We've listed the Top 10 Logical Fallacies that are among the most commonly used. This list of fallacies includes explanations and examples of each kind of fallacy. These are all informal fallacies.
This is our article in the Art to Argument series, which teaches logical fallacies and techniques of persuasion.
For classical persuasion techniques, see our article How to be Persuasive in Making Arguments: Ethos, Pathos, and Logos.
Familiarizing yourself with the top 10 most common logical fallacies can be helpful to avoid them and improve your debate skills. But learning these common logical fallacies will also allow you to recognize when your opponent is using them and not making a logical argument. You'll be able to recognize these fallacies and call them by name.
Fallacies are usually formally studied within college Philosophy or Communication programs, in classes which study logic and rhetoric.
What are Logical Fallacies?
Logical Fallacies are flawed reasoning creating false arguments, or arguments constructed wrongly.
Samuel Johnson's definition:
"Sophism; logical artifice; deceit; deceitful argument; delusory mode of ratiocination."Samuel Johnson's Dictionary
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The Top 10 Logical Fallacies
1. Straw Man Argument
The Straw Man: This occurs when someone is misrepresenting the position of their opponent. This is done by replacing their position with a different position, and then attacking that different position (attacking the straw man). Changing the opposing position is called that because a man made of straw is a weak target and easier to defeat.
This sets up a false version of the opponent's argument, and then works at defeating the false version.
Meanwhile, the actual argument of the opponent hasn't been addressed at all. Arguments cannot be conducted under these fallacious conditions because the content of the argument itself isn't actually being addressed or contended with.
Mary says "This is the best Thai food restaurant in the city." John responds with "You think this is the best restaurant in the city?"
How to avoid it:
Make sure that you understand your opponents position clearly. Restate it to the opponent and ask if what you stated is an accurate representation of their argument's position. This will also prevent against them changing their position later on.
2. Begging the Question (circular argument)
Begging the question occurs when someone re-states or reaffirms the premise (or premises) as the conclusion (without any further explanation or information).
The problem with this is that it never progresses the argument past the premise or premises.
The premises are simply reasserted as the conclusion. Or, the conclusion is put into the premises, and then reasserted as the conclusion.
The premise of an argument has to be different in content and meaning than the conclusion. And the conclusion has to be separate in content and meaning than the premise(s), albeit related through logical coherence.
Mary says "John always tells the truth." Bob asks "How do you know?" Mary responds "Because John says that he always tells the truth." Of course John's honesty is what's in question, and John speaking on his own behalf begs the question. This is a circular argument because the conclusion is really just the premise restated.
How to avoid Begging the Question:
Make sure that the conclusion isn't just restating the premise or one of the premises. This means thinking about and comparing the premise and conclusion with each other.
3. Ad Hominem Argument
Someone uses an Ad Hominem fallacy when they're attacking the person and not their argument. One example is saying that the identity or some quality of a person disqualifies them from making any valid points.
It's attacking a person, which can include their identity or personal character (such as their physical appearance), instead of attacking their actual position. This is common in political debate.
Cliff cannot be correct when he says that squares have right angles because he is a bad person and has been known to steal ideas and credit them for himself. The position that squares have right angles (or not) has not been addresses, and has been left untouched.
You can see this playing out in the political sphere in modern American politics, with a statement such as "You say that guns are harmless inert objects because you are a Republican", or "Your argument about guns being the problem is wrong because you're a Democrat", etc.
How to avoid it:
Make sure that you're not attacking the person and that you're actually contending with the content of their argument. Leave out any personal biases or irrelevant personal characteristics of the opponent that have nothing to do with the content of their argument. A person can be a bad person in any number of ways and still be logically correct in any given instance.
This argument technique is also called "Bulverism", as described in an essay written by C. S. Lewis, which you can watch on YouTube.
4. Post Hoc "post hoc ergo propter hoc" (after this, therefore because of this)
This occurs when someone assumes causality from an order of events. Claiming that since B always happens after A, then A must cause B, is the problem. Order of events doesn't necessarily mean causation.
Actual causation would remain unexplained by only attending to a sequence or order of events. The sequence of events needs actual causation to be understood in order for causation claims to be made.
Incidents of burglars breaking into cars rises whenever the sun is shining, and declines when it's raining outside. Therefore, sunny days cause crime.
How to avoid it:
The best way to avoid this is to think about whether you actually understand the causal agent or causal story, and that you're not inferring causing from the order of events. If you realize that you don't know the cause of the phenomena, it's best to just suspend judgments until the cause is known.
5. Loaded Question
This occurs whenever a person asks a question which includes their desired outcome, against the position of the person answering the question.
The classic example of a Loaded Question is "Are you still beating your wife?" Whether the person answers yes or no, the person is framed as a wife beater, whether they are or not.
This is also a tactic often used with lawyers when they're leading the witness by asking questions to guide the witness to certain conclusions that the lawyer is trying to attain.
How to avoid it:
This should be easy to avoid since it is usually done intentionally.
6. False Dichotomy (False Dilemma, Either/Or)
A False Dichotomy is an informal fallacy. This occurs when the arguer is presenting only two possible options or outcomes to a position, when in reality there are more options.
It's done to narrow the opponent's position to only two possible outcomes. It's an argument tactic designed to lead to intentionally chosen narrowed and specific options.
Mom tells her child "Do you want to go to sleep now or in 5 minutes?" The false dilemma is that there are more options than now or in 5 minutes, such as going to bed in 10 minutes. Most kids pick up on this tactic used by parents when they're still in toddlerhood.
How to avoid it:
Think about whether the options you're considering do indeed exhaust all of the possibilities, or if there are other legitimate possibilities to consider as well. Think about alternatives before the list of possibilities is narrowed to only two or one.
7. Equivocation (Doublespeak)
Equivocation is an informal fallacy. To Equivocate means to use language in a wrong or misleading way to either conceal a truth or to avoid being committed to a position. The goal behind this fallacy is to mislead the listener through a manipulation of language. Often the meaning of a word is changed mid-argument to serve the purposes of the one who is being misleading.
Equivocate is to make an incorrect equivalence between words (or concepts that are at issue within the argument).
An example of equivocating would be to use the word "right" in two ways within an argument: right as in morally correct, and right as in functionally correct (such as the right tool to use for the job).
How to avoid it:
Use your words in consistent ways without shifting meanings.
8. Appeal to Authority (ad verecundiam)
Appeal to authority is an informal fallacy. Making an appeal to an authority in an argument doesn't make the argument correct. An appeal to authority can be correct, or incorrect, depending on the substance of the claim that's at issue.
There are experts (authorities) on opposing sides of court cases. They can both be right in certain domains, or within the same domain one can be more correct than the other. Being an expert on a given topic doesn't mean that anything that the expert claims is therefore correct.
Mary says "The earth is flat." Bob says "How do you know that?" Mary says "Because my geology teacher told me." It's doubtful that a geology teacher would actually teach this but it illustrates the fallacy.
How to avoid it:
Don't appeal to any authority as the basis for the legitimacy of your claim.
9. Hasty Generalization
Hasty Generalization is an informal fallacy. Making a claim about something without sufficient or unbiased evidence for the claim. If the evidence did support the claim, then it would just be a generalization. The hasty description means that the generalization was done too quickly and without evidence.
This is a tricky one because there is no agreed upon threshold of what constitutes a sufficient number of examples or sample size to be considered as legitimate evidence in any given case. Is it more than 50%? However, it can usually be more easily determined as to what constitutes biased or unbiased evidence.
John says "You're a musician, so therefore you must not have stage fright."
How to avoid it:
Consider what the evidence is, and how large the sample size is, and whether they're sufficient to be representative of the whole before making the claim.
10. Appeal to Popular Opinion (Argumentum ad populum)
Appeal to popular opinion is an informal fallacy. This fallacy occurs when someone is making an argument that a position is true because a great number (or the majority) of people hold to that position. The fallacy here is that the majority may be factually wrong as a result of being misled or having partial information and drawing wrong conclusions.
We've seen this in history, in which the majority of people have been misled by their media or by their government or by wrong scientific or philosophical assumptions.
Medieval John says "The sun revolves around the earth, and the earth is fixed in place." Medieval Mary says "How do you know that the sun revolves around a fixed earth?" To which Medieval John replies "Don't you know that everyone believes that the earth is fixed in place, around which the sun revolves? It's common knowledge."
How to avoid it:
Consider the merits of the statements on their own grounds without recourse to what others think about it.
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Informal Fallacies Are Not Always Fallacious
For example, the Slippery Slope will be fallacious if the argument's conclusion doesn't occur. For example: “If you invest all of your grandmother's inheritance money into buying NFTs, you will lose it all, then you wont be able to buy a car, and if you don't have a car, you can't go to work, and if you can't go to work you won't be able to move out of your mother's house.”
This Slippery Slope becomes fallacious if the person spends all of their inheritance money on NFTs and the following events do not occur. But what if these events do come true, and in exactly this manner? In other words, the Slippery Slope isn't always or necessarily fallacious. It is merely making predictions based on an initial step and circumstance.
That prediction may come true as a consequence of that first step down the slope. Such is the nature of informal fallacies. They may be wrong, but they may also be right. It depends on what's at issue.
However, one caveat is that there are certain informal fallacies that are likely always fallacious, such as the Ad Hominem fallacy.
Another example, the Appeal to Authority may be appropriate and valid if the authority is qualified and makes factual assertions in whatever is at issue. Such is the nature of Informal Fallacies - they're only fallacious if the reasoning is faulty.
Formal fallacies are always fallacious because the structure itself is formed incorrectly. There are only a relatively small number of these fallacies by comparison.
A logical conclusion is when the premises are true and the particular conclusion logically follows. These premises often have supporting evidence presented.
What Are Informal Fallacies?
These are created by faulty logic, where the conclusion doesn't follow logically from the premise(s). Either there is a problem with the premise(s), such as insufficient, biased, or irrelevant evidence, or a problem with the conclusion.
There may be no logical connection from the premise to the conclusion, the conclusion goes too far or not far enough, is irrelevant, or there is not enough evidence and obviously needs to establish more evidence. These arguments can have the proper logical construction, but still be fallacious.
What Are Formal Fallacies?
When an argument is wrongly constructed is known as a Formal Fallacy. These arguments are formally wrong by their formulation. These logical fallacies break the rules of logic in the way that they're constructed. This is a matter of recognizing a problem in the structure.
Frequently Asked Questions
What are examples of logical fallacies?
Straw Man Fallacy, Begging the Question Fallacy, Ad Hominem Fallacy, Post Hoc Fallacy "post hoc ergo propter hoc" (after this, therefore because of this) Fallacy, Loaded Question Fallacy, False Dichotomy (False Dilemma, Either/Or) Fallacy, Equivocation (Doublespeak) Fallacy, Appeal to Authority (ad verecundiam) Fallacy, Hasty Generalization Fallacy, and Appeal to Popular Opinion (ad populum) Fallacy.
How would you explain a logical fallacy?
As an argument in which the conclusion doesn't follow from the premise or premises. The premises could be wrong, or the conclusion could be wrong, or both. First, identify which logical fallacy is being used. From there you can describe the fallacy by giving a hypothetical example that your listener will understand. An over-exaggerated example works best, because it draws-out, by exaggeration, where in the argument the fallacy is.
Then you can explain exactly how (at the over-exaggerated point) the break in logic occurred, and how the conclusion isn't supported by the premise(s). For example, with a Straw Man fallacy, you can make another Straw Man type of argument that's more directly obvious as being fallacious by grossly misrepresenting the opponent's position. This should illustrate the point of where the mistake occurred.
What makes a logical fallacy?
What makes an Informal Logical Fallacy is an incorrect conclusion reached through faulty thinking. Said another way, reaching a conclusion that is not supported by the premises. You may have correct premises, but yet through faulty reasoning you've arrived at an incorrect conclusion. A Formal Fallacy occurs when the argument itself is constructed wrongly. The premises may be true, but the argument is fallacious because the formal construction is faulty.
Is generalization a logical fallacy?
Hasty Generalization is a logical fallacy. The relevant part of this is the "hasty' nature of the generalization, which means generalizing the group erroneously and without supported evidence, based on the particulars of a few within that group. As explained above, it's "Making an unwarranted claim about the group from the particulars or characteristics of a select few within the group." Generalization by itself is not necessarily a fallacy. You would have to look at what's being generalized, and on what grounds the generalization is based.
What is a fallacy example?
Appeal to Authority Fallacy: appealing to an authority in an argument doesn't settle the question of the cogency of the argument at hand. Authorities can be wrong. As explained above: The authority's bona fides needs to be established. Even then it can be fallacious to cite them as an authority, depending on the authority's claim.
This one is tricky because it depends on the circumstances and scenario. There are experts (authorities) on opposing sides of court cases. They can both be right in certain domains, or within the same domain one can be more right than the other. The fallacy would be to make more of a claim than just an expert opinion.
Why are logical fallacies important?
Knowing and understanding logical fallacies is important because it stops the exchange of untruth. They're only so good as they root out what's not true, so that, when determined, an argument ceases to be valid, and hopefully ceases to be asserted and/or believed. It's also important because identifying where the mistake in logic occurred allows for correction. Logical fallacy identification is the corrective for bad argumentation.
How do you respond to a logical fallacy?
The best way to respond to a logical fallacy is to identify it by name, and then explain what the fallacy is, and how it was used, and where it occurred in the argument.
Why should you avoid logical fallacies?
You should avoid logical fallacies to make true arguments, or at least arguments that aren't false in their formulation or reasoning. The point of avoiding logical fallacies it to make valid arguments. The point of making valid arguments is to interpret and navigate the world and all of its facets correctly and without logical errors.
What is the best way to prevent making logical fallacies in arguments?
The best way to avoid making logical fallacies is first to learn the most common fallacies. Secondly, and just as important, is to assess your own arguments, and see if the arguments you're making are using any logical fallacy, and if so, which one(s)? This requires self-assessment, analyses, and reflection. The goal is to be able to have an ongoing ability to determine this as the argument is being made (not after the fact, but while the conversation is occurring). It requires having an internal monitor as to the cogency of what you're saying or writing.
What's the difference between a Formal and Informal Fallacy?
Formal Fallacy: A formal fallacy occurs when the structure of the argument itself is flawed, by being constructed wrongly. Informal Fallacy refers to faulty or erroneous reasoning within a proper logical construction. In an Informal Fallacy, there is some form of erroneous reasoning involved that undermines the argument.
What does the word Fallacy mean?
The word Fallacy is a derivative of the Latin word fallacia, which meant to trick or be deceptive. The word Fallacy in modern English means to make an error in reasoning, or a false inference. Fallacy refers to a broad category that encompasses individual kinds of fallacies, of which there are many different types. Errors in reasoning can usually be placed within these individual categories, and identified by the nature of the error itself. How the reasoning was faulty determines the category of fallacy in which the error is placed, and identifies the fallacy type.
How do you identify a logical fallacy?
There are a few ways that one may identify a logical fallacy. One way is to learn and familiarize yourself with all of the fallacy types, and thereby be able to identify on the spot which fallacy may be at issue. Another way to identify a logical fallacy is to consider whether the premise or premises are legitimate, and if the conclusion follows. If not, then either there is a premise that goes too far, or not far enough, or is irrelevant to the conclusion. Or the conclusion goes too far, or not far enough, or is irrelevant from the premises.
There are many other fallacies to consider, including:
- Slippery slope fallacy
- Causal fallacy
- Proof fallacy
- Sunk cost fallacy
- No true scotsman fallacy
- Texas sharpshooter fallacy
- Red herring fallacy
- Tu quoque fallacy
- Appeal to pity
- Bandwagon fallacy
See this for a comprehensive list of fallacies.