Abstract
Any review of philosophy since the eighteen-forties is bound to raise some challenging questions of a kind very different from those that would be raised by a consideration of, say, the development of physics or history during the same period. The story of the latter subjects would be an account of steady advance. It is true, certain puzzling problems would appear on the margins of both subjects, problems such as those concerning the meaning and range of applicability of physical concepts and those concerning criteria of truth and certainty in historical investigation; but these would of course be problems in philosophy, not in physics or history, and as philosophical problems they would display that peculiar recalcitrance that has marked such problems since they were first discussed in the cities of Ionia.