Scientific method in philosophy has been so greatly developed and widely accepted in our day that it seems almost ready to lay claim to the self-evidence which an older rationalism professed. It is my belief that it leaves out something essential to philosophy. I shall not attempt to define scientific method in philosophy, since it is a movement with several wings, rather than a definite set of propositions accepted by all its advocates; but its intent is clear. The theme of current criticisms of metaphysics and speculation has been that philosophy has no private access to the truth, no monopoly of such knowledge as human beings possess; it stands on an equal footing with the sciences. The observation is sound and timely; but from it has been drawn, at least by implication, the conclusion that there is no such thing as philosophy at all. For unless it has a peculiar method, or a distinct subject matter, or some other distinguishing trait, philosophy is only a convenient name for a certain group of men and the books they wrote. The criticism was made because philosophy had come to be identified with a set of dogmas. I wish to suggest instead that it is a peculiar kind of inquiry into a distinct subject matter. Philosophy is the attempt to formulate principles or categories which the philosopher already possesses, in common with everyone else, but in an unformulated state. Philosophy is always developing theories and systems, but they are tentative, not final and dogmatic; the categories are certain, but their statement is provisional; therefore, the process of inquiry is unending.