To avoid any misunderstanding as to the scope of the present book, let me say at the outset that with the exception of the Appendix, it is a critique, rather than a history. I have attempted not merely to summarize, but to estimate, present philosophical tendencies; and my criticism is throughout based on the realistic philosophy which I set forth constructively only at the end.

Since my method has been critical rather than expository I shall doubtless be charged with having committed the error personae, with having attributed to certain writers views which they would not recognize as their own. Be this as it may, I have in any case formulated the views which I have criticised, so that the merits of the question may always be in the foreground of study. I have assumed it to be more important to discover whether certain current views were true or false than to discuss with painstaking nicety the question of their attribution.