Types d'erreurs logiques

Les erreurs logiques sont des arguments erronés, trompeurs ou faux qui peuvent être prouvés erronés avec un raisonnement. Ce sont les erreurs les plus courantes que vous devriez connaître.

Les arguments et les débats sont une partie importante du discours universitaire et universitaire. Mais tous les arguments ne sont pas parfaits. Certains peuvent être mis à part parce qu'ils ont des erreurs de raisonnement et de rhétorique. C'est ce qu'on appelle des “erreurs logiques” et elles sont très courantes.

Vous entendrez des erreurs logiques en classe, lors de débats télévisés et lors de disputes avec vos amis. Il peut même être difficile d'éviter de les utiliser vous-même.

Cet article présente certaines des erreurs logiques les plus courantes et comment les identifier.

===== Qu'est-ce qu'une erreur logique ?

Les erreurs logiques sont des arguments erronés, trompeurs ou faux qui peuvent être prouvés erronés avec un raisonnement. Il existe deux principaux types d'erreurs :

Une erreur formelle est un argument avec une prémisse et une conclusion qui ne résiste pas à un examen minutieux.

Une erreur informelle est une erreur dans la forme, le contenu ou le contexte de l'argument.

• Ad Hominem
• Strawman Argument
• Appeal to Ignorance
• False Dilemma
• Slippery Slope Fallacy
• Circular Argument
• Hasty Generalization
• Red Herring Fallacy
• Appeal to Hypocrisy
• Causal Fallacy
• Fallacy of Sunk Costs
• Appeal to Authority
• Equivocation
• Appeal to Pity
• Bandwagon Fallacy

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Une erreur ad hominem utilise des attaques personnelles plutôt que la logique. Cette erreur se produit lorsque quelqu'un rejette ou critique un autre point de vue basé sur les caractéristiques personnelles, l'origine ethnique, l'apparence physique ou d'autres traits non pertinents de la personne qui le détient.

Les arguments ad hominem sont souvent utilisés en politique, où ils sont souvent appelés « dénigrement ». Ils sont considérés comme contraires à l'éthique parce que les politiciens peuvent les utiliser pour manipuler les opinions des électeurs contre un adversaire sans aborder les problèmes fondamentaux.

Voyez si vous pouvez dire lequel de ces arguments est un argument ad hominem et lequel n'est qu'une insulte..

EXEMPLE 1

“Les racines de MacDougal pour une équipe de football britannique. De toute évidence, il n'est pas apte à être chef de la police en Irlande.”

EXEMPLE 2

“Tous les gens de Crète sont des menteurs.”

Un argument d'homme de paille attaque un sujet différent plutôt que le sujet discuté - souvent une version plus extrême du contre-argument. Le but de cette mauvaise orientation est de donner l'impression que sa position est plus forte qu'elle ne l'est en réalité.

L'argument de l'homme de paille porte bien son nom d'un épouvantail inoffensif et sans vie. Au lieu de lutter contre l'argument réel, ils attaquent l'équivalent d'un paquet de paille sans vie - une marionnette facilement vaincue pour laquelle l'adversaire ne s'est jamais disputé en premier lieu.

Voyez si vous pouvez détecter comment les deux déclarations suivantes pourraient être qualifiées d'arguments d'hommes de paille.

EXEMPLE 1

“Le sénateur pense que nous pouvons résoudre tous nos problèmes écologiques en conduisant une Prius.”

EXEMPLE 2

“Bien au contraire : le sénateur pense que l'environnement est une telle épave que le choix de la voiture ou les habitudes de conduite de personne ne ferait la moindre différence.”

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Un appel à l'ignorance (également connu sous le nom d '«argument de l'ignorance») soutient qu'une proposition doit être vraie parce qu'elle n'a pas été prouvée fausse ou qu'il n'y a aucune preuve contre elle.

L'argument peut être utilisé pour renforcer plusieurs conclusions contradictoires à la fois, telles que les deux affirmations suivantes :

“Personne n'a jamais été en mesure de prouver que les extraterrestres existent, donc ils ne doivent pas être réels.” “Personne n'a jamais été en mesure de prouver que les extraterrestres n'existent pas, ils doivent donc être réels.” Un appel à l'ignorance ne prouve rien. Au lieu de cela, cela déplace le besoin de preuve loin de la personne qui fait une réclamation.

crayon-alt icône Outil d'étude Lequel des exemples suivants est un appel à l'ignorance ?

EXEMPLE 1

“Nous n'avons aucune preuve que les Illuminati aient jamais existé. Ils ont dû être si intelligents qu'ils ont détruit toutes les preuves.”

EXEMPLE 2

“Je ne sais rien de Tank Johnson, sauf qu'il a un casier judiciaire aussi long que ta jambe, mais je parie qu'il est vraiment incompris.”

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Un faux dilemme ou une fausse dichotomie présente des options limitées - généralement en se concentrant sur deux extrêmes - alors qu'en fait, il existe plus de possibilités. L'expression « Amérique : aime-la ou laisse-la » est un exemple de faux dilemme.

Le sophisme du faux dilemme est un outil de manipulation conçu pour polariser le public, en promouvant un côté et en diabolisant un autre. C'est courant dans le discours politique comme moyen d'inciter le public à soutenir une législation ou des politiques controversées.

crayon-alt icône Outil d'étude Voyez si vous pouvez trouver une troisième option que ces exemples n'ont pas mentionnée.

EXEMPLE 1

“Soit nous partons en guerre, soit nous paraissons faibles.”

EXEMPLE 2

“Soit tu m'aimes, soit tu me détestes.”

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A slippery slope argument assumes that a certain course of action will necessarily lead to a chain of future events. The slippery slope fallacy takes a benign premise or starting point and suggests that it will lead to unlikely or ridiculous outcomes with no supporting evidence.

You may have used this fallacy on your parents as a teenager: “But you have to let me go to the party! If I don't go to the party, I'll be a loser with no friends. Next thing you know, I'll end up alone and jobless, living in your basement when I'm 30!”

pencil-alt icon Study Tool Which of these examples is a slippery slope fallacy and which is not?

EXAMPLE 1

“Your coach's policy is that no one can be a starter on game day if they miss practice. So if you miss basketball practice today, you won't be a starter in Friday's game. Then you won't be the first freshman to start on the varsity basketball team at our school.”

EXAMPLE 2

“If you miss practice, it means you were probably goofing off. People who goof off drop out of school and end up penniless.”

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Circular arguments occur when a person's argument repeats what they already assumed before without arriving at a new conclusion. For example, if someone says, “According to my brain, my brain is reliable,” that's a circular argument.

Circular arguments often use a claim as both a premise and a conclusion. This fallacy only appears to be an argument when in fact it's just restating one's assumptions.

pencil-alt icon Study Tool See if you can identify which of these is a circular argument.

EXAMPLE 1

“Smoking pot is against the law because it's wrong; I know it's wrong because it is against the law.”

EXAMPLE 2

“Smoking pot is against the law; this leads many to believe it is wrong.”

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A hasty generalization is a claim based on a few examples rather than substantial proof. Arguments based on hasty generalizations often don't hold up due to a lack of supporting evidence: The claim might be true in one case, but that doesn't mean it's always true.

Hasty generalizations are common in arguments because there's a wide range of what's acceptable for “sufficient” evidence. The rules for evidence can change based on the claim you're making and the environment where you are making it — whether it's rooted in philosophy, the sciences, a political debate, or discussing house rules for using the kitchen.

pencil-alt icon Study Tool Which of the following is a hasty generalization?

EXAMPLE 1

“Some people vote without seriously weighing the merits of the candidate.”

EXAMPLE 2

“People nowadays only vote with their emotions instead of their brains.”

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A red herring is an argument that uses confusion or distraction to shift attention away from a topic and toward a false conclusion. Red herrings usually contain an unimportant fact, idea, or event that has little relevance to the real issue.

Red herrings are a common diversionary tactic when someone wants to shift the focus of an argument to something easier or safer to address. But red herrings can also be unintentional.

pencil-alt icon Study Tool Which of the following examples is a red herring fallacy?

EXAMPLE 1

“My roommate wants to talk about cleaning out the garage, so I asked her what she wants to do with our patio furniture. Now she's shopping for new patio furniture and not asking me about the garage.”

EXAMPLE 2

“My wife wants to talk about cleaning out the garage, so I asked her what she wants to do with the patio furniture, because it's just sitting in the garage taking up space.”

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An appeal to hypocrisy — also known as the tu quoque fallacy — focuses on the hypocrisy of an opponent. The tu quoque fallacy deflects criticism away from oneself by accusing the other person of the same problem or something comparable.

The tu quoque fallacy is an attempt to divert blame. The fallacy usually occurs when the arguer uses apparent hypocrisy to neutralize criticism and distract from the issue.

pencil-alt icon Study Tool Which of the following is an appeal to hypocrisy?

EXAMPLE 1

“But, Dad, I know you smoked when you were my age, so how can you tell me not to do it?”

EXAMPLE 2

“Son, yes, I smoked when I was your age. It was dumb then and it's dumb now. That's why I forbid you to smoke, chew, vape, use nicotine gum, or do whatever you kids do with tobacco these days.”

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Causal fallacies are informal fallacies that occur when an argument incorrectly concludes that a cause is related to an effect. Think of the causal fallacy as a parent category for other fallacies about unproven causes.

One example is the false cause fallacy, which is when you draw a conclusion about what the cause was without enough evidence to do so. Another is the post hoc fallacy, which is when you mistake something for the cause because it came first — not because it actually caused the effect.

pencil-alt icon Study Tool Which kind of causal fallacy is at work in these examples?

EXAMPLE 1

“Jimmy isn't at school today. He must be on a family trip.”

EXAMPLE 2

“Every time a rooster crows, the sun comes up. Crows must be the creators of the universe.”

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A sunk cost fallacy is when someone continues doing something because of the effort they already put in it, regardless of whether the additional costs outweigh the potential benefits. “Sunk cost” is an economic term for any past expenses that can no longer be recovered.

For example: Imagine that after watching the first six episodes of a TV show, you decide the show isn't for you. Those six episodes are your “sunk cost.” A sunk cost fallacy would be deciding to finish watching anyway because you've already invested roughly six hours of your life in it.

pencil-alt icon Study Tool Which of these is a sunk cost fallacy and which is not?

EXAMPLE 1

“I know this relationship isn't working anymore and that we're both miserable. No marriage. No kids. No steady job. But I've been with him for seven years, so I'd better stay with him.”

EXAMPLE 2

“I'm halfway done with college. This is so tough, and it's not nearly as fun as I thought it would be, but I don't know. I guess I'll finish it and get my degree.”

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Appeal to authority is the misuse of an authority's opinion to support an argument. While an authority's opinion can represent evidence and data, it becomes a fallacy if their expertise or authority is overstated, illegitimate, or irrelevant to the topic.

For example, citing a foot doctor when trying to prove something related to psychiatry would be an appeal to authority fallacy.

pencil-alt icon Study Tool How do these statements mishandle authorities?

EXAMPLE 1

“Because Martin Sheen played the president on television, he'd probably make a great president in real life.”

EXAMPLE 2

“One day robots will enslave us all. It's true. My computer science teacher says so.”

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Equivocation happens when a word, phrase, or sentence is used deliberately to confuse, deceive, or mislead. In other words, saying one thing but meaning another.

When it's poetic or comical, we call this a “play on words.” But when it's done in a political speech, an ethics debate, or an economics report — and it's designed to make the audience think you're saying something you're not — that's when it becomes a fallacy.

pencil-alt icon Study Tool How does each of these examples commit an equivocation fallacy?

EXAMPLE 1

“His political party wants to spend your precious tax dollars on big government. But my political party is planning strategic federal investment in critical programs.”

EXAMPLE 2

“I don't understand why you're saying I broke a promise. I said I'd never speak to my ex-girlfriend again. And I didn't. I just sent her some pictures and text messages.”

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An appeal to pity relies on provoking your emotions to win an argument rather than factual evidence. Appealing to pity attempts to pull on an audience's heartstrings, distract them, and support their point of view.

Someone accused of a crime using a cane or walker to appear more feeble in front of a jury is one example of appeal to pity. The appearance of disability isn't an argument on the merits of the case, but it's intended to sway the jury's opinion anyway.

pencil-alt icon Study Tool Which of these is a fallacious appeal to emotion and which one is not?

EXAMPLE 1

“Professor, you have to give me an A on this paper. I know I only turned in a sentence and some clip art, but you have to understand, my grandmother suddenly died while traveling in the Northern Yukon, and her funeral was there so I had to travel, and my parents got divorced in the middle of the ceremony, and all the stress caused me to become catatonic for two weeks. Have some pity — my grandmother's last wish was that I'd get an A in this class.”

EXAMPLE 2

“Professor, I know this work was subpar, and I feel pretty bad about it. I'd like to schedule a meeting with you to discuss how I can do better on our next assignment.”

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The bandwagon fallacy assumes something is true (or right or good) because others agree with it. In other words, the fallacy argues that if everyone thinks a certain way, then you should, too.

One problem with this kind of reasoning is that the broad acceptance of a claim or action doesn't mean that it's factually justified. People can be mistaken, confused, deceived, or even willfully irrational in their opinions, so using them to make an argument is flawed.

pencil-alt icon Study Tool Which of these is a bandwagon fallacy?

EXAMPLE 1

“Almost everyone at my school will be at the party Friday night. It must be a popular thing to do.”

EXAMPLE 2

“Almost everyone at my school will be at the party Friday night. It must be the right thing to do.”

We hope this primer on logical fallacies helps you to navigate future disputes with friends, family, and online acquaintances without descending into vitriol or childish name-calling.

Knowing your logical fallacies can also help when you're working on your next research paper. You may want to brush up on controversial research topics while you're at it, so you're even more prepared.