Logical Fallacies

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In a predictable scene from any number of movies, TV shows, or actual lives, a teenager argues with her parents that she should be allowed to go to a party because all her friends are going. The exasperated parents roll their eyes and counter, “If your friends were all jumping off a bridge, would you jump too?” In their attempts to persuade, both the parents and the child fail miserably. In the eyes of the parents, “All my friends are going” is not a valid reason their kid should go to party, while comparing going to a party to jumping off a bridge makes no sense to the teenager.

Logical fallacies are invalid or deceptive forms of reasoning. Although they may, at times, be effective in persuading uncritical listeners, active audience members will reject you as a speaker as well as your argument when they hear a fallacy creep into your speech (Hansen, 2002). So be on the lookout for several types of logical fallacies as you listen to a speaker’s arguments and as you craft your own.

Bandwagoning. When our teenager uses “All my friends are going” as an argument, she’s guilty of using the bandwagon fallacy—accepting a statement as true because it is popular. Unfortunately, bandwagoning can sometimes persuade passive audience members who assume that an argument must be correct if others accept it (Hansen, 2002). But credible speakers and critical audience members must be careful not to confuse consensus with fact. That a large number of people believe in ghosts is not proof that ghosts exist.

Reduction to the Absurd. When the parents counter their daughter’s request to go to a party with friends by comparing it to jumping off a bridge with those friends, they are doing little to persuade her. That’s because they have extended their argument to the level of absurdity, a fallacy known as reduction to the absurd. Pushing an argument beyond its logical limits in this manner can cause it to unravel: the teenager sees no connection between going to a party (which is fun) and jumping off a bridge (which is extremely dangerous).

Red Herring. When a speaker relies on irrelevant information for his or her argument, thereby diverting the direction of the argument, he is guilty of the red herring fallacy (so named for a popular myth about a fish’s scent throwing hounds off track of a pursuit). If you say, for example, “I can’t believe that police officer gave me a ticket for going 70! Yesterday, I saw a crazy driver cut across three lanes of traffic without signaling while going at least 80. Why aren’t cops chasing down these dangerous drivers instead?” you would be using a red herring fallacy. There may well be worse drivers than you, but that doesn’t change the fact that you broke the law.

Personal Attacks. A speaker who criticizes a person rather than the issue at hand is guilty of the ad hominem fallacy—an attack on the person instead of on the person’s arguments. From the Latin meaning “to the man,” the ad hominem fallacy is a common feature of political campaigns. For example, if a speaker says, “Terry Malone is the better candidate for district court judge because she is happily married, whereas her opponent just kicked his wife out of their house,” the argument is focused on the individual’s marriage status, not the person’s particular qualifications for the job.

Begging the Question. Speakers who use the fallacy of begging the question present arguments that no one can verify because they’re not accompanied by valid evidence. For example, if Amanda notes, “People only watch The Vampire Diaries because Twilight is so awesome,” she’s basing her argument on an unprovable premise (the notion that Twilight is awesome—which is a subjective opinion, rather than a verifiable fact). If you accept Amanda’s premise, you must accept her conclusion. For this reason, this fallacy is often referred to as a circular argument.

Either-Or Fallacy. Speakers might try to persuade by using the either-or fallacy (sometimes called the false dilemma fallacy), presenting only two alternatives on a subject and failing to acknowledge other alternatives. For example, in a speech about local sports teams, Charlie notes, “In this town, you’re either a Bears fan or a Packers fan.” He fails to acknowledge that there might be fans of other football teams living in the city or individuals who don’t care about football at all.

Appeal to Tradition. A local community board informs a merchant group that existing “blue laws” preventing them from doing business on Sundays will continue because they have been on the books since the town’s founding. This kind of argument is a fallacy known as an appeal to tradition—an argument that uses tradition as proof. When speakers appeal to tradition, they are suggesting that listeners should agree with their point because “that’s the way it has always been.”

The Slippery Slope. The slippery slope fallacy is employed when a speaker attests that some event must clearly occur as a result of another event without showing any proof that the second event is caused by the first. For example, “Video surveillance cameras should not be installed in major metropolitan areas. The next thing you know, the government will be spending all of its time and money policing those camera feeds.”

Avoiding these logical fallacies goes a long way toward building ethos with your audience—particularly if the audience is hostile toward your speech topic. You want to rely on facts, research, honest emotion, and your own well-rehearsed presentation to persuade your audience. If you find yourself slipping into logical fallacy to persuade your listeners, you lack solid, compelling evidence in that area of your speech, and you should remedy the situation.