Logical Fallacies and Argument Tactics: A Guide with Examples

This guide covers selected common fallacies and argument tactics. It is not an exhaustive classification. Labels are a starting point; assess the premises, inference and context of each argument.

Formal and informal fallacies

A formal fallacy is an invalid pattern of deductive inference: the conclusion does not follow necessarily from the premises. For example: if A, then B; B; therefore A.

An informal fallacy concerns such matters as relevance, evidence, assumptions or the use of language in context. Finding one requires more than inspecting logical form. A formally valid argument may still beg the question or rely on false premises.

Validity means that true premises cannot lead to a false conclusion through that deductive form. Soundness requires both validity and true premises. For inductive arguments, assess the strength of the evidence rather than demanding deductive certainty.

Rhetorical devices and conversational labels are not automatically fallacies. The later section on argument tactics treats them separately. Naming a pattern does not establish that a particular argument is defective, nor does a defective argument prove its conclusion false.

Four groups used in this guide

The following groups are a practical way to navigate selected informal fallacies, not a complete or uniquely accepted taxonomy. Their boundaries overlap; some entries also describe conversational tactics.

Family 1: Fallacies of relevance

1. Ad hominem ("to the person")

Attacking the person making the argument rather than the argument itself.

Example: "You can't trust her economic analysis — she didn't even go to a top university."

Why it's fallacious: The validity of the economic analysis doesn't depend on where she studied. Her educational background is irrelevant to whether her arguments are sound.

When it's not a fallacy: When the person's character or credentials are actually relevant. If she's a self-proclaimed economist who has been caught fabricating credentials, that's relevant evidence about her reliability — not an ad hominem.

Deep dive: Ad Hominem, Straw Man, Slippery Slope: A Deep Dive.

2. Tu quoque ("you too")

A specific form of ad hominem: dismissing an argument because the arguer is guilty of the same thing.

Example: "How can you criticize my smoking? You smoked for ten years."

Why it's fallacious: The arguer's past behavior doesn't refute the argument. Smoking might still be bad even if the person warning against it once did it themselves.

Common modern form: "Whataboutism" — responding to criticism by pointing to similar behavior on the other side. ("How can the West criticize country X for human rights? They have problems too.")

3. Appeal to authority (argumentum ad verecundiam)

Citing an authority to support a claim outside that authority's expertise — or citing an authority when the claim is contested by experts in the relevant field.

Example: "Stephen Hawking believed in alien life. Therefore, aliens probably exist."

Why it's fallacious: Hawking was a physicist, not an exobiologist. His views on alien life carry no more weight than any educated person's.

When it's not a fallacy: Citing a genuine expert in the relevant field on a matter where experts agree is legitimate (often essential). "Climate scientists overwhelmingly conclude that anthropogenic climate change is real" is not a fallacy — it accurately reports scientific consensus.

4. Appeal to popularity (argumentum ad populum)

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

Example: "Most people think astrology has some truth to it. So there must be something to it."

Why it's fallacious: Popularity is not evidence. Many widely-held beliefs have been wrong (geocentrism, miasma theory of disease, witchcraft).

Bandwagon effect: A variant — appealing to growing popularity. "More and more people are switching to X..."

5. Appeal to emotion

Substituting emotional appeal for argument.

Subtypes:

• Ad misericordiam (appeal to pity): "You can't deny my asylum claim — think of my children."
• Ad baculum (appeal to force): "If you don't agree, you'll regret it."
• Ad metum (appeal to fear): "If the policy passes, our way of life will end."

Why it's fallacious: Emotion is real, but it doesn't validate or invalidate arguments. The asylum claim may be valid; the policy may be bad. Whether to support them requires reasons, not feelings.

When emotion is legitimate: Emotion as evidence about people's lives is legitimate. "Workers report feeling pressured" is data, not fallacy. Substituting emotion for argument is the fallacy.

6. Red herring

Introducing an irrelevant point to divert attention from the original argument.

Example: A: "We should reduce carbon emissions to combat climate change." B: "Why don't we focus on the real problem — illegal immigration?"

Why it's fallacious: Whether immigration is a problem is independent of whether climate change requires reducing emissions. B has changed the subject without addressing A's argument.

7. Straw man

Misrepresenting an opponent's argument to make it easier to refute.

Example: A: "We should regulate emissions from new cars." B: "So you want to ban driving?"

Why it's fallacious: A didn't argue for banning driving. B has attacked a position A didn't take.

Antidote — steel man: Reconstruct the opponent's argument in its strongest form before responding. If you can't refute the strongest version, you haven't refuted the argument.

Deep dive: Ad Hominem, Straw Man, Slippery Slope: A Deep Dive.

8. Genetic fallacy

Judging an argument by its origin rather than its content.

Example: "That idea came from Marx, so we can ignore it."

Why it's fallacious: An idea's source doesn't determine its validity. Marx had bad ideas and good ones. Each requires evaluation on its merits.

Family 2: Fallacies of weak induction

9. Hasty generalization

Drawing a broad conclusion from too few or unrepresentative examples.

Example: "I met two rude tourists from country X. People from country X are rude."

Why it's fallacious: Two examples is far too few. Even if both were representative (which we don't know), generalizing from two cases to an entire population is a category error.

10. Slippery slope

Arguing that one step will inevitably lead to a chain of negative consequences without justifying the chain.

Example: "If we allow gay marriage, next we'll allow polygamy, then we'll allow people to marry their pets."

Why it's fallacious: The chain of consequences isn't established. Each step needs argument; just asserting that they follow doesn't show that they do.

When it's not a fallacy: When the chain is established by empirical evidence or strong analytical reasoning. "If we allow zero-down mortgages, default rates will rise, which will pressure banks, which will tighten credit elsewhere" is not a fallacy if each step is supported.

Deep dive: Ad Hominem, Straw Man, Slippery Slope: A Deep Dive.

11. False dilemma (false dichotomy)

Presenting only two options when more exist.

Example: "Either you support our military intervention, or you're with the enemy."

Why it's fallacious: Other positions exist (oppose intervention but oppose the enemy too, support different intervention, etc.). The two presented options aren't exhaustive.

12. Appeal to ignorance (argumentum ad ignorantiam)

Arguing that something must be true because it hasn't been proven false (or vice versa).

Example: "Aliens must exist — no one has proven they don't."

Why it's fallacious: Absence of evidence is not evidence of absence (or presence). The burden of proof rests with the claimant; failure to disprove a claim doesn't establish it.

Caveat: In legal contexts (presumption of innocence) and scientific contexts (null hypothesis), there are legitimate reasons to default to one position absent evidence. These are not fallacies but procedural defaults.

13. Post hoc ergo propter hoc ("after this, therefore because of this")

Assuming that because B followed A, A caused B.

Example: "I started carrying a lucky charm and got the job. The charm worked."

Why it's fallacious: Sequence isn't causation. Many other things happened between getting the charm and getting the job; any could have been the cause.

14. Cum hoc ergo propter hoc ("with this, therefore because of this")

Assuming that because A and B are correlated, A causes B.

Example: "Cities with more police have more crime. Therefore police cause crime."

Why it's fallacious: Correlation doesn't establish direction or causation. More police could be a response to more crime; both could be caused by a third factor (population density).

This is the most-quoted statistical fallacy in popular science writing.

15. Texas sharpshooter fallacy

Drawing a circle around clustered events after the fact and claiming significance.

Example: A researcher tests 100 hypotheses; 5 produce statistically significant p-values. The researcher writes a paper about the 5, ignoring the 95.

Why it's fallacious: At the standard 5% significance threshold, you expect 5 of 100 hypotheses to appear significant by chance alone. Cherry-picking the apparent signals from noise produces false discoveries.

This is the foundation of "p-hacking" — a major source of replication crisis in scientific research.

Family 3: Fallacies of presumption

16. Begging the question (petitio principii)

Assuming the conclusion in the premise. The argument's premise depends on its conclusion.

Example: "The Bible is true because the Bible says it is true."

Why it's fallacious: This is circular. The premise (the Bible says it's true) only matters if we already accept the conclusion (the Bible is reliable). The argument doesn't establish anything.

Common modern form: "Begging the question" is also colloquially used to mean "raises the question." This is widespread but technically wrong — it confuses the philosophical term with a different meaning. We use it here in the philosophical sense.

17. Loaded question

Asking a question that contains an unjustified assumption.

Example: "Have you stopped beating your wife?"

Why it's fallacious: Both "yes" and "no" answers concede that the person was beating his wife. The question contains the assumption.

Modern forms: "When did you decide to oppose worker safety?" "Why does your party hate freedom?"

18. No true Scotsman

Defending a generalization by redefining the category to exclude counterexamples.

Example: A: "No Scotsman puts sugar in his porridge." B: "Angus McTavish puts sugar in his porridge, and he's a Scotsman." A: "Ah, but no true Scotsman puts sugar in his porridge."

Why it's fallacious: A is redefining "Scotsman" to exclude the counterexample, making the generalization unfalsifiable. The argument becomes circular.

Common modern form: Defending a movement by saying that anyone who behaves badly within it isn't a "real" member.

19. Special pleading

Claiming an exception to a general rule without justifying the exception.

Example: "Yes, in general it's wrong to break promises. But in my case, I had to break that promise because..."

Why it's fallacious: The exception requires justification. Exceptions to general rules can be valid (genuine emergencies, conflicting duties), but they need to be argued, not just claimed.

20. Moving the goalposts

Demanding more evidence after the originally requested evidence has been provided.

Example: A: "Show me one historical example of policy X working." B: "Here's one." A: "Show me three." B: "Here are three." A: "Well, those don't count because..."

Why it's fallacious: The standard of evidence keeps shifting. The arguer is changing the criteria mid-argument to avoid conceding.

Family 4: Fallacies of ambiguity

21. Equivocation

Using a word in two different senses within the same argument.

Example: "The sign said 'fine for parking here,' so I figured it was fine to park here."

Why it's fallacious: "Fine" means penalty in the sign and acceptable in the second sentence. The argument trades on the ambiguity.

Common modern forms: Using "natural" to mean both "from nature" and "morally good." Using "freedom" to mean both "absence of constraint" and "ability to do things."

22. Amphiboly

Ambiguous sentence structure that allows multiple interpretations.

Example: "Visiting relatives can be tiresome."

Why it's fallacious in argument: If used in an argument, the ambiguity allows the arguer to shift between meanings ("visiting your relatives" vs. "relatives who are visiting you") depending on what's convenient.

23. Composition

Inferring that what's true of the parts must be true of the whole.

Example: "Each player on the team is excellent. Therefore, the team is excellent."

Why it's fallacious: A team's quality depends on more than individual skill — coordination, role fit, chemistry. The whole has emergent properties not present in the parts.

24. Division

Inferring that what's true of the whole must be true of the parts.

Example: "Americans are obese. John is American. Therefore, John is obese."

Why it's fallacious: A statement about the population doesn't determine individual cases. Many Americans are not obese.

Argument tactics and conversational labels

The following entries describe tactics, evidence-handling practices and informal labels. They are not six additional, universally accepted categories of logical fallacy. Analyse what happens to the claim and its support in each case.

25. Motte and bailey

A speaker advances a strong claim, retreats to a weaker defensible claim when challenged, then resumes the strong claim without supporting it. For example: “All criticism is censorship” becomes “Some criticism intimidates people.” Defending the second claim does not establish the first. Distinguish this shift from openly revising a position.

26. Kafkatrap

A conversational label for treating denial of an accusation as evidence of guilt: “Your denial proves it.” The problem is the absence of an independent test of the accusation, not the mere use of a denial.

27. Galaxy-brained reasoning

An informal, often mocking label for an overly elaborate or counterintuitive explanation. It is not a standard category of logical fallacy. An unusual explanation can be correct; identify unsupported premises or inferences rather than dismissing it by this label.

28. Whataboutism

Responding to a criticism by pointing to someone else's conduct. It can distract from the original issue or function as tu quoque, but a relevant comparison may expose inconsistent standards. Ask whether the comparison answers the claim.

29. Cherry picking

Selecting favourable evidence while omitting relevant contrary evidence. This practice can weaken an inductive argument. For example, presenting only successful trials can misrepresent the overall results. Assess the full evidence and the selection rule.

30. Gish gallop

Presenting many claims faster than another person can assess them. This is a debate tactic, not proof that every claim is false. Separate the claims and ask for support for each.

How to spot fallacies in real arguments

Three practical tests:

Test 1 — Reconstruct the argument explicitly.

Pull the argument out of its rhetorical packaging. State the premises and conclusion in their simplest form. Many fallacies become obvious once stripped of emotional language and asides.

Test 2 — Check for missing premises.

Many fallacies hide in implicit premises that the argument assumes but doesn't state. Make implicit premises explicit; then evaluate them.

Test 3 — Steel-man the opposing view.

Before identifying fallacies in someone else's argument, ask: what is the strongest version of this argument? If you can refute the strongest version, you have refuted the position. If you can only refute the weakest version, you have committed straw man.

The limits of fallacy hunting

A warning that this guide must include: knowing fallacies doesn't make you immune to them, and using fallacy labels can become its own form of bad argument.

The fallacy fallacy: Assuming an argument's conclusion is false because the argument contains a fallacy. An argument can be flawed but reach a correct conclusion. Calling out fallacies establishes that the argument fails; it doesn't establish that the conclusion is false.

Fallacy labeling as dismissal: In contemporary discourse (especially online), naming fallacies has become a way to dismiss arguments without engaging with them. "Ad hominem!" is shouted at any criticism of a person, including legitimate criticism. "Straw man!" is shouted at any reformulation of an opponent's view, including charitable ones. The label substitutes for analysis.

The deeper question: A serious thinker doesn't ask only "what fallacy is this?" but "is the conclusion correct, and how can we tell?" Fallacy analysis is a tool for evaluating arguments, not a substitute for evaluating positions.

Sister pillar

For the closely related topic of cognitive biases — the systematic errors in human reasoning that produce flawed arguments — see: Cognitive Biases: The Complete List.