A scholarly philosophical discussion which is addressed to those who have a predisposition to guide their conduct by rational standards and the capacity to do so -- and who can think in abstractions, almost wholly devoid of those concrete examples on which most of us poor mortals lean. He shows how to establish criteria by which to distinguish between truth and error; how to study those criteria in terms of which such discrimination can be made. The rational use of knowledge and ideals in social policy justifies itself in enlightened action. And finally he makes a good case for the discipline of philosophy. A solid book, for scholars and philosophers.