50 Fun Facts About Logical Fallacies

Which error is expecting heads to be 'due' after a fair coin lands tails five times in a row?

Gambler's fallacy is also called the Monte Carlo fallacy, after a 1913 night when a roulette wheel there landed on black 26 times running. Bettors lost millions of francs backing red.

Mike Godwin's internet 'law' says long online arguments eventually bring a comparison to which figure?

Adolf Hitler comparisons were so common on Usenet newsgroups that Godwin coined his rule to make people think harder before trivialising the Holocaust. Logicians call the move reductio ad Hitlerum.

William Cobbett's tale of throwing hounds off a scent with a pungent lure popularised which fallacy's name?

Red herring was the name of a strong-smelling smoked fish, which Cobbett claimed in 1807 he had dragged across a trail as a boy. In an argument it means an irrelevant point raised to divert attention.

Which fallacy turns 'we should trim military spending a little' into 'my opponent wants us defenceless'?

Straw man arguments swap the real position for a weaker one that is easy to knock down. In Britain the tactic is also called an Aunt Sally, after a pub game in which players throw sticks at a skittle on a post.

Which object did Bertrand Russell imagine orbiting the Sun to show where the burden of proof lies?

A china teapot too small for any telescope to spot was Russell's example: nobody can disprove it, yet nobody is obliged to believe it. He placed its orbit between Earth and Mars.

Which fallacy claims that letting students retake one quiz will end with nobody ever studying again?

Slippery slope arguments reject a small first step by insisting it must set off a chain reaction ending in disaster. The same move is known as the thin end of the wedge or the camel's nose in the tent.

Which fallacy answers a climate scientist's data by sneering about a messy divorce and unpaid parking fines?

Ad hominem is short for a Latin phrase meaning 'argument directed at the person': the reply goes after the speaker's character and leaves the evidence untouched.

Which error concludes that quitting college breeds success because a few dropout billionaires are famous?

Survivorship bias means judging from the winners while the failures stay invisible. Statistician Abraham Wald met it in World War II when studying bomber damage: only planes that made it home could be examined.

Which error keeps someone watching a dreadful film to the end because the ticket is already paid for?

Sunk cost fallacy is also known as the Concorde fallacy: Britain and France kept funding the supersonic jet long after it was clear there was no economic case for it.

The Flying Spaghetti Monster parody links global warming to the falling number of which group, mocking false causation?

Pirates have dwindled since the 1800s while temperatures rose, so founder Bobby Henderson drew a joke graph 'proving' one caused the other. The gag shows why two trends that rise together prove nothing.

Which fallacy do critics see in the ultimatum 'you are either with us or against us'?

False dilemma arguments pretend only two choices exist when others, such as staying neutral, are open. The same flaw is also called a false dichotomy or a false binary.

Which fallacy is trusting a diet claim just because a famous actor with no medical training backs it?

Appeal to authority goes wrong when the 'expert' is speaking outside any field of expertise: fame in films says nothing about nutrition. Logicians label this version an argument from false authority.

Which fallacy is an advert's claim that a phone must be the best because ten million people bought it?

Bandwagon appeals, in Latin argumentum ad populum, treat popularity as proof. Ten million buyers show what sells, which is a different thing from what is best.

Which Latin-named fallacy decides a rooster's crowing makes the sun rise because dawn always follows it?

Post hoc is short for post hoc ergo propter hoc, Latin for 'after this, therefore because of this'. Coming first is not the same as causing: the sun comes up whether or not the rooster does.

The 'hot hand' belief that one success makes the next likelier comes from which sport?

Basketball shooters were the subject of the 1985 paper by Gilovich, Tversky and Vallone that first described the hot hand as a fallacy. A 2018 reanalysis of their data found real evidence of streak shooting after all.

Which Greek philosopher first systematised logical errors into a list, in a work called Sophistical Refutations?

Aristotle drew up the list to help debaters refute opponents, and compared tricky arguing to unfair fighting in athletic contests. His book set sound reasoning against what it called the art of sophistry.

Which fallacy is 'this newspaper always tells the truth, because it says so on its front page'?

Circular reasoning begins with what it is trying to end with, so the argument proves nothing new. Its Latin name, circulus in probando, means 'circle in proving'.

The fallacy tu quoque answers criticism by calling the critic a hypocrite; what does its Latin name mean?

You also is the literal meaning of tu quoque, a move nicknamed the 'look who's talking' fallacy. A doctor who smokes can still be right that smoking is bad for you.

Which fallacy is deciding that a whole city is unfriendly after one rude taxi driver at the airport?

Hasty generalization builds a sweeping rule on one or very few cases, a textbook way of jumping to conclusions. A vivid personal story makes it worse; logicians call that version misleading vividness.

Which fallacy insists a herbal remedy must be safe because nothing in it was made in a laboratory?

Appeal to nature assumes that natural means good and synthetic means bad. The premise collapses quickly: many dangerous poisons are compounds found in the wild.

Which fallacy defends an itchy school uniform simply because pupils have worn it for a hundred years?

Appeal to tradition treats age as proof, and its Latin name is argumentum ad antiquitatem. Its mirror image, the appeal to novelty, claims an idea is better just because it is new.

Which fallacy claims a lake monster must exist because nobody has ever proved that it does not?

Appeal to ignorance treats a lack of disproof as proof. The same reasoning would 'prove' the monster is not there, since nobody has shown that it is: the evidence simply isn't in.

Which fallacy is 'a feather is light; whatever is light cannot be dark; so no feather is dark'?

Equivocation, literally 'calling two different things by the same name', slides between two senses of one word: here 'light' first means not heavy, then not dark. Logicians call the result a fallacy of four terms.

Which fallacy is an advert citing two studies that favour a pill while ignoring twenty that found no effect?

Cherry picking takes its name from the fruit harvest: someone shown only the ripest hand-selected fruit may wrongly assume the whole tree is that good. Logicians also call it the fallacy of incomplete evidence.

Which fallacy is demanding a transitional fossil, then demanding ten more as soon as the first is produced?

Moving the goalposts borrows from sports such as football and hockey: the goal shifts mid-game so one side can never score. In rugby, deliberately shifting the posts counts as a professional foul.

Which term, tied to Soviet replies to Western criticism, means deflecting blame with a counter-accusation?

Whataboutism earned its Cold War reputation when Soviet spokesmen met criticism of human rights abuses with charges against the West. A 1978 column in Australia's The Age applied the term to those tactics.

What is the literal meaning of non sequitur, the Latin label also given to jokes that come out of nowhere?

It does not follow is the translation, and in logic the phrase covers a conclusion with no real link to its premises. Comedians borrowed it for absurd lines unconnected to what came before.

In the story behind the Texas sharpshooter fallacy, what does the gunman do after firing at a barn wall?

Paints a target around the tightest cluster of bullet holes, then claims to be a crack shot. Researchers repeat the trick when they comb data for a pattern first and invent the hypothesis second.

Which fallacy concludes the sky must be green after one person calls it blue and another calls it yellow?

Middle ground reasoning assumes the truth always sits halfway between two claims. Logicians also call it the false compromise or the golden mean fallacy: when one side is simply right, splitting the difference is wrong.

Which fallacy rescues 'no vegan eats honey' by insisting that any honey-eating vegan was never a real vegan?

No true Scotsman comes from philosopher Antony Flew's example of a man who insists no Scotsman sugars his porridge and then, shown one who does, replies that no true Scotsman would.

Which English phrase, a 1500s rendering of the Latin petitio principii, strictly means assuming your own conclusion?

Begging the question is now widely used to mean 'raises the question', a sense that has nothing to do with logic. Read literally, the Latin original means something closer to 'assuming the original point'.

Which fallacy is a student asking for a higher grade because failing would upset a sick grandmother?

Appeal to pity, in Latin argumentum ad misericordiam, swaps evidence for sympathy. The grade is meant to measure the work, and the grandmother's health, however sad, says nothing about the essay.

Argumentum ad baculum, an appeal to force or threats, takes its name from the Latin word for which object?

A stick, or cudgel, stands for the threat behind the argument: agree, or something unpleasant follows. 'Back my plan or you're fired' is a reason to nod along, but no reason to think the plan is good.

Which error assumes a conclusion must be false simply because the argument offered for it was a bad one?

The fallacy fallacy is the playful nickname for what logicians formally call the argument from fallacy. A true claim can be defended badly, so spotting a flaw shows only that the argument failed.

Which astronomer's 'baloney detection kit' in The Demon-Haunted World teaches readers to spot common fallacies?

Carl Sagan took the phrase from a friend, who told him he dreamed of everyone carrying a baloney detection kit in their head. The book's kit pairs tools for testing claims with a list of traps to avoid.

Which Star Wars character names a jury-confusing legal 'defense' from a South Park parody of Johnnie Cochran?

Chewbacca living on Endor 'does not make sense', the cartoon Cochran tells the jury, so they must acquit. The 1998 episode gave lawyers a label for trying to confuse a jury instead of refuting the case.

Tversky and Kahneman's 'Linda problem' asks if Linda is likelier to have which job, or to have it and be a feminist?

A bank teller who is also a feminist can never be more probable than a bank teller alone, yet most people pick the detailed version because it sounds more like Linda. The slip is called the conjunction fallacy.

Which formal fallacy is 'if it rains the street gets wet; the street is wet; therefore it rained'?

Affirming the consequent, also known as the converse error, confuses a sufficient cause with a necessary one. A burst pipe or a street cleaner would leave the road just as wet.

Which error rejects seat belts as pointless because people will still die in some car crashes?

Nirvana fallacy was named by economist Harold Demsetz in 1969 for the habit of comparing real options with a flawless ideal. Voltaire made the same point: the best is the enemy of the good.

Which German philosopher catalogued 38 dishonest ways to win a debate in The Art of Being Right?

Arthur Schopenhauer wrote the treatise as sarcasm: the last trick on his list, once the argument is lost, is to turn personal, insulting and rude. He said he added ways to guard against such tricks.

Which philosopher's Essay Concerning Human Understanding gave logic its family of Latin-named 'ad' arguments?

John Locke described the moves as ways people prevail on others' assent or awe them into silence, without calling them fallacies. Later logicians did that, and his ad verecundiam, an 'appeal to modesty', became one.

Which British philosopher introduced the term 'naturalistic fallacy' in his book Principia Ethica?

G. E. Moore argued that philosophers who define 'good' as pleasant or desirable are making a mistake: goodness, in his view, cannot be reduced to any natural property and is simply ineffable.

French economist Frédéric Bastiat wrote a parable attacking the belief that which mishap is good for the economy?

A broken window brings the glazier six francs of work, Bastiat granted in 1850, but the shopkeeper would have spent that money elsewhere. Counting only the visible gain is still called the glazier's fallacy.

Which ancient puzzle, asking when a shrinking heap of sand stops being a heap, is linked to the continuum fallacy?

Sorites paradox takes its name from the Greek word for heap and is attributed to Eubulides of Miletus. The related fallacy argues that two states cannot be told apart because a continuum lies between them.

Samuel Johnson claimed to refute Bishop Berkeley's idealism by kicking which object, giving a fallacy its name?

A large stone met Johnson's foot with the words 'I refute it thus', as his biographer James Boswell recorded. Dismissing a claim as absurd without giving reasons is now called the appeal to the stone.

Which statistical error treats the odds of a chance DNA match as the odds that the matched suspect is innocent?

Prosecutor's fallacy was named in 1987 by William Thompson and Edward Schumann. A rare match still turns up among plenty of innocent people when enough of them are tested, so the two odds are very different.

Which fallacy, named by philosopher Nicholas Shackel, swaps a bold claim for a modest one whenever it is challenged?

Motte-and-bailey takes its name from a medieval castle: a tower on a mound, the motte, set in a wider enclosure, the bailey. Arguers enjoy the bold claim, then retreat to the safe tower when attacked.

Which debating tactic, named after a creationist, floods an opponent with more weak claims than can be answered?

Gish gallop was coined in 1994 by anthropologist Eugenie Scott after creationist Duane Gish, whom she called the technique's most avid practitioner. Refuting each claim takes far longer than making it.

Which Scottish philosopher warned that no claim about what 'ought' to be follows from what simply 'is'?

David Hume noticed that moral writers slide from 'is' to 'ought' without explaining the jump. The principle is now nicknamed Hume's guillotine: facts alone can never settle what anyone should do.

'All men are mortal; Socrates is a man; so Socrates is mortal' is the textbook example of which form of argument?

Syllogism comes from a Greek word for 'conclusion' or 'inference': two premises taken together force a third statement. A formal fallacy is a break in that structure, so the conclusion no longer follows.