What is logical fallacy?

Logical fallacy definition

A logical fallacy is a rationally flawed and deceptive argument. Unlike a subjective argument which is disproven by facts, a logical fallacy is disproven through reasoning. Many people make logical fallacies erroneously simply by not thinking through their claim or not arguing it soundly enough. Others purposely use logical fallacies to sway other’s opinions.

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Arguing with logical fallacies is like playing with fire: Critical thinkers tear apart logical fallacies easily, while people who don’t think critically may believe a false claim and agree with your statement.

Aksapada Gautama first documented logical fallacies between the 6th century BCE and 2nd century CE in the Nyaya-Sutras, the foundational text of the Hindu school of philosophy. Since then, other philosophers such as Aristotle, Richard Whately, and Francis Bacon have all shaped our modern understanding of this argumentative technique.

Different types of logical fallacy

Just because a claim uses logical fallacy doesn’t mean the stance is invalid. It just means someone can break down the argument with logic. To steer clear of accidental logical fallacies in your work so opponents don’t tear it apart, familiarize yourself with the different logical fallacy forms.

Ad hominem

An ad hominem fallacy taints an opponent’s argument by striking at the opponent’s character rather than the argument at hand.

Example:

“We can’t take her budget proposal seriously because she got her college degree in art history.”

The fact that the opponent got a degree in art history has no bearing on her ability to put together a budget proposal, so the statement is logically unsound.

Red herring

Red herrings aren’t just for mystery novels; an argumentative red herring shifts the focus of the debate with an irrelevant point.

Example:

Robin says it’s hard to make enough money to buy a house in this economy. Robin’s parent replies, “When I was your age, I had a house, a car, a wife, and I was barely making minimum wage.”

While it may seem relevant at first, the parent’s statement isn’t a sound logical argument as to why it’s hard to make enough money to buy a house in the current economy. The parent’s circumstances were entirely different from Robin’s and hold no logical weight in this case.

Straw man

The straw man fallacy attempts to discredit the opposition’s argument by overexaggerating their claim to the point of inaccuracy.

Example:

A politician presents a stance to make immigration a more streamlined process, and their opponent rebuttals with, “So you’re proposing we just let everyone into the country now, including murderers?”

This logically unsound rebuttal is such an exaggerated and absurd interpretation of the immigration proposal, no one would go along with it.

Equivocation

One of the most nightmarish logical fallacies out there, equivocation muddies an argument’s validity through confusing phrasing with multiple interpretations.

Example:

“Clocks tick. Ticks hurt. Therefore, the passage of time brings pain.”

The example phrase mimics the format of logic but follows no actual logical pathway.

Slippery Slope

A slippery slope logical fallacy tacks on a series of additional claims unsupported by evidence.

Example:

If we legalize marijuana, in a couple of years everyone will be doing cocaine, overdosing on heroin, and burning down buildings.

While someone may have a logical reason for not wanting legalized marijuana, this example argument isn’t one of them. The additional claims that in a few years everyone will be doing more drugs and burning down buildings are unsubstantiated.

Hasty generalization

True to its name, a hasty generalization makes a statement based on just one or two examples rather than considering all the facts.

Example:

“Well I’m a man and I’ve never harassed a woman in my life, so ladies must be exaggerating about the amount of male harassment they encounter.”

The fact that the speaker is a man and has never harassed a woman may be true, but he’s just one person, not a whole sample size of people. The lack of sample size renders this argument logically flawed.

False Dilemma

Also known as a false dichotomy, this logical fallacy presents only two options when others exist.

Example:

“You’re either with us or against us.”

This statement ignores additional options such as neutrality or agreeing with some opinions but not all. The omission of other options makes the above statement unfounded by logic.

Bandwagon

The bandwagon logical fallacy argues that a statement is true because it’s popular.

Example:

“The movie is the best film of the year because it made the most money at the box office.”

This argument is logically flawed. Just because more people paid money to see one film over another does not mean the audience enjoyed it. Additionally, best film of the year is a subjective statement.

How to avoid logical fallacies

Unless you’re a very crafty debater, avoid logical fallacies during public speaking so opponents don’t poke holes in your otherwise sound stance. In writing, avoid logical fallacies because you won’t be present to clarify your stance and readers will leave with a negative impression of your work.

Make sure every argument has a claim, evidence, and warrant for why that claim is meaningful to your argument. Practice your presentation beforehand. Pretend you’re the opposition and to expose flaws in your original argument to you can adjust and make a stronger position.