet plan, you can lose up to ten pounds in a month.” Notice that “up to ten pounds” means “no more than ten pounds.” So, if a customer loses no weight at all, then there is no grounds for a lawsuit.

9.2.4 Downplayers

A downplayer is a way of making something seem less important than it is. The most common downplayers are “mere, merely, and so-called.” A person might say, “That’s merely your opinion” to avoid having to respond with facts. A politician might talk about his opponent’s “so-called” plan to cut spending, implying that it isn’t much of a plan at all. Improper use of quotation marks can also serve as a downplayer.

9.2.5 Proof surrogate

A proof surrogate offers no real support, but just claims that support exists. Examples are using “studies show” without saying what those studies are and where they can be found. Another proof surrogate is just to say that “It’s obvious that….” Doing so implies that proof is simply not needed.

9.2.6 Hyperbole

Hyperbole is an inappropriate or extreme exaggeration. “Taking critical thinking is the most exciting thing you’ll do in your whole life!” Since it is an extreme exaggeration, no one will be fooled into believing it, so what’s the danger? The danger of hyperbole is that once the exaggeration is made, the listener is then prepared to accept a weaker version of the statement. The weaker version, compared to the extreme exaggeration, sounds more believable.

9.3 Fallacies of Ambiguity and Vagueness

An ambiguous word or phrase is one that has more than one meaning. “Bank” is an ambiguous term, it can refer to a financial institution, a riverbank, a kind of basketball or pool shot, etc. A vague term is one that does not have a precise meaning. That is, there will be cases where a vague term clearly applies, cases in which it clearly does not apply, and cases in the middle where it’s just not clear whether it applies. Terms like “rich” and “heap” are vague terms.

9.3.1 Equivocation

The fallacy of equivocation is committed by using the same term in two different senses in the same argument. Here is my favorite example:

• God is love.
• Love is blind
• Ray Charles is blind.
• Ray Charles is God.

There are several things wrong with this argument, one of them is equivocating on “blind.” To say that love is blind, is to say that people overlooks the faults of those they love. To say that Ray Charles is blind is to say that he cannot physically see anything, not that he just overlooks things.

9.3.2 Amphiboly

Amphibolies rely on syntactic ambiguities. Those are ambiguities that result from the arrangement of the words. Church bulletin bloopers are good places to find amphibolies: “The Rev. Adams spoke briefly, much to the delight of his audience.”

9.3.3 Accent

The fallacy of accent is an equivocation resulting from accenting different words in a sentence. Think about the different meanings that are implied from accenting different words in this sentence: “I didn’t take the exam yesterday.”

9.3.4 Division and Composition

The last two fallacies of ambiguity are division and composition. The fallacy of division improperly attributes a property of the whole to its parts. The fallacy of division improperly attributes a property of the parts to the whole. Here is an example of division: “That wall weighs more than 500 pounds, so each brick in it weighs more than 500 pounds.” A similar example of composition is “Each brick in that wall weighs less than a pound, so the entire wall weighs less than a pound.”

Some properties, however, can be attributed from the parts to the whole or the whole to the parts. For example, “Each link in that chain is solid gold, so the whole chain is solid gold.”

9.3.5 Line-Drawing Fallacy

The line-drawing fallacy is a fallacy of vagueness, having the form “Since there is no precise line that can be drawnd between A and not-A, there is no real difference between A and not-A.” Example: “Since no one can say where the line should be drawn between legitimate uses of force and excessive uses of force, then no one can honestly claim that any use of force is excessive.”

9.4 Fallacies of Relevance

A good critical thinker will offer arguments that have premises that are logically relevant to their conclusions. A fallacy of relevance is committed when the premises of the argument are not logically relevant to the truth of the conclusion. They may be, however, psychologically relevant, so that we can be deceived in thinking that the argument is valid, when in fact it is not.

9.4.1 Ad Hominem

The Ad Hominem fallacy is committed by attacking the person giving the argument, rather than responding to the argument itself. There are four common types:

9.4.1.1 Personal Attack

This is also known as an ad hominem abusive. This is committed when one verbally attacks the person giving the argument instead of responding to the argument itself. For example:

Jack: “There are so many unexplored planets out there. Surely, there must be life somewhere out there”

Jill: “You can’t be right, you’re just a loser who watches too much television.”

9.4.1.2 Circumstantial Ad Hominem

A person commits the circumstantial ad hominem by referring to circumstances that discredit the arguer. This is often a charge of bias or vested interest. A person has a vested interest when they stand to gain, financially or otherwise, by something. For example, a doctor has a vested interest in a pharmaceutical study when she owns stock in the company that produces the drug. Bias or vested interest is a good reason to examine an argument carefully, but not a good reason to simply dismiss it.

Jill: John has made an excellent case for increasing the budget of the church’s youth program.

Jack: Of course he would say that — he’s the youth minister! You can just forget everything he said.

9.4.1.3 Tu Quoque

This is also known as a pseudorefutation. It accuses the arguer of hypocrisy. Example: “Don’t tell me I shouldn’t start smoking. I know how many packs a day you inhale!”

A person’s behavior may very well be inconsistent with their argument, but that doesn’t mean that the argument is bad.

9.4.1.4 Poisoning the Well

Poisoning the well is an ad hominem committed before the arguer has spoken. The goal is to provide harmful information about the speaker to preemptively discredit anything that the speaker might say. Any of the previous examples can be turned into examples of poisoning the well. For example: “John is about make his case for increasing the church’s youth budget. Don’t pay any attention to him — he’s the youth minister, what else would he say?”

9.4.2 Appeal to Force

The appeal to force, also called scare tactics, is a threat, either explicit or implicit. For example, imagine a student saying to a professor, “I deserve an A because my father is a major donor to this university and a very good friend of the dean.” The appeal to force tries to instill fear in the listener, and to be fallacious, the fear must be irrelevant to the truth of the claim. These are common in both advertising and politics. An example of an appeal to force in advertising would be an ad for a Medicare supplement policy with an elderly woman weeping in front of a pile of unpaid bills. The advertisement works by making the viewer afraid of ending up like the person in the commercial.

9.4.3 Appeal to Pity

The appeal to pity is like the appeal to force, except that the goal is to evoke pity, not fear. For example: “I deserve an A because my mother is very ill, and I had to spend most of my time caring for her this semester.”

9.4.4 Popular Appeal

This is also called appeal to the people. Here, the goal is to use the desire to be loved, admired, accepted, etc. to get others to accept the conclusion. Two important types are the bandwagon fallacy and the appeal to vanity.

9.4.4.1 Bandwagon

The bandwagon fallacy tells the listener that since everyone does, or believes, something, then they should too.

Example: “Everyone supports Smith for president. You need to get with the program and support him too!”

9.4.4.2 Appeal to Vanity

This is a claim that you will be admired if you do this. Unlike bandwagon, which claims that everyone does this, the appeal to vanity is usually about something that not everyone can do or have.

Example: “Wear a Rolex — that way everyone will know that you’re not just somebody.”

9.4.5 Appeal to Ignorance

9.4.5.1 burden of proof.

On most issues, one side will have the burden of proof. That means that if that side fails to make its case, then the other side wins by default. There are two standard rules for determining burden of proof:

• Especially for existence claims, the side making the positive case has the burden of proof.
• The side making the more implausible claim has the burden of proof.

Sometimes, these conditions can conflict. Here is an example:

Jill: Surely, there are species of insects that we have not yet discovered.

Jack: I don’t think that’s true.

Who has the burden of proof? Jill is making a positive existence claim, but it is one that very plausible. That makes Jack’s claim very implausible. In this case, I’d say that Jack has the burden of proof.

9.4.5.2 The Law

One area where these rules do not apply is the American legal system. There, the prosecution always has the burden of proof. That is, if the prosecution fails to make its case against the defendant, then the defense wins.

Burden of proof should not be confused with standard of proof. Burden of proof is concerned with who needs to make their case. Standard of proof is concerned with how strong a case needs to be made. There are four different levels of standard of proof in the law:

• Beyond a reasonable doubt
• Clear and convincing evidence
• Preponderance of evidence
• Probable cause

Criminal cases use the highest standard of proof, which is “beyond a reasonable doubt.” This is a high degree of probability. It does not mean that no doubt at all is possible, but that any doubt, given the evidence, would be unreasonable. The next two level are used in civil cases. Most civil cases are tried at the “preponderance of evidence” level. This means that, given the evidence, it is more likely that the defendant is liable than not. Clear and convincing evidence is a standard of proof between preponderance of evidence and beyond a reasonable doubt. It is used in civil cases that involve the potential loss of important rights or interests, such as the termination of potential rights. The lowest standard of proof is probable cause. This is used to determine if a search or arrest is warranted, and also used by grand juries to issue indictments.

9.4.6 Straw Man

The straw man fallacy Distorts a position so that it can be easily attacked. It does not address the actual view held by the opponent, but responds to a weaker version. It is often committed by making the conclusion of an argument more extreme than it actually is, since extreme views are often easy to attack.

Example: “Senator Snodgrass has argued that there be a mandatory waiting period before any handgun purchase. Obviously, the senator wants to make all firearm ownership illegal.”

Here some subtle ways of committing the fallacy:

• Taking words out of context.
• Treating extreme views as representative.
• Criticizing early versions of a position.
• Criticizing deliberately simplified versions of a position.

9.4.7 Red Herring

The goal of the red herring fallacy is to lead the opponent off the track, by subtly changing the issue being discussed. The arguer changes the subject to a different but related one. To determine if something is a red herring, ask yourself if the issue at the beginning of the argument is the same as the issue at the end. Here is an example:

The American Cancer Society has argued that smoking is bad for your health. Many people in the Southeastern United States are dependent upon the tobacco industry for their jobs. Making smoking illegal would have a devastating economic effect on many states. Therefore, the ACS is simply wrong.

Notice the original isse is whether smoking has bad health consequences. By the end of the paragraph, the issue has been changed to the economic impact of making smoking illegal.

9.4.8 Horse Laugh

This occurs when someone simply ridicules the position held, and offers no real response to the argument at all. For example: “Mr. Jones has argued that watching television is emotionally unhealthy. If you believe that, then I’ve got a great deal on some swampland for you.”

9.5 Fallacies of Unwarranted Assumptions

9.5.1 begging the question.

An argument begs the question if it is impossible to believe at least one of the premises unless one already believes the conclusion. Note that if this is the case, then the premises cannot serve as reasons to believe the conclusion, since believing the premises requires already believing the conclusion. There are three common types of arguments that beg the question.

The first is a circular argument. That occurs when one explicitly uses the conclusion as support for one of the premises. Here is an example:

• The Bible says that God exists.
• The Bible is the inspired word of God.
• God exists.

The Bible can’t be the inspired word of God unless God exists, so the argument begs the question.

Another type of argument that begs the question is one that simply rephrases the conclusion and uses it as a premise. Example: “If such actions were not illegal, then they would not be prohibited by the law.” In this case, the conclusion is synonymous with one of the premises.

The last type is one that generalizes the conclusion and uses the generalized rule as a premise. Example: “Spanking children is wrong because corporal punishment is wrong.”

9.5.2 Appeal to Authority

The fallacy of appeal to authority is committed by using an pseudo-authority to support a claim. Note that it is not committed by merely appealing to an authority, but by appealing to an unqualified authority. Always ask, “Should this person know more about this subject than the average person?”

9.5.3 Loaded Question

A loaded question suggests something with the question. “Whem will you stop cheating on exams?” is a loaded question, the question implies that the person is cheating. Notice that there is no way to directly answer the question without admitting to cheating on exams.

9.5.4 False Dilemma

This is sometimes called the either-or fallacy. This happens when a person asserts a disjunction, a sentence of the form "either A or B , when there is at least one more option that is true. Disjunctions are true whenever at least one of the disjuncts, the sentences joined by the ‘or,’ are true. A False dilemma asserts that one of the two sentences must be true when there is really a third alternative. Here are some examples:

“Either buy our personal financial guide or never have control of your finances.”

Child to parent: “Either let me go to the party or I’ll just die.”

False dilemmas are often expressed in pithy slogans on bumper stickers: “It’s my way or the highway” or “America, love it or leave it.”

Consider this example: “My opponent voted against the public schools spending bill. He must think educating our children is not important.” The claim is that either one votes for the bill or one believes that education is not important. This is a false dilemma since there may be many other reasons to vote against a particular bill.

It’s important to remember that a disjunction can be expressed as a conditional: “Either let me go to that party or I’ll die” is equivalent to “If you don’t let me go to that party, then I’ll die.” In general, P or Q is equivalent to if not-P then Q.

9.5.5 Slippery Slope

Slippery slopes rest a conclusion on a chain reaction that is not likely to occur. They generally have this form:

In order for this to be a fallacy, at least one of the conditional statements in the premises must not be likely to be true. Here’s an example: “If I fail this test, then I will fail the course. If I fail the course, then I’ll be expelled from school. If I’m expelled from school, then I’ll never be able to have a good job. If I can’t get a good job, then I can’t support a family…”

To test for a slippery slope, just ask, are there any weak links in this chain of conditionals? Is it really the case that one failed exam will result in an F for a course grade?

Effectiviology

Logical Fallacies: What They Are and How to Counter Them

• A logical fallacy is a pattern of reasoning that contains a flaw, either in its logical structure or in its premises.

An example of a logical fallacy is the false dilemma , which is a logical fallacy that occurs when a limited number of options are incorrectly presented as being mutually exclusive to one another or as being the only options that exist, in a situation where that isn’t the case. For instance, a false dilemma occurs in a situation where someone says that we must choose between options A or B, without mentioning that option C also exists.

Fallacies, in their various forms, play a significant role in how people think and in how they communicate with each other, so it’s important to understand them. As such, the following article serves as an introductory guide to logical fallacies, which will help you understand what logical fallacies are, what types of them exist, and what you can do in order to counter them successfully.

Examples of logical fallacies

One example of a logical fallacy is the ad hominem fallacy , which is a fallacy that occurs when someone attacks the source of an argument directly, without addressing the argument itself. For instance, if a person brings up a valid criticism of the company that they work in, someone using the ad hominem fallacy might reply by simply telling them that if they don’t like the way things are done, then that’s their problem and they should leave.

Another example of a logical fallacy is the loaded question fallacy , which occurs when someone asks a question in a way that presupposes an unverified assumption that the person being questioned is likely to disagree with. An example of a loaded question is the following:

“Can you get this task done for me, or are you too busy slacking off?”

This question is fallacious, because it has a flawed premise, and specifically because it suggests that if the person being questioned says that they can’t get the task done, then that must be because they’re too busy slacking off.

Finally, another example of a logical fallacy is the argument from incredulity , which occurs when someone concludes that since they can’t believe that a certain concept is true, then it must be false, and vice versa. For instance, this fallacy is demonstrated in the following saying:

“I just can’t believe that these statistics are true, so that means they must be false.”

In this case, the speaker’s reasoning is fallacious, because their premises are flawed, and specifically their assumption that if they can’t believe the statistics that they’re shown are true, then that must mean that the statistics are false.

Formal and informal logical fallacies

There are two main types of logical fallacies:

• Formal fallacies. A formal logical fallacy occurs when there is a flaw in the logical structure of an argument, which renders the argument invalid and consequently also unsound . For example, a formal fallacy can occur because the conclusion of the argument isn’t based on its premises.
• Informal fallacies. An informal logical fallacy occurs when there is a flaw in the premises of an argument, which renders the argument  unsound , even though it may still be valid . For example, an informal fallacy can occur because the premises of an argument are false , or because they’re unrelated to the discussion at hand.

Therefore, there are two main differences between formal and informal logical fallacies. First, formal fallacies contain a flaw in their logical structure , while informal fallacies contain a flaw in their premises . Second, formal fallacies are invalid patterns of reasoning (and are consequently also unsound), while informal fallacies are unsound patterns of reasoning, but can still be valid.

For instance, the following is an example of a formal fallacy :

Premise 1: If it’s raining, then the sky will be cloudy. Premise 2: The sky is cloudy. Conclusion:  It’s raining.

Though both the premises in this example are true, the argument is invalid , since there is a flaw in its logical structure.

Specifically, premise 1 tells us that if it’s raining, then the sky will be cloudy, but that doesn’t mean that if the sky is cloudy (which we know it is, based on premise 2), then it’s necessarily raining. That is, it’s possible for the sky to be cloudy, without it raining, which is why we can’t reach the conclusion that is specified in the argument, and which is why this argument is invalid, despite the fact that its premises are true.

On the other hand, the following is an example of an informal fallacy :

Premise 1: The weatherman said that it’s going to rain next week. Premise 2: The weatherman is always right. Conclusion:  It’s going to rain next week.

Here, the logical structure of the argument is valid. Specifically, since premise 1 tells us that the weatherman said that it’s going to rain next week, and premise 2 tells us that the weatherman is always right, then based on what we know (i.e. on these premises), we can logically conclude that it’s going to rain next week.

However, there is a problem with this line of reasoning, since our assumption that the weatherman is always right (premise 2) is false . As such, even though the logical structure of the argument is valid, the use of a flawed premise means that the overall argument is unsound .

Overall, a sound argument is one that has a valid logical structure and true premises. A formal logical fallacy means that the argument is invalid, due to a flaw in its logical structure, which also means that it’s unsound. An informal logical fallacy means that the argument is unsound, due to a flaw in its premises, even though it has a valid logical structure.

Example of a formal logical fallacy

As we saw above, a formal fallacy occurs when there is an issue with the logical structure of an argument, which renders the argument invalid.

An example of a formal logical fallacy is the masked-man fallacy , which is committed when someone assumes that if two or more names or descriptions refer to the same thing, then they can be freely substituted with one another, in a situation where that’s not the case. For example:

Premise 1: The citizens of Metropolis know that Superman saved their city. Premise 2: Clark Kent is Superman. Conclusion: The citizens of Metropolis know that Clark Kent saved their city.

This argument is invalid, because even though Superman is in fact Clark Kent, the citizens of Metropolis don’t necessarily know Superman’s true identity, and therefore don’t necessarily know that Clark Kent saved their city. As such, even though both the premises of the argument are true, there is a flaw in the argument’s logical structure, which renders it invalid.

Example of an informal logical fallacy

As we saw above, an informal fallacy occurs when there is a flaw in the premises of an argument, which renders the argument unsound.

An example of an informal logical fallacy is the  strawman fallacy , which occurs when a person distorts their opponent’s argument, in order to make it easier to attack. For example:

Alex: I think we should increase the education budget. Bob: I disagree, because if we spend the entire budget on education, there won’t be any money left for other essential things.

Here, Bob’s argument is valid from a formal, logical perspective: if we spend the entire budget on education, there won’t be anything left to spend on other things.

However, Bob’s reasoning is nevertheless fallacious, because his argument contains a false, implicit premise, and namely the assumption that when Alex suggests that we should increase the education budget, he means that the entire budget should be allocated to education. As such, Bob’s argument is unsound, because it relies on flawed premises, and counters an irrelevant point that his opponent wasn’t trying to make.

Fallacious techniques that aren’t logical fallacies

The term ‘fallacious’ has two primary meanings:

• Containing a logical fallacy.
• Tending to deceive or mislead.

Accordingly, some misleading rhetorical techniques and patterns of reasoning can be described as “fallacious”, even if they don’t contain a logical fallacy.

For example, the Gish gallop is a fallacious debate technique, which involves attempting to overwhelm your opponent by bringing up as many arguments as possible, with no regard for the relevance, validity, or accuracy of those arguments. Though a Gish gallop may have some arguments that contain logical fallacies, it isn’t a single argument by itself, and therefore isn’t considered a logical fallacy. However, because its overall argumentation pattern revolves around the intent to deceive, this technique is said to be fallacious.

In this regard, note that logical fallacies, in general, tend to include a form of reasoning that is not only logically invalid or unsound in some way, but that is also misleading.

However, it’s important to keep in mind that fallacies and other fallacious techniques aren’t always used with the intention of misleading others. Rather, people often use fallacious arguments unintentionally, both when they’re talking to other people, as well as when they conduct their own internal reasoning process, because the fact that such arguments are misleading can lead those who use them to not notice that they’re flawed in the first place.

Logical fallacies are different from factual errors

It’s important to note that logical fallacies are errors in reasoning, rather than simple factual errors.

For example, though the statement “humans are birds” is flawed, that’s because it contains a simple factual error, rather than a logical fallacy. Conversely, the argument “humans have eyes, and birds also have eyes, therefore humans are birds” contains a logical fallacy, since there is a flaw in its logical structure, which renders it invalid.

How to counter logical fallacies

To counter the use of a logical fallacy, you should first identify the flaw in reasoning that it contains, and then point it out and explain why it’s a problem, or provide a strong opposing argument that counters it implicitly.

For example, consider a situation where someone uses the appeal to nature , which is an informal logical fallacy that involving claiming that something is either good because it’s considered ‘natural’, or bad because it’s considered ‘unnatural’.

Once you’ve identified the use of the fallacy, you can counter it by explaining why its premises are flawed. To achieve this, you can provide examples that demonstrate that things that are “natural” can be bad and that things that are “unnatural” can be good, or you can provide examples that demonstrate the issues with trying to define what “natural” and “unnatural” mean in the first place.

The steps in this approach, where you first identify the use of the fallacy and then either explain why it’s a problem or provide strong counterarguments, are generally the main ones to follow regardless of which fallacy is being used. However, there is some variability in terms of how you implement these steps when it comes to different fallacies and different circumstances, and an approach that will work well in one situation may fail in another.

For example, while a certain approach might work well when it comes to resolving a formal fallacy that you’ve used unintentionally in your own reasoning process, the same approach might be ineffective when it comes to countering an informal fallacy that was used intentionally by someone else for rhetorical purposes.

Finally, it’s also important to keep in mind that sometimes, when responding to the use of fallacious reasoning, dismantling the logic behind your opponent’s reasoning and highlighting its flaws might not work. This is because, in practice, human interactions and debates are highly complex, and involve more than just exchanging logically sound arguments with one another.

Accordingly, you should accept the fact that in some cases, the best way to respond to a logical fallacy in practice isn’t necessarily to properly address it from a logical perspective. For example, your best option might be to modify your original argument in order to counter the fallacious reasoning without explicitly addressing the fact that it’s fallacious, or your best option might be to refuse to engage with the fallacious argument entirely.

Account for unintentional use of fallacies

When you counter fallacies that other people use, it’s important to remember that not every use of a logical fallacy is intentional, and to act accordingly, since accounting for this fact can help you formulate a more effective response.

A useful concept to keep in mind in this regard is  Hanlon’s razor , which is a philosophical principle that suggests that when someone does something that leads to a negative outcome, you should avoid assuming that they acted out of an intentional desire to cause harm, as long as there is a different plausible explanation for their behavior. In this context, Hanlon’s razor means that, if you notice that someone is using a logical fallacy, you should avoid assuming that they’re doing so intentionally, as long as it’s reasonable to do so.

In addition, it’s important to remember that you too might be using logical fallacies unintentionally in your thinking and in your communication with others. To identify cases where you are doing this, try to examine your reasoning, and see if you can identify any flaws, either in the way that your arguments are structured, or in the premises that you rely on in order to make those arguments. Then, adjust your reasoning accordingly, in order to fix these flaws.

Make sure arguments are fallacious before countering

Before you counter an argument that you think is fallacious, you should make sure that it is indeed fallacious, to the best of your ability.

There are various ways to do this, including slowing down your own reasoning process so you can properly think through the argument, or asking the person who proposed the argument to clarify their position.

The approach of asking the other person to clarify their position is highly beneficial in general, because it helps demonstrate that you’re truly interested in what the other person has to say. Furthermore, in cases where the argument in question does turn out to be fallacious, this approach can often help expose the issues with it, and can also help the other person internalize these issues, in a way that you won’t always be able to achieve by pointing them out yourself.

Finally, note that a useful tool to remember in this regard is the principle of charity , which is a philosophical principle that denotes that, when interpreting someone’s statement, you should assume that the best possible interpretation of that statement is the one that the speaker meant to convey. In this context, the principle of charity means that you should not attribute falsehoods, logical fallacies, or irrationality to people’s argument, when there is a plausible, rational alternative available.

Remember fallacious arguments can have true conclusions

It’s important to keep in mind that even if an argument is fallacious, it can still have a true conclusion. Assuming that just because an argument is fallacious then its conclusion must necessarily be false is a logical fallacy in itself, which is known as the fallacy fallacy .

For instance, consider the following example of a formal logical fallacy (which we saw earlier, and which is known as affirming the consequent ):

Premise 1: If it’s raining, then the sky will be cloudy. Premise 2: The sky is cloudy. Conclusion: It’s raining.

This argument is logically invalid, since we can’t be sure that its conclusion is true based on the premises that we have (because it’s possible that the sky is cloudy but that it’s not raining at the same time). However, even though the argument itself is flawed, that doesn’t mean that its conclusion is necessarily false. Rather, it’s possible that the conclusion is true and that it is currently raining; we just can’t conclude this based on the premises

The same holds for informal fallacies. For example, consider the following argument:

Alex: It’s amazing how accurate this personality test I took is. Bob: No it isn’t, it’s pure nonsense.

Here, Bob is using an appeal to the stone , which is a logical fallacy that occurs when a person dismisses their opponent’s argument as absurd, without actually addressing it, or without providing sufficient evidence in order to prove its absurdity. However, even though Bob’s argument is fallacious, that doesn’t mean that its conclusion is wrong; it’s possible that the personality test in question is indeed nonsense, we just can’t tell whether that’s the case based on this argument alone.

Overall, the important thing to understand is that an argument can be fallacious and still have a conclusion that is factually correct. To assume otherwise is fallacious, which is why you shouldn’t discount people’s conclusions simply because the argument that they used to reach those conclusions contains a logical fallacy.

The difference between logical fallacies and cognitive biases

While logical fallacies and cognitive biases appear to be similar to each other, they are two different phenomena. Specifically, while logical fallacies are flawed patterns of argumentation , and are therefore a philosophical concept, cognitive biases are systematic errors in cognition , and are therefore a psychological concept.

Cognitive biases often occur at a more basic level of thinking, particularly when they’re rooted in people’s intuition, and they can lead to the use of various logical fallacies.

For example, the appeal to novelty is a logical fallacy that occurs when something is assumed to be either good or better than something else, simply because it’s perceived as being new and novel.

In some cases, people might use this fallacy due to a cognitive bias that causes them to instinctively prefer things that they perceive as newer. However, people can experience this instinctive preference for newer things without it leading to the use of the appeal to novelty, in cases where they recognize this preference and account for it properly. Furthermore, people can use arguments that rely on the appeal to novelty even if they don’t experience this instinctive preference, and even if they don’t truly believe in what they’re saying.

Overall, the main difference between logical fallacies and cognitive biases is that logical fallacies are a philosophical concept, that has to do with argumentation , while cognitive biases are a psychological concept, that has to do with cognition . In some cases, there is an association between cognitive biases and certain logical fallacies, but there are many situations where one appears entirely without the other.

Summary and conclusions

• To counter the use of a logical fallacy, you should first identify the flaw in reasoning that it involves, and then point it out and explain why it’s a problem, or provide a strong opposing argument that counters it implicitly.
• Note that there is some variability in terms of how you should counter different fallacies under different circumstances, and an approach that will work well in one situation may fail in another.
• When responding to the use of a logical fallacy, it’s important to make sure that it’s indeed a fallacy, to remember that the use of the fallacy might be intentional, and to keep in mind that just because an argument is fallacious doesn’t mean that its conclusion is necessarily wrong.
• Certain rhetorical techniques and patterns of reasoning can be described as “fallacious” even if they don’t contain a logical fallacy, because they’re used with the intent to deceive or mislead listeners.

Other articles you may find interesting:

• False Premise: When Arguments Are Built on Bad Foundations
• False Dilemmas and False Dichotomies: What They Are and How to Respond to Them
• The Fallacy Fallacy: Why Fallacious Arguments Can Have True Conclusions

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Logical Fallacies

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Fallacies are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points, and are often identified because they lack evidence that supports their claim. Avoid these common fallacies in your own arguments and watch for them in the arguments of others.

Slippery Slope: This is a conclusion based on the premise that if A happens, then eventually through a series of small steps, through B, C,..., X, Y, Z will happen, too, basically equating A and Z. So, if we don't want Z to occur, A must not be allowed to occur either. Example:

If we ban Hummers because they are bad for the environment eventually the government will ban all cars, so we should not ban Hummers.

In this example, the author is equating banning Hummers with banning all cars, which is not the same thing.

Hasty Generalization: This is a conclusion based on insufficient or biased evidence. In other words, you are rushing to a conclusion before you have all the relevant facts. Example:

Even though it's only the first day, I can tell this is going to be a boring course.

In this example, the author is basing his evaluation of the entire course on only the first day, which is notoriously boring and full of housekeeping tasks for most courses. To make a fair and reasonable evaluation the author must attend not one but several classes, and possibly even examine the textbook, talk to the professor, or talk to others who have previously finished the course in order to have sufficient evidence to base a conclusion on.

Post hoc ergo propter hoc: This is a conclusion that assumes that if 'A' occurred after 'B' then 'B' must have caused 'A.' Example:

I drank bottled water and now I am sick, so the water must have made me sick.

In this example, the author assumes that if one event chronologically follows another the first event must have caused the second. But the illness could have been caused by the burrito the night before, a flu bug that had been working on the body for days, or a chemical spill across campus. There is no reason, without more evidence, to assume the water caused the person to be sick.

Genetic Fallacy: This conclusion is based on an argument that the origins of a person, idea, institute, or theory determine its character, nature, or worth. Example:

The Volkswagen Beetle is an evil car because it was originally designed by Hitler's army.

In this example the author is equating the character of a car with the character of the people who built the car. However, the two are not inherently related.

Begging the Claim: The conclusion that the writer should prove is validated within the claim. Example:

Filthy and polluting coal should be banned.

Arguing that coal pollutes the earth and thus should be banned would be logical. But the very conclusion that should be proved, that coal causes enough pollution to warrant banning its use, is already assumed in the claim by referring to it as "filthy and polluting."

Circular Argument: This restates the argument rather than actually proving it. Example:

George Bush is a good communicator because he speaks effectively.

In this example, the conclusion that Bush is a "good communicator" and the evidence used to prove it "he speaks effectively" are basically the same idea. Specific evidence such as using everyday language, breaking down complex problems, or illustrating his points with humorous stories would be needed to prove either half of the sentence.

Either/or: This is a conclusion that oversimplifies the argument by reducing it to only two sides or choices. Example:

We can either stop using cars or destroy the earth.

In this example, the two choices are presented as the only options, yet the author ignores a range of choices in between such as developing cleaner technology, car-sharing systems for necessities and emergencies, or better community planning to discourage daily driving.

Ad hominem: This is an attack on the character of a person rather than his or her opinions or arguments. Example:

Green Peace's strategies aren't effective because they are all dirty, lazy hippies.

In this example, the author doesn't even name particular strategies Green Peace has suggested, much less evaluate those strategies on their merits. Instead, the author attacks the characters of the individuals in the group.

Ad populum/Bandwagon Appeal: This is an appeal that presents what most people, or a group of people think, in order to persuade one to think the same way. Getting on the bandwagon is one such instance of an ad populum appeal.

If you were a true American you would support the rights of people to choose whatever vehicle they want.

In this example, the author equates being a "true American," a concept that people want to be associated with, particularly in a time of war, with allowing people to buy any vehicle they want even though there is no inherent connection between the two.

Red Herring: This is a diversionary tactic that avoids the key issues, often by avoiding opposing arguments rather than addressing them. Example:

The level of mercury in seafood may be unsafe, but what will fishers do to support their families?

In this example, the author switches the discussion away from the safety of the food and talks instead about an economic issue, the livelihood of those catching fish. While one issue may affect the other it does not mean we should ignore possible safety issues because of possible economic consequences to a few individuals.

Straw Man: This move oversimplifies an opponent's viewpoint and then attacks that hollow argument.

People who don't support the proposed state minimum wage increase hate the poor.

In this example, the author attributes the worst possible motive to an opponent's position. In reality, however, the opposition probably has more complex and sympathetic arguments to support their point. By not addressing those arguments, the author is not treating the opposition with respect or refuting their position.

Moral Equivalence: This fallacy compares minor misdeeds with major atrocities, suggesting that both are equally immoral.

That parking attendant who gave me a ticket is as bad as Hitler.

In this example, the author is comparing the relatively harmless actions of a person doing their job with the horrific actions of Hitler. This comparison is unfair and inaccurate.