Fallacies are common errors in reasoning that will undermine the logic of your argument. Fallacies can be either illegitimate arguments or irrelevant points, and are often identified because they lack evidence that supports their claim. Avoid these common fallacies in your own arguments and watch for them in the arguments of others.

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

After Bob said that we should put more money into health and education, Steve responded by saying that he was surprised that Bob hates our country so much that he wants to leave it defenceless by cutting military spending.

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

Sue asserts that if we lower the voting age to 16, 14-year-olds will want to vote, and then once we lower it to 14, we’ll find ourselves asking if we should lower it again to 12.

Special pleading.
Moving the goalposts to create exceptions when a claim is shown to be false.

Betty claimed to be psychic, but when her ‘abilities’ were tested under proper scientific conditions, they magically disappeared. Betty explained this saying that one had to have faith in her abilities for them to work.

The Gambler’s fallacy.
Believing that ‘runs’ occur in statistically independent phenomena such as roulette wheel spins.

Red had come up six times in a row on the roulette wheel, so Stan knew that it was close to certain that black would come up next. Suffering an economic form of natural selection with this thinking, he soon lost all of his savings.

Black-or-white.
Where two alternative states are presented as the only possibilities, when in fact more possibilities exist.

While rallying support for her plan to fundamentally undermine citizens’ rights, Nancy told her constituents they were either on her side, or on the side of the enemy.

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

Pointing to an unvetted chart, Roger shows how temperatures have been rising over the past few centuries, while at the same time the number of cattle with their flatulence has been increasing; thus cow farts are heating up the globe.

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

After Sally presents an eloquent and compelling case for tariffs, Sam asks the audience whether we should believe anything from a woman who isn’t married, smells funny, and is a bit overweight.

Loaded question.
Asking a question that has an assumption built into it so that it can’t be answered without appearing guilty.

Grace and Helen were both romantically interested in Brad. One day while Brad was sitting within earshot, Grace asked in an inquisitive tone whether Helen was still struggling with her dandruff problem and nail fungus.

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

Sean pointed a drunken finger at Patty and asked him to explain how so many people could believe in leprechauns if they’re only a silly old superstition. Sean, however, had had a few to many Guiness himself and fell off his chair.

Begging the question.
A circular argument in which the conclusion is included in the premise.

The word of Sham the Great is flawless and perfect. We know this because it says so in The Great and Infallible Book of Sham’s Best and Most Truest Things that are Definitely True and Should Not Ever Be Questioned.

Appeal to authority.
Using the opinion or position of an authority figure, or institution of authority, in place of an actual argument.

Not able to defend his position that the theory of evolution ‘is true’ Ron says that he knows a famous scientist and theologian who also believes in evolution.

Appeal to nature.
Making the argument that because something is ‘natural’ it is therefore valid, justified, inevitable, good, or ideal.

The medicine man rolled into town on his bandwagon offering various remedies including very special plain water. He said that it was only natural that people should be wary of all ‘artificial’ medicines.

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

Daniel was a precocious child and had a liking for logic. He reasoned that atoms are invisible, and that he was made of atoms and therefore invisible too. Unfortunately, despite his thinking skills, he lost the game of hide-and-go-seek.

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

Taylor said that that was all cool and everything, but her 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.

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

Luke didn’t want to eat his sheep’s brains with chopped liver and brussel 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.

Tu quoque.
Avoiding having to engage with criticism by turning it back on the accuser – answering criticism with criticism.

The blue candidate accused the red candidate of committing the tu quoque fallacy. The red candidate responded by accusing the blue candidate of the same, after which ensued an hour of back and forth criticism with not much progress.

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

Steven declares that a squirrel 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 valid.

No true Scotsman.
Making what could be called an appeal to purity as a way to dismiss relevant criticisms or flaws of an argument.

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.

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

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.

The Texas sharpshooter.
Cherry-picking data clusters to suit an argument, or finding a pattern to fit a presumption.

The makers of Sickly Sweet Drinks point to research showing that of the five countries where Sickly Sweet drinks sell the most units, three of them are in the top ten healthiest countries on Earth, therefore Sickly Sweet drinks are healthy.

The fallacy fallacy.
Presuming that because a claim has been poorly argued, or a fallacy has been made, that it is necessarily wrong.

Recognizing that Melinda had committed a fallacy in arguing that we should eat healthy food because a nutritionist said it was popular, Karen said we should therefore eat bacon double cheeseburgers every day.

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

Frank said to Stuart, “I don’t see how one man’s death could possibly atone for the sins of the whole world. He’s only one person.”

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

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.

Middle Ground.
Saying that a compromise, or middle point, between two extremes is the truth.

Marylin said that vaccinations caused autism in children, but her friend said that this claim had been debunked and proven false. Their friend Natalie offered a compromise that vaccinations cause some autism.