My title is intended to recall a well-known aphorism about philosophy, which runs something like this:

There is probably a correct version of this aphorism somewhere and an author to whose intentions what follows will do less than justice. I want to pick it up much as a composer might pick up a dimly remembered melody and I am going to develop it and produce my own variation on it. My topic is not centrally about loss of faith as generally understood, though it is centrally about the changing definitions of philosophy. My concern is with at least some of the reasons people have for doing philosophy and, in particular, about how their motives for doing philosophy connect with what philosophers think their subject is. My hope is that some light is thrown on this question by considering cases where people have changed their conception of philosophy—where, in other words, they have redefined their subject.

If I had to guess a rough date for the source of the aphorism with which I began, I would pick on late nineteenth or early twentieth century as the most likely. Much before then the problem of clergymen losing their faith would not be commonplace. On the other hand, the aphorism cannot be too recent since nowadays its point is somewhat blurred.