What Have We Learned from Philosophy in the Twentieth Century?

In general, philosophy does not progress as the sciences do. Philosophers seem largely to follow fashions. Of course there are fashions in the sciences, too, but in philosophy they appear to predominate. So, when I look back at the two-thirds or more of the century that I remember, I see a succession of such fashions replacing one another. At the same time, I see something resembling progress in a couple of fields that I was involved in. Finally, I find us, at the close of the twentieth century, still burdened with one long-dominant attitude that many thinkers, in different ways, have tried (in vain) to overcome—an attitude reflected recently, in fact, in a particularly vocal fashion. Let me follow briefly each of these three lines of reflection