In the previous chapter, you learned the components of a valid argument and how to test for its soundness. Once you can both empathetically understand an argument and critically evaluate its validity, you can begin to identify the fallacies it contains. Fallacies are failings or weaknesses in your argument.
It is particularly easy to slip up and commit a fallacy or false fallacy when you have strong feelings about your topic—if a conclusion seems obvious to you, you may be more likely to assume that it is true and to be careless with your evidence or premises. By learning to look for them in your and others’ writing, you can strengthen your ability to evaluate the arguments you make, read, and hear. It is important to realize two things about fallacies: first, fallacious arguments are very, very common and can be quite persuasive, at least to the casual reader or listener. You can find dozens of examples of fallacious reasoning in newspapers, advertisements, and other sources. Second, it is sometimes hard to evaluate whether an argument is fallacious. It requires not only careful examination of the argument but also your own interpretation of that argument. In addition, evaluating an argument is not generally binary but a sliding continuum. The goal is to identify arguments (our own or from others) that lie on the weak side of that continuum and adjust them so that they are stronger.
There are many kinds of fallacies, here we will just list a few of the most common.
The Straw Man
One way of making our own arguments stronger is to anticipate and respond in advance to the arguments that an opponent might make. In the straw man fallacy, the arguer sets up a weak version of the opponent’s position and tries to score points by knocking it down. But just as being able to knock down a straw man (like a scarecrow) isn’t very impressive, defeating a watered-down version of your opponent’s argument isn’t very impressive either.
A city has decided to reduce car traffic on a road that is particularly popular with cyclists. During a city council meeting, a local resident makes the following claim.
This city wants to prohibit the use of cars in favor of bikes.
The argument employs the Straw Man fallacy. The argument makes a weak representation of the opposing viewpoint in order to make their point stronger.
Hasty- or Overgeneralization
Making assumptions about a whole group or range of cases based on a sample that is inadequate (usually because it is atypical or too small). Stereotypes about people (“librarians are shy and smart,” “wealthy people are snobs,” etc.) are a common example of the principle underlying hasty generalization.
Two roommates attend a philosophy class, and they discuss their feelings. While doing so, one makes the following claim.
My roommate said her philosophy class was hard, and the one I’m in is hard, too. All philosophy classes must be hard!
This conclusion seems to carry weight, but two people’s experiences are, in this case, not enough to draw a reliable conclusion.
In false dichotomy, the arguer sets up the situation so it looks like there are only two choices. The arguer then eliminates one of the choices, so it seems that we are left with only one option: the one the arguer wanted us to pick in the first place. But often there are really many different options, not just two—and if we thought about them all, we might not be so quick to pick the one the arguer recommends.
While discussing the needs of the campus, committee members address the physical state of one of the buildings.
Caldwell Hall is in bad shape. Either we tear it down and put up a new building, or we continue to risk students’ safety. Obviously we shouldn’t risk anyone’s safety, so we must tear the building down.
The argument neglects to mention the possibility that we might repair the building or find some way to protect students from the risks in question—for example, if only a few rooms are in bad shape, perhaps we shouldn’t hold classes in those rooms.
The Latin name of this fallacy, "ad populum," means “to the people.” There are several versions of the bandwagon fallacy, but in all of them, the arguer takes advantage of the desire most people have to be liked and to fit in with others and uses that desire to try to get the audience to accept his or her argument. In one of the most common versions, the arguer tries to convince the audience to do or believe something because everyone else (supposedly) does.
While trying to justify his failure to stop at the stop sign, a man makes the following claim to a police officer.
I didn't do anything wrong! No one stops at that stop sign.
The behavior of most drivers may be relevant in determining whether or not a sign should be placed, but it does not determine the man's culpability. The arguer is trying to get us to agree with his conclusion by appealing to our desire to fit in with the majority.
Post Hoc (also called False Cause)
This fallacy gets its name from the Latin phrase “post hoc, ergo propter hoc,” which translates as “after this, therefore because of this.” Assuming that because B comes after A, A caused B. Of course, sometimes one event really does cause another one that comes later—for example, if I register for a class, and my name later appears on the roll, it’s true that the first event caused the one that came later. But sometimes two events that seem related in time aren’t really related as cause and event. That is, correlation isn’t the same thing as causation.
While discussing the current political situation, someone makes the following claim.
President Jones raised taxes, and then the rate of violent crime went up. Jones is responsible for the rise in crime.
The increase in taxes might or might not be one factor in the rising crime rates, but the argument hasn’t shown us that one caused the other. To avoid the post hoc fallacy, the arguer would need to give us some explanation of the process by which the tax increase is supposed to have produced higher crime rates. And that’s what you should do to avoid committing this fallacy: If you say that A causes B, you should have something more to say about how A caused B than just that A came first and B came later.
Ad hominem and tu quoque
The ad hominem (“against the person”) and tu quoque (“you, too!”) fallacies focus our attention on people rather than on arguments or evidence. In both of these arguments, the conclusion is usually “You shouldn’t believe So-and-So’s argument.” The reason for not believing So-and-So is that So-and-So is either a bad person (ad hominem) or a hypocrite (tu quoque). In an ad hominem argument, the arguer attacks his or her opponent instead of the opponent’s argument. In a tu quoque argument, the arguer points out that the opponent has actually done the thing he or she is arguing against, and so the opponent’s argument shouldn’t be listened to. Here’s an example: imagine that your parents have explained to you why you shouldn’t smoke, and they’ve given a lot of good reasons—the damage to your health, the cost, and so forth. You reply, “I won’t accept your argument, because you used to smoke when you were my age. You did it, too!” The fact that your parents have done the thing they are condemning has no bearing on the premises they put forward in their argument (smoking harms your health and is very expensive), so your response is fallacious.
When doing research for a paper, a student decides to ignore the findings of a particular author. To justify his or her decision, they present the following argument.
The author has low moral character. They have a proven record of poor behavior.
While the character of an author is an important factor when considering an argument from a faith-based point of view, it is not sufficient evidence to completely dismiss their argument. Instead, be sure to stay focused on your opponents’ reasoning, rather than on their personal character. The exception to this is, of course, if you are making an argument about someone’s character—if your conclusion is “President Jones is an untrustworthy person,” premises about her untrustworthy acts are relevant, not fallacious.