Many court systems are adversarial. What this means is that the court features two “teams,” a prosecution and a defense. Each team tries its utmost to persuade a judge or jury that what they are saying is true. The prosecution tries to prove beyond any reasonable doubt that someone is guilty of having broken the law, and the defense tries to show that there are reasonable doubts about that person’s guilt and that the prosecutors have not proven their case. The article of faith that justifies such a context is that there is a truth about the person’s guilt or innocence, and the truth, or the facts, will enable one side or the other to provide a more compelling case to a judge or jury that is rational and impartial.
It is a noble ideal, and there are many ways in which our systems can fail to live up to it. Prosecutors might be extraordinarily talented and compelling orators who can persuade a jury to see things their way even when the truth is not on their side. The same goes for defenders who might be able to encourage great sympathy for the accused person or suggest grounds for doubt where really there should be none. Evidence can be fabricated or lost on purpose. And the judge or jury may not be impartial but may have their own interest in either convicting someone or letting them go free.
But it is hard to think of a better system. Imagine systems of “justice” that are based on some other contest. We could let the accuser and the accused engage one another in armed combat or in an arm-wrestling match and “let God decide.” We could simply ask the whole community to vote on guilt or innocence without working through the evidence. We could flip a coin. Any of these systems would generate verdicts, but the problem is we have no reason to think that the verdicts that are generated will have any connection to whether the accused person is really guilty or innocent. A system in which evidence and reasonable arguments are presented, and we do what we can to make sure rules of evidence are followed, and everything is out in the open, and the judge and jury are as impartial as we can practically guarantee, is a system that should generate verdicts that line up with actual guilt or innocence.
Philosophers tend to see their own disputes as very much like the adversarial system used in courts of law. Arguments are presented, objections are raised, replies to the objections are offered, the adequacy of those replies are assessed, and the discussion continues. The philosophers involved in the discussion are supposed to serve as judge and jury as well, which of course can mean that they are not completely unbiased as they present arguments and objections and are also supposed to rule on whether the arguments are compelling. But philosophers know they are supposed to be impartial in their rulings, and if they fail to be impartial, we can count on another philosopher to point this out quite forcefully. Daniel Dennett’s rules given above can be seen as rules that are meant to keep us on the straight and narrow path of impartiality.
But who is on trial? If we follow the example of Socrates, we shall say that our beliefs are on trial. A “guilty” verdict means that the belief should go away, and an “innocent” verdict means that it need not go away; the belief is defensible. The aim of the philosophical trial is not to put anyone in jail, of course, but to help each other to have beliefs that are defensible. The system of arguments and objections is certainly adversarial, but the adversaries should be friends, as they are trying to help one another.
The same concerns raised above can be raised here: this is a noble ideal which we can fail to live up to in many ways. Philosophers, like anyone, can become more concerned with scoring debate points than with getting at the truth, and some philosophers can make lousy arguments seem very compelling. But again, as with the court system, it is the best idea anyone has for arriving at defensible beliefs.
Note that both adversarial systems make the task of the prosecutor more difficult than the task of the defender. The prosecutor has to show that a person is guilty or that a certain belief is indefensible. The defender, on the other hand, does not have to show that the person is innocent or that the belief in question is true. That would be too much. In the case of courts of law, we make the job of the defender easier because, on the whole, we would rather have a guilty person go free (which is bad) than have an innocent person wrongly convicted (which is worse). In the case of a philosophical dispute, we would rather have someone believe something that is false but still defensible (which is bad) than face the challenge of proving something true before believing it (which is worse).
Why would it be worse to insist that we believe only what is proven to be true? Because, as we have seen through our study of skepticism, this will mean never being allowed to believe anything! We were able to escape the clutches of severe skepticism only by allowing ourselves to have beliefs that are defensible, or at least beliefs that fit with the other things we believe. While it is perhaps a comforting fantasy to imagine having iron-clad arguments for everything we believe, that is only a fantasy, and the bulk of human life as we know it is lived in a wide range between things we are sure are false and things we are sure are true. (Would it really be comforting to have iron-clad arguments? My own suspicion is that such a life would be bereft of stimulating doubts, wonderings, and possibilities!)