Logical Fallacies: The Complete Guide with 18 Examples

A logical fallacy is an error in reasoning — an argument that appears to be valid but contains a flaw that makes it invalid or significantly weaker than it appears. Recognizing fallacies is among the most practical skills that rhetorical and logical education can provide: once you can name and identify a fallacy, its apparent force evaporates.

This guide covers 18 of the most common and consequential logical fallacies, organized into three groups: fallacies of relevance (where the supporting argument is irrelevant to the claim), fallacies of evidence (where the evidence is mishandled), and fallacies of presumption (where hidden, unwarranted assumptions do most of the work).

A Critical Note

Naming a fallacy is not the same as refuting an argument. If someone accuses you of ad hominem when you have legitimately questioned a speaker's credibility as relevant to their claim, the accusation itself may be fallacious. Always ask: is the identified pattern actually a fallacy in this case, or does the argument have merit despite resembling a fallacy's form?

Fallacies of Relevance

These fallacies introduce considerations that are logically irrelevant to the truth or validity of the claim.

Ad Hominem

Attacking the person making the argument rather than the argument itself. The character of the speaker is irrelevant to the truth of the claim — unless the claim is specifically about their character or credibility.

"We shouldn't take her climate research seriously — she drives a large SUV."

Straw Man

Misrepresenting an opponent's argument in a weaker or more extreme form, then refuting the misrepresentation. One of the most common fallacies in political debate.

"My opponent wants to reduce the defense budget. Apparently she thinks we should have no military at all."

Appeal to Authority (Illegitimate)

Using the opinion of an authority as evidence in a domain where they lack relevant expertise. Note: legitimate appeals to genuine expertise are not fallacious.

"This famous athlete endorses this diet — it must work."

Appeal to Emotion

Manipulating emotions to substitute for a logical argument. Note: emotional appeals are legitimate when the emotion is appropriate and does not replace argument.

"Think of the children! How can you vote against this bill?" (when the bill's merits are never addressed)

Appeal to Popularity

Arguing that something is true or good because many people believe or do it. Popularity does not establish truth.

"Millions of people can't be wrong — this supplement must work."

Tu Quoque

"You too" — dismissing a criticism by pointing out that the critic is guilty of the same failing. Hypocrisy doesn't make a criticism false.

"You're telling me to exercise more? You haven't been to the gym in months."

Fallacies of Evidence

False Cause
(Post Hoc)

Assuming causation from correlation or temporal sequence. That B followed A does not mean A caused B.

"Crime rates dropped after the new police chief was appointed — he's clearly responsible."

Hasty Generalization

Drawing a general conclusion from an insufficient or unrepresentative sample.

"I've met three people from that city and they were all rude. Everyone from there must be like that."

Anecdotal Evidence

Using a personal story or isolated example as evidence against systematic data. The plural of anecdote is not data.

"My grandmother smoked until 90 — the lung cancer statistics must be exaggerated."

Cherry Picking

Selecting only the evidence that supports the desired conclusion while ignoring disconfirming evidence.

A drug company that publishes only the positive trials and suppresses the negative ones.

Burden of Proof Reversal

Claiming that because something has not been disproved, it must be true. The burden of proof lies with the positive claim, not with skeptics.

"You can't prove this supplement doesn't work, so it must be effective."

Fallacies of Presumption

False Dilemma

Presenting only two options when more exist. Also called the black-and-white fallacy or either/or fallacy.

"You're either with us or you're with the terrorists." — G.W. Bush, 2001

Slippery Slope

Claiming that one step will inevitably lead to extreme consequences without evidence of the causal chain. Not always fallacious — sometimes the chain is demonstrable.

"If we allow same-sex marriage, soon people will want to marry their pets."

Circular Reasoning
(Begging the Question)

Assuming the conclusion in the premises. The argument appears to provide evidence but actually just restates the claim in different words.

"The Bible is true because the Bible says so."

Appeal to Nature

Arguing that something is good because it is "natural" or bad because it is "unnatural." Natural/unnatural is not a reliable guide to beneficial/harmful.

"This supplement is completely natural — it must be safe."

No True Scotsman

Protecting a generalization from counter-examples by redefining the category to exclude them.

"No true socialist would support that policy." "But Politician X supports it and identifies as socialist." "Well, then X is no true socialist."

Genetic Fallacy

Evaluating a claim based on its origin rather than its merit. The source of an argument is irrelevant to whether the argument is correct.

"We can dismiss that study — it was funded by an advocacy group." (without examining whether the methodology was sound)

How to Respond to Fallacious Arguments

Identifying a fallacy in someone else's argument is one skill; responding to it effectively is another. A few principles:

Name it, explain it, and replace it. Simply shouting "that's a straw man!" rarely persuades. Explain why the representation is inaccurate, provide the accurate version, and engage that.
Distinguish the argument from the arguer. Even if someone is arguing in bad faith, their argument may deserve engagement on its merits.
Don't use fallacies to fight fallacies. Responding to a straw man with an ad hominem creates two fallacies where one existed. The goal is to improve the quality of the argument, not win at any cost.

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