Whether reading the editorial section of a newspaper, or perhaps an opinionated blog post, it is important to have a lookout for common logical mistakes in order to see if the argument has merit.

Logical mistakes, or logical fallacies, are a death sentence for any argument. An argument based on a logical fallacy is an argument built upon no foundation. There is no point in continuing the argument if the argument cannot at least be argued logically.

This post will point out the common fallacies I come across and give an example of the fallacy in use.

Red Herring

Tom: “I would like to build a fence on the United States and Mexican border.”
Jason: “Do you not realize the environmental impact of building a fence? And you people wonder why global warming is so bad?”

This fallacy is characterized by someone diverting the argument from one to another. For example, Tom is talking about illegal immigration. Jason, however, shifts the argument towards the environment.

Straw Man

Jessica: “I am for abortion.”
Amanda: “I’m pregnant. So are you saying you want to kill my child?”

In this example, Jessica is stating her position. However, Amanda distorts Jessica’s position and takes it to an extreme. Straw Man arguments take an argument to an extreme and try to make it personal.

Hasty Generalization

Amanda: “The majority of people at work want to be part of a new union.”
May: “Why do you think that?”
Amanda: “I was talking to a few of them at lunch.”

Hasty Generalization is making an argument seem valid when too few people have been consulted. The Hasty Generalization fallacy could have been true in this case if Amanda had talked to a few more of the workers. In this case, however, the sample size was too small to come to a conclusion that the workforce wanted to shift to a new union.

Poisoning the Well

Jill: “My boyfriend is such an idiot. You’ll see why when you meet him.”

Poisoning the Well is presenting negative information about a person before that person even has a chance to defend himself or his position. In the example, Jill poisoned the well to the friend listening by declaring that her boyfriend was an idiot before the other friend had a chance to meet him.

Ad Hominem

Tom: “I think marriage should be between man and a woman.”
Jason: “How can you say that? You’ve been divorced and remarried twice. So evidently, you think that marriage should be between man and three women.”
Tom: “I didn’t say that.”
Jason: “Whatever. You’re a moron.”

The Ad Hominem fallacy is a form of a personal attack. In this example, Tom is making a point that marriage should be between man and a woman. Rather than listen to Tom’s points supporting the argument, Jason attacks Tom personally in order to prove that Tom’s argument is false.

Division

Tom: “You must be a republican.”
Jason: “Why do you say that?”
Tom: “Because you live in Texas.”

Just because Tom lives in Texas doesn’t automatically make him a republican. The Division fallacy is committed when someone assumes what is true of the whole is also true of parts of the whole.

Composition

Amanda: “I think all bikers are scary. They all have tattoos, long beards, and leather jackets.”

A stereotype is a form of composition fallacy. Just because some bikers share a common characteristic does not mean that all bikers share that same characteristic.

Post Hoc (Superstition)

Amanda: “You broke my computer!”
Joey: “What makes you think that?”
Amanda: “You used it last. The next time I got on the computer, the screen just went blank and the computer started smoking.”

The Post Hoc fallacy is another term for superstition. Just because Joey got on the computer right before the computer fried does not mean that Joey caused the computer’s failure.

Appeal to Emotion

Jessica: “Please buy these magazines from me. I’ll be able to go on my trip and work my way through college.”

Please note that in the above argument, the person isn’t really arguing a point. The person is using emotion to win you over. Appeal to Emotion tries to persuade you using emotions rather than logic.

Begging the Question

Trevor: “Why do you think Bush invaded Iraq?”
Anthony: “Because he wanted to plunge this country into war.”

A person arguing using the Begging the Question fallacy does not really answer the question. Notice that Anthony didn’t really answer Trevor’s question. Anthony more or less reworded Trevor’s question into a phrase.

Two Wrongs Don’t Make a Right

Tom: “I’m not going to give my girlfriend a birthday present because she didn’t give me one.”

This fallacy is pretty self-explanatory on the basis that you can’t justify a position because you have been wronged in the past.

Appeal to Majority

Jason: “We should pull out of Iraq.”
Ashley: “Why?”
Jason: “Because most Americans do not support the war.”

The Appeal to Majority fallacy points out that you can’t base an argument on the amount of people behind it. It’s the same fallacy when some company declares, “10 million customers can’t be wrong.” The amount of customers (or downloads, or visits) does not determine the quality of a product and/or service alone.

Conclusion

Please note that the examples to each fallacy are in a vacuum and are out of context. In an argument, there are usually more factors that you have to gauge such as temperament, credibility, and bias. Even intuition can come in handy.

If you would like to read more on fallacies, please check out these two links: