Sadly, there is no uniformity of opinion in philosophy. A German aphorism defines a professor as someone who thinks otherwise, and this aphorism certainly applies to professors of philosophy. The historian Peter Geyl said that history—the academic field—was “argument without end.” This description fits philosophy better than it fits history. The German general Ludendorff told Clemenceau that the historians of the twenty-first century would say that the Great War was the fault of Britain and France. Clemenceau replied that he didn’t know what the historians of the twenty-first century would say, but he did know what they wouldn’t say: they wouldn’t say that Belgium had invaded Germany. The lesson of this well-known anecdote is that even in history there is a great deal that is beyond dispute. But in philosophy, there is really very little that is beyond dispute. If you want an argument for that thesis, I offer this one: there is very little that isn’t disputed. It is indeed possible in philosophy to advance good reasons for one’s views; unfortunately, in every case I know of in which one can do this, it is equally possible for the opponents of one’s views to advance good reasons for their views—and it never seems to be the case that the good reasons that can be advanced in support of a view decisively outweigh the good reasons that can be advanced in support of the opposing view. Of course, philosophers commonly think that their own views do have this feature: a philosopher who, for example, thinks that there is an objective morality will probably think that the reasons he or she has for thinking that there is an objective morality decisively outweigh the reasons that other philosophers have for thinking that there is no objective morality. But this philosopher will find it easy to believe this only if he ignores a very important question, to wit, If there are these good reasons for believing that there is an objective morality, and if they decisively outweigh the reasons that other philosophers have for thinking that there is no objective morality, and if they are the very reasons that you are in possession of and which convince you that there is an objective morality—why don’t they convince everyone, or everyone that [sic] can understand these reasons, or failing this, almost everyone? Shouldn’t reasons for believing something that decisively outweigh the reasons that support the opposing position have that power? We can confront our philosopher with this challenge: Why don’t all, or almost all, philosophers agree with you? What is it with these philosophers who take other positions than yours? Are they just stupid? Is it that they don’t understand the reasons you say decisively support the position you take? Are they intellectually dishonest? Are they psychologically weak—do they get some sort of psychological thrill or comfort from believing that there is no objective morality, and therefore hold on to this position even though it isn’t rationally defensible? Are they perhaps simply wicked? If you think any of these things—well, isn’t that convenient for you. If you’re right, then you’re smarter or nicer or more rational than a lot of other people in the same profession as yourself. Aren’t you lucky that it was you who turned out to be the smart or nice or rational one? And, of course, that there is an objective morality isn’t the only philosophical position you hold. You probably hold dozens of philosophical positions, all of which, you think, are decisively supported by the reasons you advance in support of them. And in each of these dozens of cases, there are other philosophers who hold positions inconsistent with yours. What an amazing coincidence: there is one person who holds the right position on dozens of questions, probably the only person who holds that particular combination of positions, and it just happens to be you.
(Peter van Inwagen, "Can Science Disprove the Existence of God?" Philosophic Exchange 34 [2004]: 39-53, at 49-50 [italics in original])
