Logical Fallacies Cheat Sheet

The core ideas of Logical Fallacies distilled into a single, scannable reference — perfect for review or quick lookup.

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Quick Reference

Formal Fallacy

A formal fallacy is an error in the logical structure of an argument where the conclusion does not validly follow from the premises, regardless of the truth of those premises. These fallacies can be identified by examining the argument's form alone.

Informal Fallacy

An informal fallacy is an error in reasoning that arises from the content, context, or language of an argument rather than from its logical structure. These fallacies require understanding what the argument is about to identify the flaw.

Ad Hominem

An ad hominem fallacy attacks the person making an argument rather than addressing the argument itself. By targeting the speaker's character, motives, or background, the attacker tries to discredit the claim without engaging with its content.

Straw Man

A straw man fallacy occurs when someone misrepresents or oversimplifies another person's argument, then attacks that distorted version instead of the original claim. This creates the illusion of having refuted the opponent.

False Dichotomy

A false dichotomy, also called a false dilemma, presents only two options as if they are the only possibilities when other alternatives exist. This fallacy pressures the audience into choosing between extremes.

Appeal to Authority

An appeal to authority fallacy occurs when someone cites an authority figure as evidence for a claim, but the authority is not an expert in the relevant field, is biased, or their expertise alone is treated as conclusive proof.

Slippery Slope

A slippery slope fallacy argues that a single action will inevitably trigger a chain of increasingly extreme consequences, without providing evidence that each step in the chain is likely.

Hasty Generalization

A hasty generalization draws a broad conclusion from a small, unrepresentative, or insufficient sample of evidence. This fallacy ignores the need for adequate data before making sweeping claims.

Key Terms at a Glance

Logical Fallacy:An error in reasoning that renders an argument logically invalid or unsound, where the conclusion is not properly supported by the premises.

Formal Fallacy:An error in the logical structure or form of an argument, identifiable without examining the content of the premises.

Informal Fallacy:An error in reasoning related to the content, context, or language of an argument rather than its logical structure.

Ad Hominem:A fallacy that attacks the character or circumstances of the person making an argument rather than the argument itself. Latin for to the person.

Straw Man:A fallacy in which an opponent argument is misrepresented or distorted to make it easier to attack.

False Dichotomy:A fallacy that presents only two options as exhaustive when other possibilities exist. Also called a false dilemma.

Slippery Slope:A fallacy that argues one event will lead to a chain of increasingly extreme consequences without evidence that each step will occur.

Appeal to Authority:A fallacy that cites an authority figure as evidence when the authority lacks relevant expertise, is biased, or is cited without supporting evidence.

Red Herring:A fallacy that introduces an irrelevant topic to divert attention from the original subject of discussion.

Circular Reasoning:A fallacy in which the conclusion is assumed or restated in the premises, providing no independent support. Also called begging the question.

Hasty Generalization:A fallacy that draws a broad conclusion from an insufficient or unrepresentative sample of evidence.

Tu Quoque:A fallacy in which someone responds to criticism by pointing out that the critic does the same thing. A subtype of ad hominem. Latin for you too.

Fallacy Fallacy:The error of assuming that because an argument contains a fallacy, its conclusion must be false. Also called the argument from fallacy.

Non Sequitur:A conclusion that does not logically follow from the premises. Latin for it does not follow. A broad category encompassing many specific fallacies.

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