In a narrower sense, 'empiricism' is the method of resorting to _particular experiences_ for the solution of philosophical problems. Rationalists are the men of principles, empiricists the men of facts. (_Some Problems of Philosophy_, p. 35; cf. also, _ibid._, p. 44; and _Pragmatism_, pp. 9, 51.) Or, "since principles are universals, and facts are particulars, perhaps the best way of characterizing the two tendencies is to say that rationalist thinking proceeds most willingly by going from wholes to parts, while empiricist thinking proceeds by going from parts to wholes." (_Some Problems of Philosophy_, p. 35; cf. also _ibid._, p. 98; and _A Pluralistic Universe_, p. 7.) Again, empiricism "remands us to sensation." (_Op. cit._, p. 264.) The "empiricist view" insists that, "as reality is created temporally day by day, concepts ... can never fitly supersede perception.... The deeper features of reality are found only in perceptual experience." (_Some Problems of Philosophy_, pp. 100, 97.) Empiricism in this sense is as yet characteristic of Professor James's philosophy _as a whole_. It is not the distinctive and independent doctrine set forth in the present book. The only summary of 'radical empiricism' in this last and narrowest sense appears in the Preface to _The Meaning of Truth_ (pp. xii-xiii); and it must be reprinted here as the key to the text that follows.[1] "Radical empiricism consists (1) first of a postulate, (2) next of a statement of fact, (3) and finally of a generalized conclusion." (1) "The postulate is that _the only things that shall be debatable among philosophers shall be things definable in terms drawn from experience_. (Things of an unexperienceable nature may exist ad libitum, but they form no part of the material for philosophic debate.)" This is "the principle of pure experience" as "a methodical postulate." (Cf. below, pp. 159, 241.) This postulate corresponds to the notion which the author repeatedly attributes to Shadworth Hodgson, the notion "that realities are only what they are 'known as.'" (_Pragmatism_, p. 50; _Varieties of Religious Experience_, p. 443; _The Meaning of Truth_, pp. 43, 118.) In this sense 'radical empiricism' and pragmatism are closely allied. Indeed, if pragmatism be defined as the assertion that "the meaning of any proposition can always be brought down to some particular consequence in our future practical experience, ... the point lying in the fact that the experience must be particular rather than in the fact that it must be active" (_Meaning of Truth_, p. 210); then pragmatism and the above postulate come to the same thing. The present book, however, consists not so much in the assertion of this postulate as in the _use_ of it. And the method is successful in special applications by virtue of a certain "statement of fact" concerning relations.