The concern of this chapter is the philosophy which Moore and Russell first developed in the course of their rejection of Idealism. In this development it was Moore who took the lead. In the Preface to The Principles of Mathematics, Russell says: 'on the fundamental questions of philosophy, my position, in all its chief features, is derived from Mr. G. E. Moore'. The greater part of this chapter is, therefore, devoted to an examination of the work of Moore from the period 1898-1903, especially the earlier part of this period. As in the rest of the book, I have confined my discussion to metaphysics, and excluded other issues except in so far as they are directly relevant to it. In the case of Moore this exclusion is important, for it means that I largely ignore his views on Ethics, which was perhaps his chief concern during this period. Moore's metaphysical views between 1898 and 1903 have a considerable degree of unity and inner coherence. Some changes occur, but I shall not emphasize these, for my aim is to convey the basic structure of Moore's metaphysics and its relation to Idealism. This discussion of Moore occupies Section 1 of this chapter; in the second, much briefer, section, I discuss Russell's Philosophy of Leibniz (1900).
G. E. Moore went up to Trinity College, Cambridge, in 1892, two years after Russell. He spent four years as an undergraduate, two working for the Classics Tripos (1892-4), and two working on Philosophy (1894-6). Early in 1894 he became a member of the society known as the Apostles (or simply as 'The Society'). The discussions of this society may have played as important a role in Moore's philosophical development as did his formal course of instruction. 1 Like Russell,