Uses of argument

If you were trying to convince someone, perhaps a jury, of Natalie’s guilt, you might present them with the argument we discussed in the last section. Or, you might formulate this argument silently to yourself in the course of trying to figure out who killed Carl. In either case, we would say that you inferred that Natalie was Carl’s murderer from the premises that the murderer had access to the rose garden at midnight and that only Natalie had such access.

We tend to think of making arguments in situations where people disagree and are trying to convince each other (or to convince some third party). This is the case when people argue in court or around a dinner table, but this is not the only use of arguments, nor is it their fundamental use. Much of what we know is based on other knowledge and inference is the process by which we reach new knowledge from old. It is only because of arguments that we know many of the things we do, and it is only by further arguments that we can come to know many of the things we would like to learn.

Let’s survey some of the areas in which much of our knowledge is due to inference. Arguments like the one concerning Carl and Natalie enable us to know who committed crimes for which there were no eyewitnesses. In the natural sciences, almost everything we know beyond the basic data (consisting of observations and measurements) is reached by inference, as is much of our knowledge in higher mathematics. Our knowledge of the future is inferred from what we know about the past and present, and likewise our knowledge of the distant past (beyond the scope of our memories) is also based on argument. In some cases, we have firsthand accounts from people who claim to have observed or taken part in various historical events, but there are questions about the honesty and accuracy of these reports (especially when some contradict others), so we need arguments to determine which accounts we can rely on.

Inference is a crucial part of how you as an individual come to know the world. It’s a process that’s fallible and sometimes it results in errors—beliefs that aren’t really knowledge. When two people argue with one another—if they’re arguing honestly—they are each sharing some of the reasons they have for their beliefs. Each is trying to teach the other some of what he thinks he knows, and each can help the other identify errors in his own thinking.

Of course, people also often argue with one another dishonestly. Think of a conman who sells a bogus medicine and gives arguments to trick sick people into believing that his medicine will cure their illnesses. The conman knows that the conclusion he’s trying to convince them of is false—or, at least, he doesn’t really care if it is true. His goal is not to help them to tell what’s true, but to get them to believe a conclusion that he wants them to believe, regardless of whether it is true. It is possible to be dishonest with oneself in this same way. You may not be able to work to convince yourself of something you self-consciously know is a lie, but people often make arguments to convince themselves of things that they want to believe—or that they think they are supposed to believe—regardless of whether the things are really true. For example, someone who suspects her husband of having cheated may not want to believe it because she finds the idea too painful, or she may feel guilty for believing it because she thinks she is supposed to trust him. In either case, she may fish around for arguments to convince herself that he is faithful.

This brings me to an important point of clarification. Earlier I said that an argument is meant to give us a “reason to believe” its conclusion. When we speak of the reasons we have for performing an action, we usually have in mind either some goal that we hope to achieve by performing the action, or some obligation that we think we have for taking it. These are called pragmatic or practical reasons. In contrast, arguments give epistemic reasons, which help one to tell that a conclusion is true and thereby put one in a position to know it.

The primary use of arguments is to tell what is true. A secondary use is to persuade oneself or others that something is true. We can distinguish two forms of persuasion, which we might call "honest" and "dishonest." In honest persuasion, you articulate your own actual reasons for thinking the conclusion is true, in order to persuade someone else of it or to make it clearer in your own mind. In dishonest persuasion you come up with reasons to convince someone of something without regard for whether that thing is really true. Thus a dishonest lawyer or salesman might try to persuade someone of the innocence of his client or the quality of his wares by appealing to premises that he knows are false (or has no reason to think are true), but that he thinks his audience is likely to believe. Or he may use arguments that seem strong at first glance, but don't stand up to scrutiny. Not all sorts of dishonest persuasion stem from trying to make money or advance one's career (as these two cases do). People also argue dishonestly to impress others or to feel important themselves.

It is possible to engage in dishonest persuasion with oneself as well as with others. This often happens when someone wants to believe something (or thinks that he is supposed to believe it). Thus someone in an unhappy marriage might try to convince himself that he and his spouse are happy together, despite the growing evidence that they are not, or someone who has grown up in a family that professes certain beliefs and feels that he's supposed to believe them, might try to convince himself that they're true. We can call this dishonest reasoning with oneself, rationalizing, or BSing oneself. It is often hard to tell whether someone is being honest or dishonest in his use of arguments, and it can sometimes even be difficult to tell in one's own case. However, the essential difference between the two ways of arguing is clear: either arguments are used in an attempt to tell what's true (and to share this with others), or one using them to defend a position that one is committed to defending regardless of its actual merits. Genuine reasoning is the attempt to tell what's true, and dishonest uses of arguments are just attempts to fake (to oneself or others) that one is engaged in this process.