The Reasoning Guide

Short, linkable explanations of the reasoning mistakes that derail discussions. Find the fallacy, understand why it fails, respond well.

All fallacies by category

Relevance

Ad Hominem

Attacking the person making the argument — their character, motives, or background — instead of addressing the argument itself.

Relevance

Genetic Fallacy

Judging a claim as true or false based on its origin — who said it or where it comes from — rather than on its own merits.

Relevance

Guilt by Association

Discrediting a claim or a person because of an association with a disliked group or individual — rather than judging the claim on its merits.

Relevance

Red Herring

Introducing an irrelevant point to divert attention from the actual issue under discussion.

Relevance

Straw Man

Misrepresenting someone's argument to make it easier to attack — then knocking down the distorted version instead of what they actually said.

Relevance

Tu Quoque

Dismissing criticism by pointing out that the critic doesn't live up to it themselves. Their hypocrisy doesn't make the criticism false.

Relevance

Whataboutism

Deflecting a criticism by raising a different wrongdoing — "but what about X?" — instead of answering the point at hand.

Relevance

Causal

False Cause

Assuming that because one thing happened after another, or alongside it, the first must have caused the second.

Causal

Gambler's Fallacy

Believing that past random events change the odds of future ones — like expecting a coin to land heads because it's been tails five times.

Causal

Single Cause

Assuming a complex outcome has one single cause, when many factors contributed.

Causal

Slippery Slope

Claiming that a first step will inevitably trigger a chain of events ending in disaster, without showing each link is likely.

Causal

Texas Sharpshooter

Cherry-picking clusters in data after the fact and treating them as meaningful — like shooting a wall, then painting the target around the holes.

Causal

Ambiguity

Equivocation

Sliding between two meanings of the same word mid-argument, so the conclusion only seems to follow.

Ambiguity

Motte and Bailey

Advancing a bold claim, then retreating to a safer, obvious one when challenged — and acting as if they were the same claim all along.

Ambiguity

Moving the Goalposts

Raising the standard of evidence after it's been met, so no amount of proof can ever settle the question.

Ambiguity

No True Scotsman

Rescuing a generalization from a counterexample by redefining the group on the spot: no *real* X would do that.

Ambiguity

Presumption

Anecdotal Evidence

Using a personal story or isolated case in place of solid evidence — "my grandfather smoked and lived to 95."

Presumption

Begging the Question

Using your conclusion as one of your premises — the argument assumes the very thing it's supposed to prove.

Presumption

Burden of Proof

Making a claim and demanding others disprove it, instead of providing evidence yourself.

Presumption

Cherry Picking

Selecting only the evidence that supports your position while ignoring the evidence that contradicts it.

Presumption

False Analogy

Arguing that because two things are alike in one way, they must be alike in another — when the similarity doesn't support the conclusion.

Presumption

False Dilemma

Presenting only two options when more exist, forcing a choice between extremes.

Presumption

Hasty Generalization

Drawing a broad conclusion from a sample that's too small or unrepresentative.

Presumption

Loaded Question

Asking a question that smuggles in an unproven assumption, so any direct answer concedes it — "Have you stopped cheating?"

Presumption

Middle Ground

Assuming the truth must lie halfway between two opposing positions. Sometimes one side is simply wrong.

Presumption

Appeal

Appeal to Authority

Treating a claim as true because an authority said so — especially outside their expertise — rather than because of the evidence.

Appeal

Appeal to Consequences

Judging a claim true or false based on whether its consequences would be pleasant or unpleasant.

Appeal

Appeal to Emotion

Manipulating feelings — fear, pity, outrage — to win acceptance of a claim in place of evidence.

Appeal

Appeal to Ignorance

Treating a claim as true because it hasn't been proven false — or false because it hasn't been proven true.

Appeal

Appeal to Nature

Arguing something is good because it's natural, or bad because it's unnatural.

Appeal

Appeal to Tradition

Arguing something is right or true because it's always been done that way.

Appeal

Bandwagon

Arguing something is true or right because many people believe or do it.

Appeal

Personal Incredulity

Rejecting a claim because you personally find it hard to imagine or understand.

Appeal

Structure

Affirming the Consequent

Reasoning backwards in an if-then: "If A then B; B is true; therefore A" — but B can have other causes.

Structure

Composition and Division

Assuming what's true of the parts must be true of the whole — or what's true of the whole must be true of each part.

Structure

Denying the Antecedent

Reasoning in an if-then: "If A then B; A is false; therefore B is false" — but B may hold for other reasons.

Structure

Special Pleading

Applying standards or rules to others while exempting yourself, without justifying the exception.

Structure

The Fallacy Fallacy

Concluding a claim is false just because an argument for it was fallacious. Bad arguments can defend true claims.

Structure