Logical Fallacies

Logical fallacies are flaws in reasoning that weaken arguments. Strong arguments avoid them, while weak arguments often use them to appear stronger.

They are like tricks or illusions of thought, often used sneakily by politicians and the media to mislead.
The poster at yourlogicalfallacyis.com is designed to help identify and call out flawed logic.
The poster is published under a Creative Commons No Derivative Works license 2012 by Jesse Richardson.

Cherry Picking

Selective data clustering to suit an argument or finding a pattern to fit a presumption.

Also known as the Texas Sharpshooter Fallacy, named after a marksman shooting at a barn and then painting a bullseye around the most concentrated bullet holes.
Clusters naturally appear by chance and don’t necessarily indicate causation.
Example: Sugarette Candy Drinks pointing to research showing that of the five countries where Sugarette drinks sell the most units, three of them are in the top ten healthiest countries on Earth, therefore Sugarette drinks are healthy.. This is cherry-picking data.

False Dilemma

Presenting two alternative states as the only possibilities when more exist.

Also known as the either/or fallacy or false dichotomy.
This tactic appears logical but lacks possibilities beyond the presented choices.
Example: A leader rallying support undermines citizen's rights by telling people that they were either on the side of the leader or on the side of the enemy.

Begging the Question

A circular argument where the conclusion is included in the premise.

This illogical argument often arises from ingrained assumptions.
The argument is flawed because it assumes what it's trying to prove.
Example: "The word of Zorbo the Great is flawless and perfect. We know this because it says so in The Great and Infallible Book of Zorbo’s Best and Most Truest Things that are Definitely True and Should Not Ever Be Questioned."

Appeal to Nature

Arguing that something is valid, justified, inevitable, good, or ideal because it is ‘natural.’

Many ‘natural’ things are considered ‘good,’ which can bias thinking.
Naturalness itself doesn’t make something good or bad; murder is natural but not justifiable.
Example: A medicine man offering 'natural' remedies and claiming that people should be wary of 'artificial' medicine like antibiotics.

Anecdotal

Using personal experience or an isolated example instead of a valid argument, especially to dismiss statistics.

People often find testimonies more believable than statistical data.
Scientific and statistical measures are usually more accurate than individual perceptions.
Example: "Jason said that that was all cool and everything, but his grandfather smoked, like, 30 cigarettes a day and lived until 97 - so don’t believe everything you read about meta analyses of sound studies showing proven causal relationships."

Middle Ground

Saying that a compromise, or middle point, between two extremes must be the truth.

The truth often lies between extremes, but not always; sometimes something is simply untrue, and a compromise of it is also untrue.
Example: Holly claimed vaccinations cause autism, Caleb said this was debunked. Alice suggests the compromise that vaccinations cause some autism.

Gambler’s Fallacy

Believing that ‘runs’ occur to statistically independent phenomena such as roulette wheel spins.

This fallacy is based on misunderstanding probability; each spin is independent.
Example: Red had come up six times in a row on the roulette wheel, so Greg knew that it was close to certain that black would be next up; he lost his savings.

Bandwagon Fallacy

Appealing to popularity or the fact that many people do something as an attempted form of validation.

The popularity of an idea does not affect its validity.
Example: Shamus pointed a drunken finger at Sean and asked him to explain how so many people could believe in leprechauns if they’re only a silly old superstition.

Appeal to Authority

Saying that because an authority thinks something, it must therefore be true.

This shouldn't dismiss expert claims or scientific consensus if the authority has a demonstrated depth of knowledge.
Example: Not able to defend his position that evolution ‘isn’t true’ Bob says that he knows a scientist who also questions evolution (and presumably isn’t herself a primate).

Composition/Division

Assuming that what’s true about one part of something has to be applied to all, or other, parts of it.

What is true for the part does not necessarily apply to the whole without evidence.
Example: Daniel reasoned that atoms are invisible, and he was made of atoms and therefore invisible too. Unfortunately, despite his thinky skills, he lost the game of hide and go seek.

No True Scotsman

Making an appeal to purity as a way to dismiss relevant criticisms or flaws of an argument.

This fallacy is used as a last resort when a point has been lost.
New criteria are invoked to dissociate oneself or one’s argument from valid criticism.
Example: Angus declares that Scotsmen do not put sugar on their porridge, to which Lachlan points out that he is a Scotsman and puts sugar on his porridge. Furious, like a true Scot, Angus yells that no true Scotsman sugars his porridge.

Genetic Fallacy

Judging something good or bad on the basis of where it comes from, or from whom it comes.

Appealing to prejudices surrounding something’s origin is a red herring fallacy, similar to an ad hominem but applied to the source.
Example: Accused on the 6 o’clock news of corruption and taking bribes, the senator said that we should all be very wary of the things we hear in the media, because we all know how very unreliable the media can be.

Strawman

Misrepresenting someone’s argument to make it easier to attack.

Exaggerating, misrepresenting, or fabricating someone's argument makes it easier to present your own position as reasonable.
Example: After Will said that we should put more money into health and education, Warren responded by saying that he was surprised that Will hates our country so much that he wants to leave it defenceless by cutting military spending.

Post Hoc

Presuming that a real or perceived relationship between things means that one is the cause of the other.

Confusing correlation (things happening together) for causation (one thing causes the other).
Correlation can be coincidental or attributable to a common cause.
Example: Pointing to a fancy chart, Roger shows how temperatures have been rising over the past few centuries, whilst at the same time the numbers of pirates have been decreasing; thus pirates cool the world and global warming is a hoax.

Fallacy Fallacy

Presuming a claim to be necessarily wrong because a fallacy has been committed.

A false claim can be argued with logical coherence, just as a true claim can be justified with fallacies.
Example: Recognising that Amanda had committed a fallacy in arguing that we should eat healthy food because a nutritionist said it was popular, Alyse said we should therefore eat bacon double cheeseburgers every day.

Appeal to Emotion

Manipulating an emotional response in place of a valid or compelling argument.

Appeals include fear, envy, hatred, pity, guilt, etc.
Valid arguments can have emotional aspects, but emotion should not obscure reason.
Example: Luke didn’t want to eat his sheep’s brains with chopped liver and brussels sprouts, but his father told him to think about the poor, starving children in a third world country who weren’t fortunate enough to have any food at all.

Loaded Question

Asking a question with an assumption built-in, making it impossible to answer without appearing guilty.

Effective at derailing rational debates due to their inflammatory nature.
Example: Grace asked Helen, with Brad in earshot, whether Helen was having any problems with a fungal infection.

Ambiguity

Using double meanings or ambiguities of language to mislead or misrepresent the truth.

Politicians are often guilty of using ambiguity to mislead.
Example: When the judge asked the defendant why he hadn't paid his parking fines, he said that he shouldn't have to pay them because the sign said 'Fine for parking here' and so he naturally presumed that it would be fine to park there.

Burden of Proof

Saying that the burden of proof lies not with the person making the claim, but with someone else to disprove.

the person making the claim has the burden of proof, not the other way around.
The inability to disprove a claim does not make it valid.
Example: Bertrand declares that a teapot is, at this very moment, in orbit around the Sun between the Earth and Mars, and that because no one can prove him wrong his claim is therefore a valid one.

Moving the Goalpost

Moving the goalposts or making up exceptions when a claim is shown to be false.

People avoid being wrong by inventing ways to cling to old beliefs.
Example: Edward Johns claimed to be psychic, but when his ‘abilities’ were tested under proper scientific conditions, they magically disappeared. Edward explained this saying that one had to have faith in his abilities for them to work.

Ad Hominem

Attacking your opponent’s character or personal traits in an attempt to undermine their argument.

Attacks can be overt or cast doubt on character, undermining someone without addressing their argument.
Example: After Sally presents a case for a more equitable taxation system, Sam asks whether we should believe anything from a woman who isn’t married, was once arrested, and smells a bit weird.

Tu Quoque

Avoiding criticism by turning it back on the accuser – answering criticism with criticism.

This fallacy is a red herring that takes heat off the accused.
Example: Nicole identified that Hannah had committed a logical fallacy, but instead of addressing the substance of her claim, Hannah accused Nicole of committing a fallacy earlier on in the conversation.

Personal Incredulity

Saying that because one finds something difficult to understand, it’s therefore not true.

Understanding complex subjects requires effort; this fallacy is used in place of that effort.
Example: Kirk drew a picture of a fish and a human and with eusive disdain asked Richard if he really thought we were stupid enough to believe that a fish somehow turned into a human through just, like, random things happening over time.

Slippery Slope

Asserting that if we allow A to happen, then Z will consequently happen too, therefore A should not happen.

This reasoning avoids the issue and shifts attention to extreme hypotheticals.
Example: Colin Closet asserts that if we allow same-sex couples to marry, then the next thing we know we’ll be allowing people to marry their parents, their cars and even monkeys.