Document Type


Publication Date



Like many law professors, I have coached my share of moot court teams. As you probably know, in most competitions students either choose or are assigned one side of the case to brief. But for the oral argument segment of the competition, students must argue both sides of the case, “on-brief” and “off-brief,” often in alternate rounds.

At the end of a competition, with their heads still swimming with arguments and counterarguments, students will sometimes ask, “OK, so can you tell us which is the correct side?” I always say, “Of course I can. . . . The correct side is always the side you are currently arguing.”

Some students see this as a cynical response. But I remind them that a moot court issue is a special category of legal dispute. The reason the issue was chosen for the competition in the first place is the perception that there must be two very plausible sides to this issue. And I always go on to tell them that the lawyer's job as advocate is not to lead the court to some single absolute “truth”; rather, it is simply to convince the court why her client's position is more legally and logically correct than the opposing side's position.

The puzzle is this: why are human beings so good at reasoning in some situations and so consistently, hopelessly wrong in others? Mercier and Sperber provide an elegant solution: it is because the function of human reasoning is not to logically arrive at the “right” answer. On the contrary, the function of reasoning is to find support for an answer that the reasoner has already arrived at. In other words, the function of reasoning is argumentative. Its role is to create arguments intended to persuade. A skilled arguer is not necessarily after the truth; he is after arguments that support the views he already possesses so that he may convince others. Reasoning thus has a strongly social function.