1.6 Avoiding Logical Fallacies

As mentioned in the last section, logical fallacies are errors in reasoning that weaken an argument and undermine the credibility of the author. Below are some of the most common logical fallacies. Learn to recognize these fallacies so that you can avoid them in your own writing.

Ad Hominem

An ad hominem fallacy is an attack on the person rather than on the person's argument.

• Candidate X was arrested for drunk driving in college—how can you even consider her ideas on tax reform?

• He can argue that giving special benefits to farmers is a bad idea, but what does he know? He isn't a farmer.

Straw Man

A straw man argument exaggerates the opposing argument to make it sound extreme or even ridiculous and then knocks the "straw man" down.

• Superintendent Y is against hiring more teachers; clearly she doesn't care if our kids are in huge classes with teachers who have no time to teach them.

• So you think doctors having liability insurance is a good idea? I guess you don't think doctors should take responsibility for their own actions when they kill someone on the operating table.

Hasty Generalization

A hasty generalization makes a conclusion from too little data.

• I've only known him for a few days, but I know he is the one for me. We completely understand each other.

• I just read an article that says listening to Mozart makes babies smarter. I am going to start playing Mozart all day for my baby.

False Cause/Post Hoc; Ergo Propter Hoc

The Latin phrase means "after this; therefore, because of this." In other words, because A happened before B, A must be the cause of B. Of course, often A has nothing to do with B.

• Soon after we moved to a neighborhood next to the factory, my hair started falling out. It must be the pollution from the factory that is making me go bald.

• During Governor B's time in office, unemployment has dropped 3 percent. Vote to re-elect Governor B so our economy will continue to grow.

False Dilemma

The false dilemma fallacy is also called the false either/or fallacy. It argues that there are only two possibilities in a situation, one of which is usually extreme. In reality, there are almost always more than two possibilities.

• I had to rob the pharmacy; I didn't have money for my wife's medicine. It was either that or let her die.

• Either we close the borders and refuse to let in any new immigrants, or we will have to let in everyone, including violent criminals and terrorists.

Circular Argument

The "reason" for the argument is just a restatement of the argument.

• Why is he famous? Well, everyone has heard of him.

• Funding is unavailable because we just don't have the money.

Glittering Generalities

Glittering generalities are vague phrases that work on the emotions of the audience. The words sound impressive, but really don't say much. They are useful when the speaker doesn't want the audience to think too carefully about what is being said. Glittering generalities are often used by politicians and advertisers, because each member of the audience can interpret the slogan in a different way.

• Together we will head into the future, building a new world for our children.

• Product A just makes life better.

Appeal to (False) Authority

The appeal to (false) authority is citing as an expert someone who is not really an expert.

• Joe Football says that the answer to global warming is solar power.

• I'm not a doctor, but I'm an actor who plays one on TV. I recommend Brand X for your cold.

Appeal to Ignorance/Untestable Hypothesis

The appeal to ignorance fallacy argues that because it can't be proven that something is false, it must be true. Or, it argues that because it can't be proven that something is true, it must be false.

• There is no way to prove that there is a God, so there must not be a God.

• There is no way to prove that there is no God, so there must be a God.

False Analogy

The false analogy fallacy is the use of an analogy that doesn't work, because the two things referred to in the analogy don't have the common link claimed by the writer.

• Giving a teenager the car keys is like giving a loaded gun to a crazy person.

• Investing in the stock market is like gambling on horse races. Either way, you are just throwing your money down the drain.

Moral Equivalence

The moral equivalence fallacy claims that two things are equally good—or, more often, equally bad—when they are not equal at all. Sometimes a person uses a moral equivalence fallacy to argue that his or her actions should not be condemned, because someone else's were just as bad. This is a specific type of false analogy, one that makes a moral or ethical comparison.

• My government teacher doesn't allow anyone to express an opinion that contradicts hers. It's like taking a class from Hitler.

• Why should he be blamed for saying disrespectful things about women? It's something all men do.

Slippery Slope

A slippery slope analogy claims that if we take one step in a certain direction, we start a process that cannot be stopped, and a terrible result is sure to follow.

• If we let them look in our baggage at the airport, before you know it they will be coming into our homes and looking under our beds.

• If you talk to boys, pretty soon you'll be flirting, and then holding hands—and before you know it you'll be a single mother living in a rat hole. Just don't talk to boys.

Bandwagon Fallacy

This refers to an old custom in political campaigns. The candidate would ride around town in a wagon big enough for a band of musicians. Those who supported the candidate would show their support by "jumping on the bandwagon." The bandwagon fallacy encourages people to adopt an opinion or buy a product or fote for a candidate because "everyone else" is doing it.

• Everywhere you go, you see people enjoying Product X.

• This is a must-see movie; more tickets have been sold in the first weekend than for any other movie this year.

Campaign Slogans

True to its history, the bandwagon appeal is often used in political campaigns:

• "For the president of the people" (Zachary Taylor, 1848).

• "A chicken in every pot and a car in every garage" (Herbert Hoover, 1928).

• "I like Ike" (Dwight D. Eisenhower, 1952). If everyone likes Ike, you should too.

• "The better man for a better America" (Bob Dole, 1996).

• "Yes, America can" (George W. Bush, 2004).

• "Yes, we can" (Barack Obama, 2008). 1