The Hall of Fallacies

Every named way an argument fails — each one in plain words and in rigorous form. The interactive atlas lives at fallacy.tracksystem.us.

Accent Fallacy

also known as: accentus, fallacy of accent

Taking something someone said and leaning on a different word, or cutting the quote short, to make it sound like they said something else.

In the group chat, Dana texts: "I don't have a problem with Sam's plan, I have a problem with the deadline attached to it." A coworker screenshots only the first half and reads it back out loud in a flat, confident voice: "She said she doesn't have a problem with Sam's plan," stopping right before the comma and stressing it like a settled fact. Everyone in the room now thinks Dana signed off on the plan itself, when what she actually said was closer to the opposite.

The tell: Something feels off even though the exact words match what was said or written. You find yourself wanting to say "that's not how I said it" or "read the whole thing" — the words are technically real, but the tone or the cut-off point is doing work the original sentence never asked it to do.

The move: A statement S is uttered or written under one stress/emphasis/punctuation/quotation pattern with content C. The arguer restates S under a different stress, emphasis, or quotation boundary, producing apparent content C*, then treats C* as if it were what was actually said and draws a conclusion from C* rather than from C.

Why it fails: Stress, emphasis, punctuation, and quotation boundaries are load-bearing parts of meaning, not decoration. Changing them changes what proposition is on the table. The argument's conclusion is licensed only by C*, the re-accented or re-clipped version, but the premise on offer was actually C. Because C and C* are not the same claim, the inference silently substitutes a claim the original speaker never made for the one they did, which is an equivocation across two readings of one string of words rather than a move from evidence to conclusion.

Legitimate when: Re-emphasizing or re-punctuating a statement is legitimate when it faithfully reproduces the stress or context the original speaker actually intended or supplied themselves (for example, quoting someone's own italics, their own scare quotes, or a contrast they clearly drew), so that C* just is C rather than a rival reading manufactured by the arguer.

Ancient: Aristotle names accent (in Greek, prosody, later rendered in Latin as accentus) among the fallacies that depend on language. His illustration turns on a Greek word that reads one way and means 'where' but, given a different accent, reads as 'not' — since accent marks were not customarily written down in his day, a disputant could exploit the gap between the written word and its intended pronunciation to shift its sense. — Aristotle, On Sophistical Refutations

Built from: Wikipedia · Stanford Encyclopedia of Philosophy — Fallacies · The Fallacy Files — On Accent · Logically Fallacious — Accent Fallacy

Accident Fallacy

also known as: accidens, fallacia accidentis

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Ad Fidentia

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Ad Hoc Rescue

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Ad Hominem (Abusive)

also known as: argumentum ad hominem, abusive ad hominem

Instead of answering what you said, someone insults who you are and acts like that settles it.

In the group chat, Maria suggests splitting the dinner bill evenly since everyone ordered about the same. Dev replies, 'Ha, of course the person who showed up 20 minutes late thinks that's fair. Nobody's listening to you.' Nobody in the chat actually explains why splitting the bill evenly is unfair — Dev just makes fun of Maria being late and the group moves on as if her idea got shot down.

The tell: You notice the conversation never actually touched the idea itself — it went straight from 'here's my point' to 'here's what's wrong with you' — and somehow the point got treated as dead anyway, even though nobody laid a finger on it.

The move: Speaker S asserts claim P. S has unfavorable personal trait, history, or attribute T (unrelated to the truth-bearing content of P). Therefore, P is false / need not be considered.

Why it fails: T, whatever it is, is not evidence about the world that P describes. P's truth depends on how things stand outside of S — on facts, reasons, or data — not on S's character, habits, appearance, or past conduct. Swapping an evaluation of that external evidence for an evaluation of the speaker commits a relevance failure: the premise (the insult) and the conclusion (P is false) are not logically connected, even though the abuse can be psychologically effective at making an audience stop listening. The fallacy is compounded because the attack usually supplies no independent reason to doubt P at all — it substitutes for argument rather than supplementing it.

Legitimate when: Personal facts about a speaker are legitimately relevant when the question at issue is genuinely about the speaker — their credibility as a witness, their reliability as a testifier where independent verification is unavailable, a conflict of interest bearing on a recommendation, or their fitness for a role of trust. In a courtroom, impeaching a witness's character for truthfulness is procedurally proper because the jury must weigh testimony, not a free-standing factual claim submitted for its own evaluation. What is never legitimate is treating T as if it settled the truth of a separately verifiable proposition P.

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Ad hominem · Logically Fallacious — Ad Hominem (Abusive)

Ad Hominem (Circumstantial)

also known as: argumentum ad hominem, circumstantial ad hominem

The move: S has interest or circumstance C; ∴ S's claim P is false.

Why it fails: Possible bias is treated as refutation rather than a reason for scrutiny.

Legitimate when: Circumstances bear on credibility or undisclosed conflicts and are weighed proportionately.

Ad Hominem (Guilt by Association)

also known as: argumentum ad hominem, guilt by association

Making you dislike an idea just by pointing out that someone unlikeable also likes it — even though that has nothing to do with whether the idea is actually good.

In the group chat, someone shares a great budgeting app they've been using. Marcus replies, 'lol that's the app my ex used, and she was an absolute nightmare with money — hard pass.' Nobody has said one word about whether the app actually helps people save money. Marcus just took his leftover bad feelings about his ex and pasted them onto an app she happened to use too.

The tell: You notice the conversation quietly shifted from 'does this thing work' to 'who else likes this thing' — and somehow that swap felt like it settled something. A good gut check: imagine the exact same idea coming from someone likable instead. If the objection disappears, it was never about the idea.

The move: Person or claim X is linked to person/group G (X endorses G, is endorsed by G, resembles G, shares a category with G, or is merely near G). G has an unfavorable property or reputation. Therefore, X — or X's specific claim — is discredited, without any further premise showing that the link actually transmits G's fault to X or to X's claim.

Why it fails: The argument treats shared membership in a group, or mere proximity to a disliked party, as if it were evidence about the truth or merit of a separate, specific claim. But an association is not automatically a channel through which a trait travels: it can be incidental, involuntary, partial, or entirely unrelated to the content of the claim at issue. Even when the association is real and voluntary, the disliked party's endorsement adds no new evidence about the world the claim describes — a true claim stays true and a bad plan stays bad regardless of who else likes it. The fallacy substitutes an evaluation of the company a claim keeps for an evaluation of the claim itself, which is a relevance failure: the premise (the association) and the conclusion (the claim is false or the person is bad) are not logically connected, only emotionally connected via transferred disapproval.

Legitimate when: The association is legitimate evidence when it reveals a genuine, direct, and relevant link between the disliked party and the specific claim — for example, the person actively adopted and now promotes the group's particular reasoning, took material support from them in exchange for advocacy, or the shared trait is precisely the one in dispute (e.g., a group's demonstrated pattern of fraud is relevant when evaluating whether to trust its new financial pitch). In such cases the move shades into a legitimate circumstantial ad hominem — it gives a reason to scrutinize possible bias or motive, but even then it only justifies added scrutiny, not outright dismissal of the claim on its own terms.

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Association fallacy · Internet Encyclopedia of Philosophy — Fallacies · Logically Fallacious — Ad Hominem (Guilt by Association) · The Fallacy Files — Guilt by Association

Ad Hominem (Tu quoque)

also known as: argumentum ad hominem, tu quoque, you too

Dodging criticism by pointing out the critic is a hypocrite, instead of answering what they actually said.

In the group chat, Priya posts: 'We really should stop ordering so much takeout, it's wrecking the budget.' Marcus fires back: 'You ordered pad thai literally last night, so I'm going to go ahead and ignore this.' Nobody in the chat actually addresses whether cutting takeout would help the budget — Marcus just made Priya's hypocrisy the whole topic, and the group moves on like the budget point got answered.

The tell: Notice that the actual point never got touched. Someone brought up a fact about the *person* talking instead of the *thing* they said, and somehow that felt like enough to end the conversation.

The move: Speaker S asserts claim X (often a norm, warning, or recommendation). Listener L observes that S's own conduct is inconsistent with X — S does not practice what X calls for. L concludes: therefore X is false, or S's case for X may be dismissed.

Why it fails: The truth of X depends on the world, not on the biography of whoever states it. A hypocrite's inconsistency is evidence about the hypocrite's character or sincerity, but it supplies no evidence bearing on whether X itself is true. Treating 'S fails to live up to X' as if it settles 'X is false' swaps a question about the speaker for the question actually on the table, so the criticism of X stands or falls untouched by anything just said about S.

Legitimate when: Pointing out inconsistency is not always fallacious. It is legitimate when the inconsistency bears on the speaker's sincerity, credibility as a witness, or standing to demand compliance from others (compare the equitable 'clean hands' doctrine, which withholds a remedy from an inconsistent party without pretending the underlying legal rule is false). It is also legitimate, following Locke's original sense, when used to expose that an opponent's own stated principles already commit them to a conclusion they are resisting — that is argument from the opponent's premises, not a claim that those premises are false because of who holds them.

Ancient: Jesus anticipates that his hearers will throw the proverb 'Physician, heal thyself' back at him — deflecting his message by pointing to his own condition rather than answering what he actually said. It is one of the oldest widely cited instances of the pattern, though the proverb is not presented there as a named fallacy, and the passage's original point was about expected miracles rather than a formal logic lesson. — Gospel of Luke 4:23 (quoting an older proverb)

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Tu quoque · Internet Encyclopedia of Philosophy — Fallacies

Affirmative Conclusion from a Negative Premise

The move: At least one negative categorical premise; ∴ an affirmative conclusion.

Why it fails: A premise asserting separation cannot by itself establish the positive inclusion claimed.

Legitimate when: In standard categorical logic, a negative premise requires a negative conclusion.

Affirming a Disjunct

The move: P ∨ Q; P; ∴ ¬Q

Why it fails: Ordinary logical disjunction is inclusive, so P and Q may both be true.

Legitimate when: Valid with exclusive-or, not inclusive-or.

Affirming the Consequent

Just because the thing you expected to see showed up doesn't mean your favorite explanation is what caused it.

In the group chat, Mia types: "If Jordan won the raffle, he'd be posting a victory selfie right about now. He just posted a victory selfie. So Jordan won the raffle!" Except Jordan posts a victory selfie practically every other day — for free pizza, for a good parking spot, for finishing a crossword before his coffee got cold. The selfie showing up doesn't prove anything about the raffle specifically; it just proves Jordan likes posting selfies.

The tell: You get a nagging feeling that the explanation clicked a little too fast — like one single clue got used to lock in one single story, when that exact same clue would fit a dozen other stories just as comfortably.

The move: If P then Q; Q is true; therefore P is true. (P → Q, Q, ∴ P)

Why it fails: The conditional "if P then Q" only asserts that P is sufficient to produce Q — it says nothing about whether P is the only thing that can produce Q. Affirming Q and concluding P treats the one-way conditional as though it were reversible (as though P ↔ Q), which the original statement never established. Q can be true for reasons that have nothing to do with P, so its truth gives no reliable evidence that P occurred.

Legitimate when: The move is legitimate only when the converse (Q → P) has been independently established — i.e., when P and Q are genuinely equivalent (P if and only if Q), so that Q really does uniquely point back to P and nothing else could have produced it.

Ancient: Aristotle observes that people slide from "if A is true, B is necessarily true" into wrongly believing "if B is true, A is necessarily true" as well. His example: because a person with a fever is hot, people wrongly infer that anyone who is hot must have a fever — even though heat can just as easily come from exercise, sunshine, or a warm room, not only from fever. — Aristotle, On Sophistical Refutations, ch. 5 (169b19)

Built from: Wikipedia · Stanford Encyclopedia of Philosophy — Fallacies · Internet Encyclopedia of Philosophy — Fallacies

Alleged Certainty

Why it fails: A disputed assumption, burden, category boundary, or conclusion is smuggled into the premises or procedure.

Legitimate when: The presupposition is established independently or stipulated by all parties.

Alphabet Soup

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Alternative Advance

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Amazing Familiarity

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Ambiguity Fallacy

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Anonymous Authority

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Anthropomorphism

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Appeal to Accomplishment

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Anger

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Authority

also known as: argumentum ad verecundiam, appeal to modesty

Believing something just because an impressive-sounding person said it, without checking whether that person actually knows this particular thing.

In the family group chat, someone posts a screenshot: 'My dentist said this new detox tea flushes out toxins and boosts your immune system, and she's literally a doctor, so I'm ordering a case.' Nobody asks what a dentist knows about immune systems or detox drinks; the word 'doctor' does all the work, and three cousins immediately ask for the link.

The tell: You notice the conversation has stopped being about proof and started being about who said it — nobody can point to a study, a test, or a real result, they can only point to the person's title or fame, and somehow that feels like enough.

The move: Authority S asserts that P. S is (treated as) an authority. Therefore, P.

Why it fails: The move is only as good as the unstated bridge premises it skips: that S is actually an expert in the specific domain P falls under, that S is representing the real state of expert opinion rather than a fringe or superseded view, that S is not compromised by bias or conflict of interest, and that S's words are being accurately reported rather than distorted or stripped of qualification. When any of those conditions is missing, the argument substitutes the fact of an assertion for evidence for the assertion — it treats testimony about who believes P as if it were evidence for P itself. The Stanford Encyclopedia of Philosophy frames the core failure as accepting a pronouncement 'as evidence for a proposition' from someone 'taken to be an authority but [who] is either not really an authority or a relevant authority' — the defect is a relevance failure, not a rejection of expertise as such.

Legitimate when: Deferring to a genuine, domain-relevant, disinterested authority is a reasonable and often necessary shortcut when independently verifying every claim is impractical — this is defeasible reliance: it holds provisionally, is revisable in light of better evidence or a more qualified authority, and is strongest when the expert's claim falls within a field with real, checkable methods and a working consensus (e.g., citing a virologist on how a specific virus spreads).

Ancient: Cicero describes how Pythagoras's followers, when challenged to defend a claim in debate, would simply answer 'ipse dixit' — 'he himself said it' — letting the master's bare word close off further argument instead of offering reasons of their own. — Cicero, De Natura Deorum, Book I

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Argument from authority · Wikipedia — Ipse dixit

Appeal to Celebrity

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Closure

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Coincidence

Why it fails: The evidence does not identify the claimed causal direction, mechanism, or counterfactual contrast.

Legitimate when: A credible experiment, quasi-experiment, mechanism, or identification strategy supplies the missing link.

Appeal to Common Belief

also known as: argumentum ad populum, appeal to belief

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Common Folk

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Common Sense

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Complexity

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Consequences

also known as: argumentum ad consequentiam

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Definition

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Appeal to Desperation

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Emotion

Someone makes you feel something strong on purpose, then hopes that feeling will do the arguing for them instead of any actual reason.

A friend group chat is deciding where to eat. One person doesn't want the vote to go to the new salad place, so instead of saying why, they type: 'Wow, guess nobody cares that I've had the worst week of my life and just wanted one nice comfort meal with people who love me.' Nobody answers the actual question of where to eat. Everyone just scrambles to comfort them, and the group ends up at the comfort-food spot.

The tell: You notice the conversation has stopped being about the actual question and has turned into managing someone's mood, guilt, or fear. You feel a tug to agree just to make the bad feeling stop, even though you couldn't explain, in plain words, what reason you were just given.

The move: An emotion E (fear, pity, anger, joy, outrage, sympathy, etc.) is aroused in the audience by some description, image, or appeal; the intensity of the felt E is then substituted for evidence that claim P is true or that action A should be taken; therefore P / therefore A. The emotional charge, not any fact connecting E to P, is what does the persuasive work.

Why it fails: The strength of a feeling is not itself evidence for the truth of a proposition. When the arousing detail has no probative connection to the matter actually at issue, the argument commits a relevance failure (a red herring): it offers a psychological cause of belief in place of a reason to believe. An audience can feel the aroused emotion just as strongly whether P is true or false, so the emotion tracks nothing about P's truth-value; it only tracks how the material was presented.

Legitimate when: Emotion-evoking facts are not automatically illegitimate: an emotion is properly probative when the very thing that makes it distressing, pitiable, or alarming is also a genuine reason bearing on the decision at hand (e.g., a victim-impact statement describing real harm is relevant to a sentencing decision; a vivid but accurate description of a risk is relevant to a safety decision). The move becomes fallacious specifically when the emotional charge is doing work that no accompanying fact could do on its own, or when it is used to override, distract from, or substitute for evidence that would otherwise settle the question.

Ancient: Aristotle criticizes earlier handbook writers for teaching speakers how to arouse a judge's prejudice, pity, or anger rather than sticking to the facts of the case, comparing the tactic to warping the measuring-stick before you use it to measure — even as his own Rhetoric goes on to give a systematic account of how the emotions work, on the view that a speaker should understand them well enough to know when they are legitimately in play. — Aristotle, Rhetoric

Built from: Wikipedia · Stanford Encyclopedia of Philosophy · Internet Encyclopedia of Philosophy

Appeal to Equality

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Extremes

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Faith

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to False Authority

also known as: argumentum ad verecundiam, false authority

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Fear

Someone tries to scare you into agreeing instead of actually giving you a reason.

You're buying a laptop and you tell the salesperson you'll skip the extended warranty. He leans in and says, 'Your call, but hard drives fail all the time. Picture it: every photo of your kids growing up, gone, no warning, right when you need it least.' He never mentions how often this laptop's drives actually fail, what the warranty even covers, or what it costs to just back up your files yourself for five dollars a month. He just needs you to picture the empty photo album.

The tell: The conversation stops being about facts and starts being about a scary picture in your head. You feel a jolt of dread, but if someone asked you to explain out loud exactly why saying no would actually cause the bad thing, you'd realize you can't.

The move: A frightening outcome F is presented as what will happen if claim P is rejected or action A is not taken; the vividness and imminence of F, rather than any demonstrated causal or evidential link between rejecting P and F occurring, is what carries the audience to the conclusion. Schematically: 'If not-P, then (frighteningly) F; F must be avoided; therefore P.' Often paired with a false dilemma that hides every option except the frightening one and the arguer's preferred one.

Why it fails: Being afraid of F is not evidence that rejecting P causes F, or that P is true. The argument needs two things it never supplies: that F is actually likely to follow from not-P, and that the magnitude of F (as opposed to just its emotional charge) has been honestly weighed against the cost of accepting P. When the frightening image substitutes for that missing causal and probabilistic case, the audience is moved by dread rather than by any reason connecting the two claims — the fear is doing persuasive work that only evidence should do.

Legitimate when: Warning someone of a real, evidenced risk is not fallacious just because it is frightening — a doctor describing a surgery's documented complication rate, a structural engineer flagging a cracked support beam, or a weather service issuing an evacuation order are all appealing to genuine, quantified danger as one relevant factor among others. The move turns fallacious specifically when the fear is the only thing doing the persuading, the causal link to the rejected claim is asserted rather than shown, and the probability of the outcome is left vague on purpose because a clear number would weaken the pitch.

Ancient: Aristotle analyzes fear (phobos) as pain or disturbance arising from the impression that some destructive or painful evil is close at hand, and explains that a speaker can make an audience feel this by making the danger seem near and the audience seem vulnerable to it. His treatment is descriptive rather than a condemnation — he is cataloguing how the emotion works so a speaker can understand and use it — but it is the ancient source later fallacy theorists point to when they identify fear as a lever an arguer can pull independent of the actual merits of a case. — Aristotle, Rhetoric, Book II

Built from: Wikipedia · Stanford Encyclopedia of Philosophy · Logically Fallacious

Appeal to Flattery

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Force

also known as: argumentum ad baculum, appeal to the stick

Someone gets you to agree not because they're right, but because they can hurt you if you don't.

You tell your roommate the cleaning schedule they wrote up isn't fair because it has you doing dishes every single night. Instead of explaining why the schedule makes sense, they say, 'Fine, keep arguing about it, and see if I don't tell the landlord it was your idea to sneak in a second cat.' Nothing about that response tells you the schedule is actually fair. It just tells you what happens if you keep pushing.

The tell: You notice the conversation has quietly stopped being about who's right and started being about what you stand to lose. The other person hasn't answered your point at all, they've just made it more expensive to keep making it.

The move: The arguer holds (or claims to hold) the power to inflict some harm T on the audience, and presents acceptance of claim P as the only way to avoid T: 'Accept P, or I will do T to you; therefore P.' The threatened harm is offered in the place a reason for P's truth should occupy, and the harm's source is the speaker's own will, not an independent fact about the world.

Why it fails: A threat can give someone a genuine reason to act a certain way, but it cannot give anyone a reason to believe a certain way. Whether P is true or false does not change depending on who is willing to hurt you over it, so a threat directed at belief supplies zero evidential weight for P — it only changes the cost of disagreeing. The fallacy specifically targets doxastic appeals ('believe P or else') rather than practical ones ('do X or else'), and it is aggravated when the harm is one the speaker themselves will inflict, since that removes even the indirect informational value a third-party warning might carry.

Legitimate when: Consequences are legitimate reasons in practical deliberation: a union that says 'settle fairly or we strike,' a nation that says 'withdraw or we cut off trade,' or an employer who says 'wear the hard hat, it's state law and the job requires it' are all pointing to real stakes that bear directly on what someone should decide to do. It only becomes the fallacy when the same threat is redirected at belief itself — 'accept that X is true, or else' — or when the stated 'reason' is nothing but the threat with no independent justification attached.

Ancient: The Athenian envoys tell the Melians that questions of justice arise only between equals in power, and that the strong do what they can while the weak suffer what they must — pressing Melos to submit on the basis of Athenian military strength rather than on the merits of Melos's claim to neutrality. — Thucydides, History of the Peloponnesian War, Book V (the Melian Dialogue)

Built from: Stanford Encyclopedia of Philosophy · Wikipedia · Logically Fallacious

Appeal to Heaven

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Intuition

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Loyalty

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Nature

also known as: argumentum ad naturam

Something isn't automatically good just because it's 'natural' — and it isn't automatically bad just because it's man-made.

In the group chat, a friend shares a supplement she's hyped about: 'It's literally just herbs, nothing synthetic in it — how could that possibly be bad for you?' Nobody in the thread asks what the herbs actually do once they're in your body, or mentions that nightshade and foxglove are also 'just herbs' and can stop your heart. The word 'natural' on the label is doing every bit of the convincing, and none of the actual work.

The tell: You realize the person has told you nothing about whether the thing actually works or is safe — only that it's 'natural,' as if that one word closes the case. Try naming a natural thing everyone agrees is dangerous (a hurricane, poison ivy) and watch the argument suddenly need a lot more support than it had a second ago.

The move: N is natural (or: N is unnatural). Therefore N is good/right (or: N is bad/wrong) — with an unstated bridging premise, never independently defended, that naturalness itself confers moral or practical merit (and its lack removes it).

Why it fails: The move fails on two fronts at once. First, 'natural' is descriptively slippery — it can mean 'occurs without human intervention,' 'found in the wild,' 'consistent with evolved human physiology,' or simply 'not synthesized in a lab,' and arguers switch between senses as convenient. Second, even once a sense is fixed, the step from 'is natural' to 'is good' is a non sequitur: arsenic, malaria, hemlock, and hurricanes are all thoroughly natural and bad for you, while vaccines, eyeglasses, antibiotics, and open-heart surgery are all artificial and good for you. Naturalness tracks no reliable correlation with safety, health, or moral worth on its own, so citing it supplies no actual reason for the conclusion — the premise and conclusion are related only by the positive connotation the word 'natural' carries, not by any evidence.

Legitimate when: When 'natural' is functioning as an evidentially earned shorthand rather than doing the justificatory work itself — e.g., a specific class of natural substances has an established track record (long clinical use, known mechanism, tested safety profile) that a specific synthetic alternative lacks, and the arguer is really pointing to that track record. The move becomes fallacious the moment naturalness is treated as sufficient on its own, in place of the evidence it happens to stand in for.

Ancient: Callicles contrasts nature (physis) with human convention (nomos) and argues that nature itself shows the stronger are meant to rule and take more than the weak, treating what he takes nature to display as settling what is truly just — a claim Socrates then presses and undermines through examination. — Plato, Gorgias (the speeches of Callicles)

Built from: Wikipedia — Appeal to nature · Wikipedia — List of fallacies · Stanford Encyclopedia of Philosophy — Fallacies · Logically Fallacious — Appeal to Nature · The Fallacy Files — Appeal to Nature

Appeal to Normality

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Novelty

also known as: argumentum ad novitatem

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Pity

also known as: argumentum ad misericordiam, appeal to mercy

Trying to win an argument by making people feel sorry for you instead of actually answering the question they asked.

In the group chat for splitting a camping trip's costs, Jordan owes $140 because the gear left in Jordan's tent got ruined in the rain. When someone brings it up, Jordan writes: 'You guys know my dog died last week, right? I really don't need this right now.' The chat goes quiet. Nobody mentions the $140 again - even though whether the dog died has nothing to do with whether Jordan was supposed to keep the gear dry.

The tell: You notice the conversation never actually answered your question - it just made you feel bad for having asked it. The subject quietly slid from 'did this happen' to 'how could you bring this up.'

The move: Rejecting claim P (or refusing action A) would cause sympathy-evoking hardship to someone; therefore P is true, or A is owed/required.

Why it fails: Hardship and sympathy are evidence about how bad an outcome feels, not evidence about whether P is true or about whether the standard governing A has been met. The argument quietly swaps the question that is actually in dispute (did the accounts reconcile, is the defendant guilty, was the work done) for a different question (how much does this person's suffering move me), and answers that second question instead. The relevance gap is the defect: nothing about the hardship bears on the disputed fact or on the criteria the decision is supposed to track.

Legitimate when: When the governing norm itself makes hardship, need, or mercy a legitimate factor in the decision - equitable sentencing discretion, need-based aid, humanitarian parole, a landlord choosing whether to show any leniency at all. It fails specifically when the standard in question is a factual or eligibility question (did the numbers add up, was the shot made, is the claim true) that suffering cannot answer, no matter how real that suffering is.

Ancient: Socrates observes that defendants on trial customarily bring forward their weeping children and relatives to move the jury to pity, and he declines to do so himself, arguing that a juror's oath is to judge according to law and the facts of the case, not to hand down favors to whoever seems most pitiable. — Plato, Apology

Built from: Wikipedia · Internet Encyclopedia of Philosophy - Fallacies · Stanford Encyclopedia of Philosophy - Fallacies

Appeal to Popularity

also known as: argumentum ad populum, bandwagon fallacy

A lot of people believing something doesn't make it true.

In the family group chat, someone shares a link and types, 'This detox tea has 40,000 five-star reviews, everyone's doing it, it obviously works.' Within an hour, three relatives have added it to their cart — nobody has asked what's actually in it or whether any of those 40,000 reviewers checked their blood work before and after.

The tell: You notice the person never actually explains why the thing is true or good — they just keep pointing at how many other people are already doing it, as if the headcount itself were the proof.

The move: A large number of people P believe X (or do X, or approve of X). Therefore X is true, correct, or ought to be done.

Why it fails: The size of the group holding a belief is offered as if it were evidence for the belief, but the premise (how many people hold X) and the conclusion (whether X is true) are logically independent: a belief's popularity is a fact about the psychology and sociology of a population, not a fact that was produced by, or tracks, whatever method would actually verify X. Unless the crowd's agreement was itself formed by a reliable, independent process, the number of people involved has no bearing on the truth of what they agree on, so citing that number does not raise its probability of being true.

Legitimate when: The move is legitimate in two situations: (1) when the claim under dispute is itself about the population's behavior, belief, or usage rather than about an external fact — e.g. what counts as correct grammar is set by how competent speakers actually use the language, so appealing to common usage is not fallacious but simply citing the relevant standard; and (2) when the aggregated judgment of many independent, reasonably competent assessors is a statistically reliable estimator of a shared answer (the Condorcet-style condition), so long as each person's belief was formed with some independence from the others rather than by copying the crowd.

Ancient: Socrates argues that on questions of how to live one should follow the judgment of the one who knows rather than the opinion of the many, as an athlete heeds his trainer rather than the crowd, since the many's approval does not track truth and the many 'can only do things haphazardly.' — Plato, Crito

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Argumentum ad populum · Internet Encyclopedia of Philosophy — Fallacies

Appeal to Possibility

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Ridicule

also known as: appeal to mockery, reductio ad ridiculum

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Self-evident Truth

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Spite

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Stupidity

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to the Law

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to the Moon

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Appeal to Tradition

also known as: argumentum ad antiquitatem, appeal to antiquity

Something being old, or 'the way we've always done it,' doesn't make it right.

At Thanksgiving, someone cuts the ends off the ham before baking it. Asked why, she says, 'Because my mother always did it that way, and so did her mother.' Someone finally calls grandma, who laughs: 'Oh, my pan was too small for a whole ham — that's the only reason.' Three generations followed a rule that was never about taste at all.

The tell: The only reason anyone gives is 'that's how it's always been' — nobody can say what the practice actually accomplishes, and if you ask 'but why does doing it that way actually help?' the conversation stalls.

The move: Practice, belief, or institution X has persisted since a past time T (or 'we have always done X' / 'the ancestors held X'). Therefore X is true, correct, or ought to continue.

Why it fails: The premise reports only that X has survived — that it was adopted at some point and has not been discarded since. Survival is a fact about a practice's history, transmission, and social inertia; it is not, by itself, a fact about whether X was ever tested against alternatives, still serves the purpose it once served, or is true. Something can persist purely because no one challenged it, because changing it was costly, or because the conditions that once justified it have long since disappeared. Unless the age of X is accompanied by independent evidence that it was selected for and has continued to satisfy some genuine standard, its longevity does not raise the probability that it is true or good, so citing that longevity alone does not support the conclusion.

Legitimate when: Long, unbroken survival can be legitimate evidence, not of truth, but of practical workability, when a practice has been in continuous use under conditions similar to today's and would plausibly have been abandoned or reformed had it repeatedly failed — a Burkean 'survivorship' inference, which is weak inductive evidence about function, not proof about truth or morality, and only holds while circumstances remain relevantly unchanged. It is also not fallacious when the thing actually in dispute is the tradition or custom itself (e.g., what counts as correct etiquette, or what a community's own rule has always been) rather than an external fact the tradition is being used to settle; and purely victimless customs kept for their own sentimental or cultural value need no further justification than being cherished.

Ancient: Roman political speech routinely treated the mos maiorum — the 'way of the ancestors' — as a standard to invoke on its own authority. In his Catilinarian orations, Cicero defended taking severe action against the conspirators partly by citing earlier instances of the Senate acting forcefully against threats, framing the measures as continuous with ancestral custom rather than as unconstitutional novelty — using the practice's ancestral pedigree itself as a reason to accept it. — Cicero and Roman oratory generally (the mos maiorum)

Built from: Wikipedia — Appeal to tradition · Wikipedia — List of fallacies · Logically Fallacious — Appeal to Tradition · Internet Encyclopedia of Philosophy — Fallacies

Appeal to Trust

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Argument by Emotive Language

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument by Fast Talking

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument by Gibberish

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument by Personal Charm

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument by Pigheadedness

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument by Repetition

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument by Selective Reading

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument from Age

also known as: argumentum ad antiquitatem

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument from Fallacy

also known as: argumentum ad logicam, fallacy fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument from False Authority

also known as: argumentum ad verecundiam

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument from Hearsay

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument from Ignorance

also known as: argumentum ad ignorantiam, appeal to ignorance

The move: P has not been disproved; ∴ P, or P has not been proved; ∴ ¬P.

Why it fails: Absence of proof is treated as proof of absence or presence without an expectation of detection.

Legitimate when: A well-powered search would probably detect the phenomenon if present.

Argument from Incredulity

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument from Silence

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument of the Beard

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Argument to Moderation

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Argument to the Purse

also known as: argumentum ad crumenam, appeal to wealth

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Arguments

Why it fails: This record is an index or methodological item rather than a substantive fallacy.

Legitimate when: Not applicable.

Avoiding the Issue

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Base Rate Fallacy

also known as: base rate neglect

The move: Posterior judgment relies on case evidence while neglecting prior prevalence.

Why it fails: Bayesian updating requires both likelihood and base rate.

Legitimate when: The base rate is irrelevant, already incorporated, or overwhelmed by a sufficiently strong likelihood ratio.

Begging the Question

also known as: petitio principii, assuming the conclusion

It tries to prove something true by just saying the same thing again in different words, as if that counted as a reason.

In the group chat, someone posts: "This is hands-down the best taco place in the city." A friend asks, "How do you know?" The reply: "Because it's obviously the top spot for tacos around here." Nobody actually said anything new — "best taco place" and "top spot for tacos" are the same claim, just reworded, so the question "how do you know" never actually got answered.

The tell: You notice you can't repeat the reason back in your own words without it turning into the exact same claim you were questioning. It feels like the conversation went in a circle and you ended up back where you started, no closer to being convinced.

The move: A conclusion C is defended by a premise P, but P is not independent support for C — either P and C are the same claim in different wording, or accepting P already requires having accepted C. The chain of support therefore runs from C back to C rather than from external grounds to C.

Why it fails: A proof is supposed to give a doubter of C a reason to accept C that does not itself depend on already accepting C. Here it cannot: anyone who denies the conclusion has exactly the same reason to deny the premise, since the premise just is the conclusion wearing different words (or is answerable only by presupposing the conclusion). The argument may even be formally valid — C does follow from P — but it makes no epistemic progress, because the 'support' is not independent of what it is supposed to support. Stanford Encyclopedia of Philosophy notes this is why the defect is best classed as epistemic rather than strictly logical: the argument's weakness lies in what counts as a reason, not in whether the conclusion follows.

Legitimate when: Circularity is legitimate when it functions as coherence-building rather than as proof to a doubter — e.g., a dictionary's large web of terms that mutually define one another, or a scientific theory whose parts mutually support each other within an already-accepted framework. Internet Encyclopedia of Philosophy makes this distinction explicit: a small, tight circle (A because B, B because A) is fallacious, but a large circle spanning many independent claims can be informative and is not treated as fallacious, because it is not being used to force assent from someone who rejects the whole system. It is also legitimate to state something as a premise and its logical restatement as a working definition, so long as no one is being asked to treat the restatement as newly-won proof.

Ancient: Aristotle treats 'asking for the original point' (petitio principii) as a standing flaw of dialectical argument: in a debate the answerer must not be made to grant, even in disguised wording, the very thesis that the argument was supposed to establish, since doing so lets the arguer 'obtain' the conclusion rather than prove it. — Aristotle, Topics and Prior Analytics (with parallel treatment in On Sophistical Refutations)

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Begging the question · Internet Encyclopedia of Philosophy — Fallacies

Biased Sample Fallacy

The move: Observed sample frequency is projected to a population despite selection bias.

Why it fails: Inclusion in the sample is correlated with the measured outcome.

Legitimate when: Selection is random or appropriately corrected.

Blind Authority Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Broken Window Fallacy

also known as: broken window parable

Why it fails: The evidence does not identify the claimed causal direction, mechanism, or counterfactual contrast.

Legitimate when: A credible experiment, quasi-experiment, mechanism, or identification strategy supplies the missing link.

Bulverism

also known as: psychogenetic dismissal

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Causal Reductionism

Why it fails: The evidence does not identify the claimed causal direction, mechanism, or counterfactual contrast.

Legitimate when: A credible experiment, quasi-experiment, mechanism, or identification strategy supplies the missing link.

Cherry Picking

also known as: suppressed evidence, fallacy of incomplete evidence

Showing only the wins and hiding the losses so the record looks better than it really is.

A boutique gym posts a carousel: three clients, dramatic 8-week transformations, huge smiles. What the post doesn't say: forty-two other people started that same 8-week program. Thirty saw no visible change, nine quit early, three actually gained weight. The three photos are real. The picture they paint is not.

The tell: You notice the person only ever shows success stories, never a single case that went badly, and when you ask 'okay, but what about the people it didn't work for,' they get vague or change the subject.

The move: From evidence set E = {e₁, e₂, ..., eₙ}, arguer presents only the subset Eₛ ⊂ E whose members support claim P, while relevant members of E \ Eₛ that weaken or contradict P are available, known (or knowable) to the arguer, and withheld. The audience is invited to treat Eₛ as if it were representative of E.

Why it fails: The defect is not in any single cited fact — each cherry-picked data point can be entirely true. The defect is that the selection rule used to build the evidence set was chosen because of its outcome (it agrees with P), not because of any independent criterion of relevance or quality. This breaks the link between 'the evidence I was shown' and 'the evidence that exists,' so the sample can no longer license a general or comparative claim about the whole body of evidence. It is a species of weak induction: the inference from Eₛ to P is only as strong as Eₛ is representative of E, and a motivated selection rule guarantees it isn't.

Legitimate when: Selecting a subset of evidence is legitimate — not fallacious — when the selection criterion is relevance- or quality-based, is fixed independently of whether it helps or hurts the arguer's position, and is disclosed. A meta-analysis that excludes studies for a stated, outcome-blind methodological flaw; a lawyer citing only the controlling precedent because non-controlling cases are legally irrelevant; a doctor ordering the specific tests indicated by a patient's symptoms rather than every test that exists — none of these is cherry picking, because the filter is applied the same way regardless of which result it would produce.

Ancient: Shown to a wall of votive paintings at a temple on Samothrace, each depicting a sailor who prayed to the gods and survived a shipwreck, a friend asked Diagoras — known as 'the Atheist' — whether the pictures didn't prove the gods answer prayer. Diagoras replied that of course they did, since nowhere were there any paintings of the sailors who prayed just as hard and drowned anyway. — Cicero, De Natura Deorum, Book III (via the character Cotta, recounting an anecdote about Diagoras of Melos)

Built from: Wikipedia — Cherry picking · Wikipedia — List of fallacies · Internet Encyclopedia of Philosophy — Fallacies · Logically Fallacious — Cherry Picking

Circular Definition

Explaining a word by using the word itself (or a twin of it), so you end up exactly where you started.

In a group chat about diets, someone asks, 'wait, what actually counts as a "clean" food?' A friend replies, 'easy — clean food is just food that isn't dirty. And dirty food is whatever isn't clean.' A few people react with a thumbs up like that settled it. But nobody in the chat is any closer to knowing whether the granola bar in their hand counts as clean or not.

The tell: The explanation sounds finished and confident, and your brain relaxes because a definition-shaped sentence got said. But the moment you try to actually use it — to decide one real case, like the granola bar — you notice you're holding two words that only point at each other, and you still have no way to tell them apart.

The move: Term T is defined as 'D', where D itself is T, a bare synonym of T, or resolves back to T within one or two further definitional steps (T =def D1; D1 =def T, or T =def D1; D1 =def D2; D2 =def T). The definiens (the defining phrase) presupposes prior grasp of the definiendum (the term being defined) instead of explaining it in independent terms.

Why it fails: A definition is supposed to let someone who does not already grasp a term come to understand it by way of terms they do already grasp. A circular definition substitutes the very term (or its synonym, or a short closed loop of mutually defining terms) back into its own explanation. Substituting the definiens for the definiendum anywhere it appears yields a sentence that still contains the undefined term, so no new information has been transmitted: the loop can be traversed endlessly without ever reaching ground. It becomes a live fallacy, rather than a merely poor dictionary entry, when the empty definition is then deployed to do argumentative work — treated as though it independently settles a contested case, when in fact it only restates the question.

Legitimate when: Circularity is not automatically vicious. Recursive definitions in mathematics and logic (e.g., defining a natural number as '0, or the successor of a natural number') are circular in surface form but legitimate because they bottom out in an independent base case and can be shown equivalent to a non-circular 'normal form.' Some theorists (revision theory) further argue that certain essentially circular definitions can still be meaningful, giving substantial guidance on a term's use across most cases even without a fixed, non-circular paraphrase. And any finite dictionary is full of small, unavoidable definitional circles among commonly understood terms (e.g., defining a 'nimbus cloud' as a cloud that produces precipitation) that cause no confusion and do no argumentative harm, because the circle closes among terms the audience already understands independently of the entry itself.

Ancient: Meno offers a third attempt at defining virtue: virtue is the power of attaining good things justly, where 'justly' is explained as acting virtuously. Socrates objects that this defines virtue by way of a part of virtue itself, so the search for what virtue is has made no progress and must start over. — Plato, Meno

Built from: Wikipedia · Stanford Encyclopedia of Philosophy — Definitions · Logically Fallacious — Circular Definition

Circular Reasoning

also known as: circulus in probando, vicious circle

The move: P because Q; Q because P.

Why it fails: The support relation forms a closed cycle without an independent ground.

Legitimate when: Mutual coherence may have evidential value only with independent constraints.

Commutation of Conditionals

The move: P → Q; ∴ Q → P

Why it fails: A conditional does not entail its converse.

Legitimate when: Valid only for a biconditional P ↔ Q.

Complex Question Fallacy

also known as: plurium interrogationum, many questions fallacy, loaded question

It's a question that sneaks in an assumption about you that nobody ever agreed was true — so any way you answer, it sounds like you admitted it.

In the roommates' group chat, someone types: "Can we all agree it's time you stopped eating my leftovers without asking?" Nobody has ever actually shown that this person has been doing that. But now, answering "yes" sounds like admitting they've been sneaking food, and answering "no" sounds like they're refusing to stop doing it. There's no reply in the chat that doesn't make them look guilty.

The tell: That trapped, slightly unfair feeling — like you got handed a question where every single answer makes you look bad, and you can't figure out how that happened.

The move: A question Q is posed whose felicitous answering presupposes some proposition P. P has not been independently established, proven, or granted by the respondent. Every direct answer available under the question's format (typically 'yes' or 'no') is then treated as if it conceded P, because the question's wording gives the respondent no way to answer without appearing to accept P.

Why it fails: A question is not itself an argument, so it cannot legitimately transfer commitment to P the way a supported premise can. The defect is that the question format forecloses the very move a fair exchange requires — contesting P on its own before answering anything that depends on it. Wikipedia's account of the complex-question fallacy notes this is context-dependent: presupposing something is not automatically fallacious (many ordinary questions presuppose uncontroversial facts), so the failure specifically occurs 'when someone asks a question that presupposes something that has not been proven or accepted by all the people involved.' Stanford Encyclopedia of Philosophy traces the structural root to Aristotle, who classed this among the fallacies not dependent on language: 'Aristotle's fallacy of many questions occurs when two questions are asked as if they are one proposition' — combining a claim-question and a follow-up question into a single grammatical unit so that answering the follow-up looks like it settles the claim too.

Legitimate when: The move is legitimate when the presupposition is already established, uncontroversial, or explicitly stipulated by the person answering — for instance, 'Who is the monarch of the United Kingdom?' presupposes there is a monarch, which is common ground, whereas 'Who is the King of France?' presupposes a false claim (per Wikipedia's contrast pair). It is likewise fair in a courtroom once the underlying fact has been admitted: Wikipedia notes the same question can be 'loaded in one context, but not in the other,' depending on whether the defendant has already admitted the conduct in question.

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Complex question · Wikipedia — Loaded question · Internet Encyclopedia of Philosophy — Fallacies

Conflicting Conditions

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Confusing an Explanation with an Excuse

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Confusing Currently Unexplained with Unexplainable

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Conjunction Fallacy

also known as: Linda problem

The move: P(A ∧ B) > P(A)

Why it fails: A conjunction cannot be more probable than either conjunct.

Legitimate when: Never valid under standard probability when the propositions are interpreted consistently.

Conspiracy Theory

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Contextomy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Deceptive Sharing

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Definist Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Denying a Conjunct

The move: ¬(P ∧ Q); ¬P; ∴ Q

Why it fails: The denial of the conjunction does not require the other conjunct to be true.

Legitimate when: Requires an independently established exclusive and exhaustive alternative.

Denying the Antecedent

Ruling out one reason something could happen doesn't rule out the thing happening.

In the office group chat, Deja types: "If the printer's jammed, the handouts won't print." Marcus checks the tray — no paper stuck anywhere. "It's not jammed," he says. "Great," Deja replies, "so it'll print fine." Except the toner cartridge is bone dry, which stops the print job just as dead as a jam would have — and the room is still handout-less when the meeting starts.

The tell: That itch you get when clearing away one explanation gets treated like the whole problem is solved — the same feeling as when one suspect gets an alibi and everyone acts like the case is closed, instead of asking who else could have done it.

The move: If P then Q; not P; therefore not Q. (P → Q, ¬P, ∴ ¬Q)

Why it fails: The conditional "if P then Q" asserts only that P is sufficient to produce Q — it never claims P is the only thing that can produce Q. Denying P and concluding not-Q treats the one-way conditional as though it were reversible (as though P ↔ Q), which the original statement never established. Q can be true through some route that has nothing to do with P, so P's falsity places no logical constraint on Q's truth value; any case where P is false and Q is true refutes the inference outright.

Legitimate when: The move is legitimate only when P is not merely sufficient but also necessary for Q — that is, when the converse (Q → P) independently holds, so the conditional is really a biconditional (P if and only if Q). This is common with stipulative definitions, formal rules, and narrowly bounded technical conditions where "if" is being used to mean "if and only if"; outside those cases, denying P tells you nothing about Q.

Built from: Wikipedia — Denying the antecedent · Wikipedia — List of fallacies · Stanford Encyclopedia of Philosophy — Fallacies · Internet Encyclopedia of Philosophy — Fallacies · Logically Fallacious — Denying the Antecedent

Denying the Correlative

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Disjunction Fallacy

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Distinction Without a Difference

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Double Standard

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Ecological Fallacy

also known as: ecological inference fallacy

The move: A group-level association is inferred to hold for individuals in the groups.

Why it fails: Aggregate correlations do not identify individual-level relationships.

Legitimate when: Individual-level data or a valid multilevel model supports the inference.

Equivocation

also known as: aequivocatio, equivocatio

Saying the same word twice but quietly switching what it means, so the point only seems to make sense.

A group chat is planning a hike. Jordan writes: "Painkillers get rid of headaches. My annoying coworker is a total headache. So I'm bringing painkillers for him tomorrow, ha." It gets a laugh, but if you slow down, "headache" meant an actual physical pain in the first sentence and just meant "an annoying person" in the second. Swap in the real meanings and the joke stops making sense — pills obviously don't fix an annoying coworker.

The tell: You laugh or nod along, then a beat later think "wait, that doesn't actually add up" — the sentence used the same word twice, but it feels like it snuck from one topic to a different one while your back was turned.

The move: A term T occurs at least twice in the argument (e.g., in two premises, or in a premise and the conclusion) carrying sense T1 at one occurrence and a distinct sense T2 at another. The argument's apparent force depends on treating T1 and T2 as if they were the same fixed meaning, so that the syllogism reads as valid on the surface while actually smuggling in a fourth term (quaternio terminorum) where only three are displayed.

Why it fails: The inference is only licensed if the repeated term denotes one and the same thing across every occurrence; that is what lets a middle term connect two premises or a premise connect to the conclusion. Once each occurrence is subscripted for its actual sense, the argument splits into two separate arguments, each missing a premise linking T1 to T2 — the semantic identity the inference relied on was never there, so what looked like one argument was really two half-arguments stitched together at a shared spelling.

Legitimate when: The term is used univocally throughout (one fixed sense everywhere), or a genuine shift in sense is flagged and separately defended rather than smuggled past the audience as if it were the same claim.

Ancient: Aristotle opens his catalogue of language-dependent fallacies with equivocation (homonymy), observing that because there are more things in the world than there are words for them, a single word inevitably ends up covering more than one thing — and a disputant can exploit that gap by sliding from one thing the word covers to another mid-argument, so the conclusion only seems to follow while the two senses stay unseparated. — Aristotle, On Sophistical Refutations

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Equivocation · Internet Encyclopedia of Philosophy — Fallacies

Etymological Fallacy

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Exclusive Premises

The move: Two negative categorical premises; ∴ a categorical relation between the end terms.

Why it fails: Two exclusions do not establish a relation between the excluded classes.

Legitimate when: No valid standard categorical syllogism has two negative premises.

Existential Fallacy

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Extended Analogy

Why it fails: The observed similarities or examples do not support the projected property with sufficient strength.

Legitimate when: Relevant similarities and background knowledge make the inference appropriately strong.

Fact-to-fiction Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Failure to Elucidate

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Fake Precision

Why it fails: The conclusion exceeds what the sample, probability model, or statistical design warrants.

Legitimate when: The design, assumptions, and uncertainty support the stated strength and scope.

Fallacy of (the) Undistributed Middle

also known as: undistributed middle, non distributio medii

The move: All A are B; All C are B; ∴ All C are A

Why it fails: The middle term B is not distributed, so sharing B does not connect A and C.

Legitimate when: A valid categorical mood distributes the middle term.

Fallacy of Composition

also known as: compositio, composition fallacy

Just because every little piece of something has a certain quality doesn't mean the whole thing has that quality too.

A friend is picking a fantasy sports lineup and says, "I picked the single best player at every position, so this has to be the best team ever." Then the team loses badly, because five ball-hogs who each average forty points a game on their own can't all take the last shot at the same time, and nobody passes. Great on their own, terrible stacked together.

The tell: You hear someone add up a bunch of "each one of these is great" and jump straight to "so the whole pile must be great," and something in you says wait, that's not how it works when you put them all together.

The move: Every part x of whole W has property F (F(x₁), F(x₂), ..., F(xₙ)); therefore the whole W has property F. The move treats F as if it were automatically preserved when parts are aggregated into a composite, without independently establishing that F is the kind of property aggregation preserves.

Why it fails: Whether a property transfers from parts to the whole depends entirely on what that property is, and this is never settled by the mere fact that every part has it. Some properties are aggregate-preserving (every part is made of matter, so the whole is made of matter); many are not, because the whole is a structured arrangement of the parts, not a mere heap, and arrangement itself can create properties absent from any part (emergence, e.g. no single neuron is conscious) or destroy/invert properties every part had (composition effects, e.g. every line item is affordable alone but the sum outstrips revenue; every individual can see better by standing, but not everyone can stand and see better at once). The inference supplies no reason to expect either outcome, so it is invalid unless a separate, property-specific argument for aggregate-preservation is added.

Legitimate when: The property in question is demonstrably aggregate-preserving in the relevant domain — genuinely additive or extensive properties like total mass, total volume, or total cost transfer straightforwardly from parts to whole because that is what such properties mean; the inference is safe only when this closure has been independently shown, not merely assumed by analogy with properties that do transfer.

Ancient: Aristotle lists composition among the language-dependent fallacies and illustrates it with sentences whose truth flips depending on whether words are taken separately or combined, such as the claim that a man can walk while sitting: true if 'able to walk' and 'sitting' are kept apart as separate facts about him, false if compressed into the single claim 'walking-while-seated.' Note this is Aristotle's own sense of the fallacy — a scope ambiguity about how words combine in a sentence — which historians of logic distinguish from the modern parts-to-whole inference described above; the two share a name and a family resemblance but are not the identical mistake. — Aristotle, On Sophistical Refutations, ch. 4

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Fallacy of composition · Internet Encyclopedia of Philosophy — Fallacies

Fallacy of Division

also known as: divisio, division fallacy

Assuming that because a group or a whole thing has some trait, every piece or member of it must have that same trait too.

A friend says, "Your book club is so smart — you guys read like three novels a month and always have deep discussions." Then she meets your friend Marco from the club at a party and says, "Oh, so you must be a huge reader and super into philosophy, right?" Marco actually just shows up for the snacks and rarely finishes the book. The club as a whole having a reputation for being well-read doesn't mean every single person in it is.

The tell: You notice someone is judging one specific person, item, or part based only on a label that describes the whole group or object — and you want to say "wait, you don't actually know that about him, you just know it about the group." It feels like they skipped a step: they never actually checked the individual, they just borrowed the group's reputation and pasted it onto him.

The move: The whole W (or the group G) has property F. X is a part of W (or a member of G). Therefore, X has property F.

Why it fails: The inference silently assumes that F is a distributive property — one that automatically passes from a whole or group to each of its parts or members — when in fact F may be a collective (or emergent) property that belongs to the whole only in virtue of how the parts are arranged, combined, or aggregated together. A team can be undefeated without every player being individually excellent; a chamber's low approval rating or gridlock describes the body's output as a collective, not a trait any single member need share. Because the argument never establishes that F actually distributes in this domain, the move from 'the whole has F' to 'the part has F' is a gap the premises do not license — the part is simply assumed to inherit whatever is true of the aggregate.

Legitimate when: The move is legitimate when the property really is distributive in that domain — genuinely and demonstrably true of each part simply because it is true of the whole (for example, 'this whole shipment is contaminated with substance X' licenses 'therefore this crate from the shipment is contaminated,' if contamination was established to be uniform throughout, or 'every part of this wall is painted blue' trivially licenses that any given brick-sized patch is blue).

Ancient: Aristotle's own example of division is about numbers, not groups and members: he shows how one could argue that five is both even and odd by wrongly dividing it into two and three — two is even, three is odd, so (improperly dividing the compound) five is said to be both. This is a syntactic move about how a composite term gets split apart, distinct from the modern collective-to-member inference that later logicians (from Whately onward) came to call the fallacy of division. — Aristotle, Sophistical Refutations, ch. 4 (fallacies dependent on language: division)

Built from: Wikipedia — Fallacy of division · Stanford Encyclopedia of Philosophy — Fallacies · Internet Encyclopedia of Philosophy — Fallacies

Fallacy of Every and All

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Fallacy of Four Terms

also known as: quaternio terminorum, four-term fallacy

The move: A purported categorical syllogism contains four distinct terms rather than exactly three.

Why it fails: No single middle term links the two premises.

Legitimate when: A categorical syllogism must have exactly three univocal terms.

Fallacy of Opposition

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

False Attribution

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

False Conversion

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

False Dilemma

also known as: false dichotomy, bifurcation fallacy

It's when someone hands you only two choices — usually one reasonable-sounding and one terrible — and hides the fact that other choices exist.

Your roommate says, 'Either we get a dog, or we're the kind of people who don't care about animals.' You never said you didn't want a dog. Maybe you're allergic, maybe your apartment is tiny, maybe you'd rather get a cat next year. None of that fits into either box you were just handed — but the way the sentence is built, saying 'no' to the dog suddenly makes you sound heartless.

The tell: You feel boxed in — like you're being hurried to pick from a menu with only two items on it, and the thing you'd actually say doesn't fit on either side. That cornered feeling is usually the first sign someone erased the middle ground on purpose.

The move: Presented as: (P ∨ Q), ¬P, ∴ Q — a disjunctive syllogism that is structurally fine. The defect sits one level up, in the unstated premise that P and Q are the only options and cannot both hold or both fail (i.e., that P ∨ Q is exhaustive and exclusive). Strip that assumption out and the argument is just P-or-Q with no support for why it must be P or Q at all.

Why it fails: The reasoning step is not broken; the menu is. The arguer treats two contraries (claims that could both be false, or that could both be true, or that leave room for a third) as if they were contradictories (claims where exactly one must be true). Once a genuine third option, a middle ground, or a point on a spectrum between P and Q is produced, the forced choice collapses — nothing about the logic itself was ever in question.

Legitimate when: When the two options genuinely are exhaustive and exclusive — a real logical complement (something either happened or it didn't), a law or rule that in fact only allows two outcomes, or a case where the arguer has independently proven that no third option exists. In those cases the same P ∨ Q, ¬P, ∴ Q form is simply sound disjunctive syllogism, not a fallacy.

Built from: Wikipedia — False dilemma · Internet Encyclopedia of Philosophy — Fallacies · Stanford Encyclopedia of Philosophy — Fallacies

False Effect

Why it fails: The evidence does not identify the claimed causal direction, mechanism, or counterfactual contrast.

Legitimate when: A credible experiment, quasi-experiment, mechanism, or identification strategy supplies the missing link.

False Equivalence

Why it fails: The observed similarities or examples do not support the projected property with sufficient strength.

Legitimate when: Relevant similarities and background knowledge make the inference appropriately strong.

Fantasy Projection

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Far-Fetched Hypothesis

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Faulty Comparison

Why it fails: The observed similarities or examples do not support the projected property with sufficient strength.

Legitimate when: Relevant similarities and background knowledge make the inference appropriately strong.

Gadarene Swine Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Galileo Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Gambler’s Fallacy

Believing a coin, wheel, or machine 'owes' you a different result after a bad streak, when it doesn't remember what happened last time.

Game night group chat: Jordan has lost the last five coin-flip challenges to decide who orders the pizza. 'No way I lose a sixth time,' Jordan says, offering to double the bet on the next flip. 'I'm statistically due.' But the coin has no idea Jordan lost five times in a row — it's the exact same fifty-fifty flip it always was, and it will be next time too.

The tell: The gut feeling is 'the odds have to even out soon' — but if you ask what would actually make that happen, nobody can point to any real connection between the last flip and the next one. The coin, the wheel, the dice have no memory, so there's nothing there to 'even out.'

The move: Given a sequence of trials from a fixed, memoryless process (P(A) constant and independent trial to trial), an observed run of outcomes ≠A is used to conclude P(A | history) > P(A) — i.e., the unconditioned probability of the next trial is treated as if it were conditional on the streak, when for genuinely independent trials P(A | history) = P(A) regardless of the history.

Why it fails: It substitutes an implicit 'law of averages' — the unfounded assumption that short-run frequencies must self-correct toward the long-run average — for the actual conditional probability of the next trial. It conflates two different facts: the a priori probability of a whole sequence (e.g., five heads in a row is unlikely, 1/32) with the conditional probability of the next single outcome given that the first four have already occurred (which, for an independent process, is unchanged, 1/2). Nothing in an independent, memoryless mechanism carries information from past trials into future ones, so there is no physical channel through which a 'correction' could occur.

Legitimate when: The reasoning is sound when the trials are actually dependent: sampling without replacement from a finite pool (cards, lottery balls already drawn), a mechanism that is physically wearing down or has been tampered with (so the streak is evidence the process itself changed), or when the streak is being used, correctly, as Bayesian evidence about an unknown parameter (e.g., a coin of unknown fairness) rather than asserted about a process already known to be fair and independent.

Built from: Wikipedia · Internet Encyclopedia of Philosophy — Fallacies

Genetic Fallacy

Deciding something is true or false just because of where it came from, instead of looking at whether it actually holds up.

Someone in the group chat shares a genuinely good budgeting tip. A friend replies, 'lol that's literally from a fortune cookie, you're taking financial advice from a cookie now?' and everyone laughs it off and moves on — nobody actually checks whether the tip itself makes sense. The advice didn't get worse because a cookie handed it out; it just stopped getting looked at.

The tell: You notice the conversation never actually touched the idea itself — no one said 'here's why that's wrong,' they just said 'look where that came from' and treated the case as closed. It feels like a joke landed, but nothing was actually checked.

The move: Claim P originated from source/circumstance S (a disreputable, embarrassing, biased, humble, or otherwise suspect origin). Therefore, P is false (or worthless) — or, in the mirror-image positive form: S is a reputable/noble/pure origin, therefore P is true (or worthy). Either way, a fact about P's genesis is substituted for an examination of P's content.

Why it fails: The truth or merit of a claim is a function of its content — what it asserts and what supports it — not of the causal or historical story behind how it came to be believed or proposed. Origin can bear on the *reliability of testimony* (a habitual liar's say-so is weaker evidence than an expert's), but even a corrupt, silly, or self-interested source can accidentally state something true, and even a noble or pure source can be wrong. The Internet Encyclopedia of Philosophy frames the defect precisely as attacking or defending a claim 'because of its origin (genesis) when such an appeal to origins is irrelevant' to the claim's actual merit. When the origin fact is treated as if it settled the question — rather than as one input to weigh alongside the content itself — the argument skips the only step that could actually verify or refute P.

Legitimate when: Origin is legitimate evidence — not conclusive proof — when it bears directly on the reliability of the testimony itself: a habitual fabricator's uncorroborated claim, a study funded by a party with a direct financial stake in the result, or a source demonstrated to lack the relevant competence all warrant heightened scrutiny or a demand for independent verification. The move only becomes fallacious when that scrutiny is skipped and the origin is treated as having already settled the claim's truth or falsity, rather than as a reason to check further.

Built from: Wikipedia — Genetic fallacy · Internet Encyclopedia of Philosophy — Fallacies

Gish Gallop

also known as: proof by verbosity

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Hasty Generalization

also known as: secundum quid, converse accident

Judging a whole group by the tiny handful of examples you happen to have run into.

Your friend orders from a new delivery app twice in one week, both times the food shows up cold, and she posts in the group chat: 'This app is always late and the food's always cold, never using it again, and neither should any of you.' Two orders, same neighborhood, same rainy week - and now the whole app is branded useless.

The tell: Something feels off because the number of examples is way too small for how sure the person sounds - it's the gap between 'this happened twice to me' and 'this is just how it is, always, for everyone.'

The move: A sample drawn from a population is observed to have property P in some proportion; the arguer then asserts that the population as a whole (or a future/unobserved instance) has P in that same proportion or with that same confidence, without the sample's size, selection method, or coverage actually licensing the jump.

Why it fails: The evidence base is too small, too narrow, or too self-selected to carry the weight of the claimed conclusion. The defect is a mismatch between the scope/confidence of the claim and the scope/confidence the sample can actually support - the sample may be accidentally biased (convenience sample, self-selected respondents, one time of day, one location) even when no one intends to mislead.

Legitimate when: When the sample is genuinely random or representative and large enough for the margin of error the conclusion implies, or when the conclusion is explicitly hedged to the sample's real coverage (e.g., 'in my limited experience,' 'in this pilot batch') rather than stated as a flat universal.

Ancient: Aristotle describes an error that runs the opposite direction from the fallacy of accident: instead of wrongly applying a general rule to a special case, the reasoner takes something true of one particular case - often one held under special or qualified conditions - and asserts it as an unqualified general rule. This ancient move is the root later loosely linked to what modern logic calls hasty generalization, though the two are not identical: Aristotle's concern is dropping a needed qualification, while hasty generalization is specifically about a sample too small or skewed to support a population-wide claim. — Aristotle, Sophistical Refutations (the 'converse accident' variant of secundum quid)

Built from: Wikipedia - Faulty generalization · Internet Encyclopedia of Philosophy - Fallacies · Stanford Encyclopedia of Philosophy - Fallacies

Having Your Cake

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Hedging

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Historian’s Fallacy

also known as: present knowledge projection

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Homunculus Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Hot Hand Fallacy

also known as: hot-hand belief

The move: A recent streak is treated as evidence that success probability has risen without adequate dependence evidence.

Why it fails: Clustering may occur under a stable random process.

Legitimate when: A properly analyzed mechanism or serial dependence supports a changing probability.

Hypnotic Bait and Switch

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Hypothesis Contrary to Fact

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Identity Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

If-By-Whiskey

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Illicit Contraposition

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Illicit Major

also known as: illicit process of the major term

The move: The major term is distributed in the conclusion but not in its premise.

Why it fails: The conclusion makes a stronger claim about the major term than the premises warrant.

Legitimate when: Every term distributed in the conclusion must be distributed in a premise.

Illicit Minor

also known as: illicit process of the minor term

The move: The minor term is distributed in the conclusion but not in its premise.

Why it fails: The conclusion makes a stronger claim about the minor term than the premises warrant.

Legitimate when: Every term distributed in the conclusion must be distributed in a premise.

Illicit Substitution of Identicals

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Imposter Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Incomplete Comparison

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Inconsistency

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Inflation of Conflict

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Insignificant Cause

Why it fails: The evidence does not identify the claimed causal direction, mechanism, or counterfactual contrast.

Legitimate when: A credible experiment, quasi-experiment, mechanism, or identification strategy supplies the missing link.

Jumping to Conclusions

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Just Because Fallacy

Why it fails: The evidence does not identify the claimed causal direction, mechanism, or counterfactual contrast.

Legitimate when: A credible experiment, quasi-experiment, mechanism, or identification strategy supplies the missing link.

Just In Case Fallacy

Why it fails: A disputed assumption, burden, category boundary, or conclusion is smuggled into the premises or procedure.

Legitimate when: The presupposition is established independently or stipulated by all parties.

Kettle Logic

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Least Plausible Hypothesis

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Limited Depth

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Limited Scope

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Logic Chopping

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Logical Fallacies Listing with Definitions and Detailed Examples

Why it fails: This record is an index or methodological item rather than a substantive fallacy.

Legitimate when: Not applicable.

Ludic Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Lying with Statistics

Why it fails: The conclusion exceeds what the sample, probability model, or statistical design warrants.

Legitimate when: The design, assumptions, and uncertainty support the stated strength and scope.

Magical Thinking

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

McNamara Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Meaningless Question

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Methodology

Why it fails: This record is an index or methodological item rather than a substantive fallacy.

Legitimate when: Not applicable.

Misleading Vividness

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Missing Data Fallacy

Why it fails: The conclusion exceeds what the sample, probability model, or statistical design warrants.

Legitimate when: The design, assumptions, and uncertainty support the stated strength and scope.

Modal (Scope) Fallacy

also known as: modal scope fallacy

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Moralistic Fallacy

also known as: ought-is fallacy

The move: The world ought to be P; ∴ the world is P.

Why it fails: A normative preference is substituted for descriptive evidence.

Legitimate when: Never as a bare inference; norms may instead motivate action to make P true.

Moving the Goalposts

also known as: raising the bar

Someone keeps raising the bar every time you clear it, so you can never actually win.

Your manager says, "Get five 5-star reviews from customers and the raise is yours." You work hard and get five. She looks them over and says, "Well, those were probably easy customers — get me five from people who complained first." You go get those too. Now it's, "Online reviews don't really count, I need in-person feedback forms." The goal was never really five reviews. It was whatever you hadn't done yet.

The tell: That queasy, deflating feeling of "wait, that wasn't the deal we agreed on" — you did the actual thing that was asked, and instead of a yes, you got a brand-new, harder ask that nobody mentioned before. If you rewind the tape, the finish line only ever moves after you reach it, never before.

The move: A standard S is set (explicitly or by clear implication) as what would suffice to establish claim C. The evidence required by S is then produced and meets it. Instead of accepting C, S is quietly replaced with a stricter, previously unstated standard S′, and C is declared unproven under S′ — with no reason for the change other than the fact that S was just satisfied. The pattern repeats: whatever is produced to meet S′ triggers S″, and so on.

Why it fails: The move treats the burden of proof as infinitely adjustable rather than fixed in advance, so the claim is rendered unfalsifiable in practice: the accept/reject decision was never actually tracking the strength of the evidence, it was tracking whether the responder wanted to keep dodging. This differs from an honest change of mind because it is the criterion, not the evidence, that is being manipulated — and it is manipulated for the same reason every time: because the prior criterion just succeeded. Structurally it is a covert, unilateral redefinition of what counts as 'enough,' introduced after the fact and applied only in the direction that keeps the original claim unresolved.

Legitimate when: Raising or tightening a standard is legitimate when the change is triggered by something other than the bare fact that the old standard was met — e.g. the original standard turns out to have been genuinely too weak (satisfied by evidence that later proves flawed, fabricated, or coincidental), new and relevant information becomes available that nobody could have anticipated, or the standard was explicitly provisional and flagged as open to revision from the outset. The test: would this same tightened standard have been announced even if the evidence had never been produced?

Built from: Wikipedia — Moving the goalposts · Logically Fallacious — Moving the Goalposts · Wikipedia — List of fallacies

Multiple Comparisons Fallacy

The move: One significant result is selected from many tests without correcting for multiplicity.

Why it fails: The chance of at least one false positive grows with the number of tests.

Legitimate when: Tests were preregistered or corrected using an appropriate procedure.

Naturalistic Fallacy

also known as: is-ought fallacy

The move: A normative property such as 'good' is identified with, or inferred solely from, a natural property.

Why it fails: The evaluative bridge or definition is assumed rather than defended.

Legitimate when: A defended normative bridge principle or stipulated technical definition is supplied.

Negating Antecedent and Consequent

The move: P → Q; ∴ ¬P → ¬Q

Why it fails: A conditional entails its contrapositive, not its inverse.

Legitimate when: Valid only when Q → P also holds.

Negative Conclusion from Affirmative Premises

The move: Two affirmative categorical premises; ∴ a negative conclusion.

Why it fails: Affirmative premises do not support an asserted exclusion.

Legitimate when: A negative conclusion requires a negative premise.

Nirvana Fallacy

also known as: perfect solution fallacy

The move: Reject real option A because it is imperfect compared with idealized option I.

Why it fails: The comparison uses an attainable option on one side and a frictionless ideal on the other.

Legitimate when: The ideal is feasible or serves only as an explicitly stated benchmark.

No True Scotsman

also known as: appeal to purity

When someone loses the argument about a whole group, they quietly shrink the group until the awkward example doesn't count anymore.

In the group chat, Marco says, 'Real foodies always try the street food when they travel.' Priya replies, 'I'm a foodie and I skipped the street stalls in Bangkok, my stomach can't handle it.' Marco types back, 'Yeah, well then you're not really a foodie, are you?' Two minutes ago Priya was one of them. Now she isn't. The only thing that changed is that she disagreed.

The tell: the sudden goalpost move. A second ago the person was clearly inside the group, no questions asked. Now they're suddenly outside it, and the only new fact is that they said something inconvenient. It feels like the rule got rewritten live, just for them.

The move: 1. A universal claim is asserted: all members of group G have property P. 2. A genuine counterexample x is produced: x belongs to G but lacks P. 3. Instead of retracting or qualifying the claim, the arguer redefines G ad hoc as 'true G,' stipulating that x does not really belong, so the universal claim survives unrevised and without independent justification for the new boundary.

Why it fails: The redefinition is not driven by any independent criterion of group membership; it exists only to exclude the counterexample that just appeared. This turns an empirical, checkable generalization into a disguised tautology — 'every true G has P' now means only 'every G-who-has-P has P,' which is true by stipulation and says nothing about the world. The arguer keeps the rhetorical force of the original claim while quietly discarding its content, and does so without ever presenting evidence that the counterexample was misclassified in the first place.

Legitimate when: Tightening a category is legitimate when the refined criterion is stated independently of the counterexample, is applied consistently to past and future cases alike, and tracks a real, checkable distinction (for example, a professional body's published certification standard) rather than merely re-describing 'has the disputed property.'

Built from: Wikipedia · Internet Encyclopedia of Philosophy - Fallacies · The Fallacy Files - No-True-Scotsman

Non Sequitur

also known as: non sequitur, it does not follow

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Notable Effort

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Nutpicking Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Overextended Outrage

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Oversimplified Cause Fallacy

The move: A complex outcome is attributed to a single cause while relevant causal factors are ignored.

Why it fails: The proposed cause does not explain enough of the contrast or mechanism.

Legitimate when: The single cause is shown to dominate for the specified contrast and scope.

Overwhelming Exception

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Package-Deal Fallacy

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Poisoning the Well

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Political Correctness Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Post Hoc

also known as: post hoc ergo propter hoc, after this therefore because of this, post hoc fallacy

Just because one thing happened right after another doesn't mean the first thing made the second thing happen.

Your coworker starts wearing a new pair of "lucky" socks on Monday, and the office wifi -- which had been flaky for weeks -- happens to run smoothly all day. By Wednesday he's telling everyone the socks fixed the wifi, and he's not wearing any other pair until further notice.

The tell: It feels like a story more than a real explanation -- there's a neat little sequence of events but nobody has said *how* the first thing could possibly bring about the second. If you ask "okay, but what's the connection?" and the only answer is "well, it happened right after," that's the tell.

The move: A occurred, then B occurred; therefore A caused B. (Temporal succession alone is treated as sufficient evidence of a causal relationship.)

Why it fails: Temporal priority is a necessary feature of many causal relationships but is never sufficient on its own to establish one. The inference ignores coincidence, common causes (confounders that produce both A and B independently), reverse or bidirectional causation, regression to the mean, and the simple fact that countless events precede countless other events without causing them. Establishing causation requires ruling out these alternatives -- through mechanism, controlled comparison, or repeated correlation -- not merely noting that one thing came before another.

Legitimate when: When temporal succession is paired with independent evidence for a causal link -- a known mechanism, a controlled or comparative design (e.g., the effect appears with the cause and disappears without it), ruled-out confounders, or a consistent dose-response/repeated pattern. Succession is then one legitimate piece of a larger causal case rather than the whole of it.

Ancient: Aristotle lists, among the merely apparent lines of argument speakers use, taking what is not the cause for the cause -- treating something as the cause of an event simply because it happened at the same time as, or just before, that event. His example: the orator Demades claimed that Demosthenes' policy was the cause of every disaster that followed, on no stronger ground than that war came after it. — Aristotle, Rhetoric II.24.8

Built from: Wikipedia: Post hoc ergo propter hoc · Stanford Encyclopedia of Philosophy: Fallacies · Aristotle, Rhetoric, Book 2, Chapter 24 (Perseus Digital Library)

Post-Designation

Why it fails: The conclusion exceeds what the sample, probability model, or statistical design warrants.

Legitimate when: The design, assumptions, and uncertainty support the stated strength and scope.

Pragmatic Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Prejudicial Language

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Proof by Intimidation

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Proof Surrogate

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Proving Non-Existence

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Pseudo-Logical Fallacies

Why it fails: This record is an index or methodological item rather than a substantive fallacy.

Legitimate when: Not applicable.

Psychogenetic Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Quantifier-Shift Fallacy

also known as: quantifier shift

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Quantum Physics Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Questionable Cause

also known as: cum hoc ergo propter hoc, correlation implies causation

The move: A and B covary; ∴ A caused B.

Why it fails: Association alone does not identify direction, mechanism, or confounding.

Legitimate when: A justified causal model, experiment, or identification strategy supports the claim.

Rationalization

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Red Herring

It's when someone answers a question you didn't ask, hoping everyone forgets the one you did.

In the family group chat, Mom asks Dad why he spent the vacation fund on a boat without telling anyone. Dad replies, 'You know, it's pretty telling that nobody in this family ever notices how many hours I put in at work.' Within minutes the whole chat is arguing about whether Dad works too hard, people are sending heart emojis, and the boat never comes up again.

The tell: The conversation has drifted somewhere louder and more emotional, and it feels vaguely related to what you were originally asking — but when you try to steer it back, you're suddenly the one who looks petty or cold for 'still going on about' your original question.

The move: The question at issue is P. The arguer introduces a different claim R that is related enough in tone or topic to seem connected to P but does not bear on whether P is true. The arguer then argues R at length — often persuasively and even correctly — and the audience, following the energy of the exchange, treats the resolution of R as though it had settled P, while P quietly goes unanswered.

Why it fails: The defect is pure irrelevance, not falsehood: R can be entirely true and R's defense can be entirely sound, and none of that gives any evidential weight for or against P, because there is no logical bridge — no entailment, no shared premise doing real work — connecting R's truth to P's truth. The Stanford Encyclopedia of Philosophy's discussion of fallacies of relevance and the Internet Encyclopedia of Philosophy both place this under the broader heading of ignoratio elenchi ('irrelevant conclusion' / 'missing the point'): the argument that gets made may be internally fine, it just isn't an argument about the thing in dispute.

Legitimate when: Raising a second issue is legitimate, not a red herring, when it is flagged honestly as a separate point ('that's a fair question, but first — a related issue matters here too') rather than substituted for an answer, or when R genuinely is a necessary precondition, scope qualifier, or piece of context that changes how P should be evaluated — for instance, pointing out that the premise of a question is itself false, or that a decision has a relevant cost the original framing ignored, can be a real contribution rather than a diversion, provided the original question still gets addressed afterward rather than being permanently abandoned.

Ancient: Aristotle diagnosed a family of fake refutations as arising from 'ignorance of refutation' (ignoratio elenchi): to truly refute a claim you must disprove that exact claim, so proving or attacking something merely adjacent to it only has the appearance of a refutation. He treated this failure as underlying a great many of the sophistical tricks he catalogued. The nineteenth-century English term 'red herring' names the everyday, informal version of that same ancient move — swapping in a related-sounding topic for the one actually in dispute — though the fishy name itself postdates Aristotle by roughly two thousand years. — Aristotle, Sophistical Refutations (Sophistici Elenchi)

Built from: Wikipedia — Red herring · Wikipedia — Irrelevant conclusion · Internet Encyclopedia of Philosophy — Fallacies · Stanford Encyclopedia of Philosophy — Fallacies

Reductio ad Absurdum

also known as: reductio ad absurdum, reduction to absurdity, proof by contradiction

The move: Assume ¬P; derive contradiction; ∴ P.

Why it fails: This is ordinarily a valid proof technique, not a fallacy, when the contradiction genuinely follows under the governing logic.

Legitimate when: The inference rules and background premises are legitimate.

Reductio ad Hitlerum

also known as: reductio ad Hitlerum, playing the Nazi card

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Regression Fallacy

Why it fails: The conclusion exceeds what the sample, probability model, or statistical design warrants.

Legitimate when: The design, assumptions, and uncertainty support the stated strength and scope.

Reification

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Relative Privation

also known as: appeal to worse problems, not as bad as

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Retrogressive Causation

Why it fails: The evidence does not identify the claimed causal direction, mechanism, or counterfactual contrast.

Legitimate when: A credible experiment, quasi-experiment, mechanism, or identification strategy supplies the missing link.

Righteousness Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Rights To Ought Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Scapegoating

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Selective Attention

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Self-Righteousness Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Self-Sealing Argument

Why it fails: A disputed assumption, burden, category boundary, or conclusion is smuggled into the premises or procedure.

Legitimate when: The presupposition is established independently or stipulated by all parties.

Shifting of the Burden of Proof

Why it fails: A disputed assumption, burden, category boundary, or conclusion is smuggled into the premises or procedure.

Legitimate when: The presupposition is established independently or stipulated by all parties.

Shoehorning

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Slippery Slope

also known as: thin end of the wedge, camel's nose

It claims one small step will snowball all the way to disaster, without ever showing why it has to.

A dad tells his teenager, 'If I let you stay out until 11 tonight, next week you'll want midnight, then you'll want to stay out all night, then you'll stop listening to any curfew at all.' The kid just asked for one extra hour tonight — nothing has actually shown that tonight's hour leads to any of the rest.

The tell: The conversation suddenly jumps from a small, specific ask straight to the worst possible ending, skipping over every place things could realistically stop along the way — and nobody ever explains why step one actually forces step two to happen.

The move: A₁ (a modest, often reasonable first step) will lead to A₂, which will lead to A₃, and so on down a chain to Aₙ, an extreme and clearly unacceptable outcome; because Aₙ must be avoided, A₁ itself must be rejected — with the whole chain asserted rather than established, transition by transition.

Why it fails: Each link in the chain (A₁→A₂, A₂→A₃, …) is treated as automatic or near-certain when no causal mechanism, comparative precedent, or absence-of-stopping-point has actually been shown for that specific transition. Even if every individual step sounds superficially plausible, the probability of reaching the terminal outcome is the product of all the transition probabilities, which can be vanishingly small even when each step feels intuitive in isolation. The argument borrows its persuasive force from vividness (a scary ending) rather than from any demonstrated chain of causation, and it silently ignores legal, institutional, physical, or psychological barriers that could halt the slide at any point.

Legitimate when: The chain is a genuinely evidenced causal, legal, or institutional sequence — each transition independently supported by mechanism, precedent, or data (e.g., documented cases of a specific legal exception being cited to justify broader exceptions, or a well-studied behavioral priming effect) — and the cumulative probability of the terminal outcome, once the transitions are actually multiplied out, remains high enough to be decision-relevant. In that case the argument functions legitimately to shift a burden of proof rather than to smuggle in an unsupported chain.

Ancient: In his dialogue on friendship, Cicero has the speaker Laelius reflect on Rome's political decline in terms of a slope: matters glide readily down the path of ruin once they have taken a start, an image later writers on the fallacy point to as the earliest recorded use of the slope metaphor for this kind of chained-decline reasoning. — Cicero, Laelius de Amicitia (XII.41, 44 BC)

Built from: Wikipedia — Slippery slope · Stanford Encyclopedia of Philosophy — Fallacies · Internet Encyclopedia of Philosophy — Fallacies

Special Pleading

Why it fails: A disputed assumption, burden, category boundary, or conclusion is smuggled into the premises or procedure.

Legitimate when: The presupposition is established independently or stipulated by all parties.

Spin Doctoring

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Spiritual Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Spotlight Fallacy

Why it fails: The conclusion exceeds what the sample, probability model, or statistical design warrants.

Legitimate when: The design, assumptions, and uncertainty support the stated strength and scope.

Statement of Conversion

Why it fails: The stated conclusion does not follow under the relevant formal inference rules.

Legitimate when: The missing premise or stronger relation is independently established.

Stereotyping (the fallacy)

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Stolen Concept Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Strawman Fallacy

also known as: straw man, straw person fallacy

Instead of arguing with what you actually said, someone argues with a dumber, more extreme version they made up and pretends they beat you.

In the family group chat, Grandma texts, 'Maybe we should do a smaller Thanksgiving this year, just the immediate family, so it's less chaotic.' Uncle Ray fires back, 'So you want to cancel Thanksgiving entirely and never see any of your grandkids again? Wow, Mom, that's cold.' Grandma never said anything close to that — she just wanted a smaller dinner — but now the whole chat is arguing about 'canceling Thanksgiving,' a fight nobody actually proposed having.

The tell: You get a weird jolt of 'wait, that's not what I said' — the reply is loud and confident and sounds like a win, but it's answering a version of your point that's way more extreme or way dumber than the one that actually came out of your mouth.

The move: Person A asserts position P. Person B substitutes a distorted, weakened, exaggerated, or wholly invented position P′ that superficially resembles P. Person B refutes P′. Person B (and the audience) treat the refutation of P′ as if it were a refutation of P.

Why it fails: The refutation and the target claim are not the same claim, so defeating P′ carries no logical weight against P at all. Even a flawless demolition of P′ leaves P completely untouched — the argument commits a relevance failure by attacking a proposition other than the one actually under discussion (the Stanford Encyclopedia of Philosophy classifies it as a variety of ignoratio elenchi, irrelevant conclusion). Two separate defects are usually present at once: the opponent does not actually hold P′, and even granting that P′ is false, its falsity does not transmit to P because there is no entailment or equivalence linking the two.

Legitimate when: Restating and then criticizing a different, weaker formulation of a claim is legitimate when the arguer explicitly flags the move as addressing a related-but-distinct position ('setting aside your main claim, consider this weaker version...'), or when the paraphrase is one the opponent has actually endorsed or that is strictly entailed by their stated view, so that refuting the paraphrase really does refute the original — this is the mirror-image legitimate technique sometimes called the 'principle of charity' or steelmanning, and its violation is precisely what makes straw-manning fallacious rather than merely disagreeable.

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Straw man · Internet Encyclopedia of Philosophy — Fallacies

Style Over Substance

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Subjectivist Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Subverted Support

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Sunk-Cost Fallacy

also known as: Concorde fallacy, sunk cost effect

The move: Irrecoverable past cost is used as a reason for future action.

Why it fails: Current choice should depend on prospective costs and benefits, not costs that cannot be changed.

Legitimate when: Past investment changes future payoffs, information, obligations, or switching costs.

Suppressed Correlative

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Survivorship Fallacy

also known as: survivorship bias

Why it fails: The conclusion exceeds what the sample, probability model, or statistical design warrants.

Legitimate when: The design, assumptions, and uncertainty support the stated strength and scope.

Texas Sharpshooter Fallacy

also known as: clustering illusion

Why it fails: The conclusion exceeds what the sample, probability model, or statistical design warrants.

Legitimate when: The design, assumptions, and uncertainty support the stated strength and scope.

Tokenism

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Traitorous Critic Fallacy

Why it fails: The offered consideration does not bear sufficiently on the proposition or decision actually at issue.

Legitimate when: The consideration is relevant under the governing evidential, legal, or practical standard.

Two Wrongs Make a Right

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Type-Token Fallacy

also known as: type-token confusion

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Unfalsifiability

Why it fails: A disputed assumption, burden, category boundary, or conclusion is smuggled into the premises or procedure.

Legitimate when: The presupposition is established independently or stipulated by all parties.

Unreasonable Inclusion Fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Unwarranted Contrast

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Use-Mention Error

also known as: use-mention confusion

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Weak Analogy

Why it fails: The observed similarities or examples do not support the projected property with sufficient strength.

Legitimate when: Relevant similarities and background knowledge make the inference appropriately strong.

Willed Ignorance

Why it fails: A disputed assumption, burden, category boundary, or conclusion is smuggled into the premises or procedure.

Legitimate when: The presupposition is established independently or stipulated by all parties.

Wishful Thinking

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Amphiboly

also known as: amphibolia, amphibology, syntactic ambiguity

The move: An inference depends on a sentence with more than one grammatical parse.

Why it fails: The conclusion is drawn from a reading not fixed by the premise.

Legitimate when: Context or syntax uniquely fixes the intended parse.

Fallacy of Combination

also known as: compositio, combination of words

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Figure of Speech Fallacy

also known as: figura dictionis, form of expression

Why it fails: The argument relies on a shift in meaning, grammatical structure, reference, scope, or level of description.

Legitimate when: The wording is unambiguous and the semantic relation is independently warranted.

Secundum Quid

also known as: secundum quid et simpliciter, qualified and unqualified statement, converse accident

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.

Ignoratio Elenchi

also known as: ignoratio elenchi, ignorance of refutation, irrelevant conclusion

The move: Premises support conclusion Q, but the dispute requires conclusion P.

Why it fails: Even a valid argument can fail as a refutation when it proves the wrong conclusion.

Legitimate when: Q entails or is the relevant form of P.

False Cause

also known as: non causa pro causa, false cause fallacy

Two things happening close together in time doesn't mean one caused the other — but this trick acts like it does.

In the group chat someone posts, 'Every time I wear my lucky socks, our trivia team wins. Socks are staying on forever now.' The team also happens to have its best player show up on sock nights. Nobody checks that — the socks get all the credit.

The tell: Two things happened near each other in time, and suddenly one gets blamed or praised for causing the other — with nobody asking whether something else was really going on, or whether it could be the other way around, or just plain luck.

The move: A is observed alongside, or shortly before, B (mere correlation, temporal succession, or co-occurrence); therefore A causes B — with the causal direction, the mechanism connecting them, and every rival explanation (reverse causation, a third factor producing both, coincidence, or regression to the mean) left unexamined.

Why it fails: Correlation and succession are consistent with several different causal stories — A causes B, B causes A, some C causes both A and B, or the link is coincidental / an artifact of small samples and natural fluctuation — and the argument never does the work of ruling the rivals out. Nothing has actually identified a mechanism by which A produces B, nor supplied the counterfactual (what would B have done if A had not occurred?) that a genuine causal claim requires. The observation is real; only the causal interpretation of it is unearned.

Legitimate when: The causal claim is backed by more than co-occurrence — a controlled or natural experiment, a documented mechanism, temporal precedence combined with ruled-out confounders, or a dose-response pattern — so that rival explanations (reverse direction, common cause, coincidence) have actually been checked and excluded rather than merely ignored.

Ancient: Aristotle names a refutation move he calls treating the non-cause as the cause (non causa pro causa): in a reductio-style argument, blaming an absurd result on some starting claim that actually played no part in producing it. This original sense is narrower than, and the historical ancestor of, the modern everyday habit of blaming a correlated or preceding event for something it may not have caused at all. — Aristotle, On Sophistical Refutations, ch. 5

Built from: Stanford Encyclopedia of Philosophy — Fallacies · Wikipedia — Questionable cause · Wikipedia — List of fallacies

Fallacy of the Consequent

also known as: fallacia consequentis, consequent fallacy

Why it fails: The label identifies a recurrent argumentative defect, but its exact failure condition requires context-specific analysis.

Legitimate when: The contextual inference license is stated and adequately supported.