Ideas
Fallacies
35 common mistakes in reasoning. Each has its own page: what it is, an everyday example, how to spot it and how to answer it fairly.
All of them on one printable page
All fallacies
Ad hominemAttacking the person making an argument instead of the argument itself.
Tu quoqueDismissing a criticism because the critic does the same thing.
Genetic fallacyJudging a claim by where it came from or why someone holds it, rather than by the evidence.
Straw manReplacing someone’s argument with a weaker or more extreme version, then knocking that down.
Red herringBringing in a different issue to pull attention away from the one being discussed.
Appeal to emotionUsing feelings such as fear, pity or pride in place of reasons.
Appeal to consequencesDeciding whether something is true by whether you would like the result.
BandwagonTreating a claim as true because many people believe it.
Appeal to authorityAccepting a claim because someone famous or important said it, outside their expertise or without reasons.
Appeal to natureAssuming that what is natural is good or safe, and what is artificial is bad.
Appeal to traditionTreating a practice as right because it is old or customary.
Appeal to ignoranceClaiming something is true because it has not been proved false, or false because it has not been proved true.
Sunk cost fallacyContinuing something because of what you have already spent on it, rather than what lies ahead.
False dilemmaPresenting two options as the only ones when there are more.
Slippery slopeClaiming one small step will inevitably lead to a chain of extreme results, without showing why.
Begging the questionUsing the conclusion, in other words, as one of the reasons for it.
Loaded questionAsking a question that smuggles in an assumption, so any direct answer accepts it.
Moving the goalpostsChanging what counts as evidence after the original test has been met.
No true ScotsmanProtecting a generalization by redefining the group to exclude any counterexample.
Motte and baileyAdvancing a bold claim, retreating to a modest one when challenged, then advancing again.
Special pleadingApplying a rule to others while claiming an exception for yourself without a good reason.
EquivocationShifting between two meanings of the same word partway through an argument.
Composition and divisionAssuming what is true of the parts is true of the whole, or what is true of the whole is true of each part.
Affirming the consequentReasoning from “if A then B” and “B” to “A”, which does not follow.
Denying the antecedentReasoning from “if A then B” and “not A” to “not B”, which does not follow.
Weak analogyArguing that two things are alike in one way because they are alike in others, when the differences matter.
Post hocAssuming that because one thing happened after another, the first caused the second.
Correlation is not causationConcluding that because two things go together, one causes the other.
Hasty generalizationDrawing a general conclusion from too few or untypical cases.
Cherry-pickingShowing only the evidence that supports a claim and leaving out the rest.
Texas sharpshooterFinding a pattern in random data after the fact, then treating it as meaningful.
Survivorship biasDrawing conclusions from the cases that made it through a filter, and forgetting the ones that did not.
Gambler’s fallacyBelieving that a random event is more or less likely because of what happened just before.
Base rate fallacyIgnoring how common something is in general when judging a particular case.
Conjunction fallacyJudging a detailed story as more likely than a simpler one it contains.No fallacy matches that. Try another word, or search the whole site.
The five kinds
- Changing the subject
- Answering something other than the argument: the person, a distorted version, or a feeling.
- Leaning on the wrong support
- Treating popularity, fame, nature, habit or silence as if it were evidence.
- Rigging the question
- Building the answer into the setup, or changing the rules once the test is under way.
- Slippery words and shapes
- Arguments that look valid because of a shifting word or a borrowed shape.
- Bad evidence
- Mistakes about causes, samples and chances: the story outruns the numbers.