Even mathematics, long the pattern of absolute knowledge, has not escaped the stigma of relativity. 'Metageometries' have been invented by Riemann and Lobatschewski as rivals to the assumptions of Euclid, and the brilliant writings of Poincaré have explained the human devices on which mathematical concepts rest. Euclidean geometry is reduced to a useful interpretation of the data of experience; it is not theoretically the only one. Its superior validity is dependent upon its use when applied to the physical world. Even mathematics, therefore, lend themselves to the philosophic inference drawn by Henri Bergson and others, that all conceptual systems of the human mind have a merely conditional truth, depending on the circumstances of their application.
2. Another fountain-head of Pragmatic philosophy has been Darwinism. Indeed, the Pragmatic is the only philosophizing which has completely assimilated Evolution. The insight into the real fluidity of natural species ought long ago to have toned down the artificial rigidity of logical classifications. To know reality man can no longer rest in a 'timeless' contemplation of a static system; he must expand his thoughts so as to cope with a perpetually changing process. Since the world changes, his 'truths' must change to fit it. He is faced with the necessity of a continuous reconstruction of beliefs. This influence of Darwin has inspired the logical theories of Professor Dewey and the 'Chicago School' of Pragmatists. Thought in their writings is essentially the instrument of this readjustment. Its function is to effect the necessary changes in beliefs as economically and usefully as possible. It is an evolving process which keeps pace with the evolution of reality and the changing situations of mortal life.
3. It is not, however, entirely the reaction of science upon philosophy which has given birth to Pragmatism. Philosophy itself has been rent by internal convulsions. These have been emphasized in the work of Dr. F.C.S. Schiller, who has shown that already in the days of Plato the distinction between 'truth' and 'error' was baffling philosophy, that Plato's Theaetetus has failed to establish it, and that the famous dictum of Protagoras, 'Man is the measure of all things,' distinctly foreshadows the 'Pragmatic,' or, as he calls it, the 'Humanist,' solution of the difficulty.
Elsewhere Dr. Schiller has commented on the controversies raised by Hume's criticism of dogmatism. He has shown that Kant failed to answer Hume because he accepted Hume's psychology, and that no a priori philosophers have since been able to devise any consistent and tenable doctrine. The idealistic theories of the 'Absolute' reveal their futility by their want of application to the genuine problems of life, and by the theoretic agnosticism from which they cannot escape. Hence the need for a new Theory of Knowledge and a thorough reform of Logic.
4. At this point he joins forces with Mr. Alfred Sidgwick, who has long been urging a radical criticism of the procedures of Formal Logic, and shown the gulf between them and the processes of concrete thought. Sidgwick has demonstrated that the belief in formal truth renders Logic merely verbal, and that the actual meaning of assertions completely escapes it.
5. The most sensational approach to Pragmatism, however, is that from the side of religion. The Pragmatic method of deciding religious problems, which asserts the legitimacy of a 'Faith' that precedes knowledge, has always been, more or less consciously, practised by the religious. It is brilliantly advocated in the Thoughts of Pascal, and clearly and forcibly defended in that most remarkable essay in unprofessional philosophy, Cardinal Newman's Grammar of Assent. This line of reasoning, however, is most familiarly associated with the name of William James; he first illustrated the Pragmatic Method by a famous paper (for a theological audience) on The Will to Believe, and founded the psychological study of religious experience in his Gifford Lectures on The Varieties of Religious Experience.
6. This brings us to the last, and historically the most fertile, of the sources of Pragmatism, Psychology. The publication in 1890 of James's great Principles of Psychology opened a new era in the history of that science. More than that, it was destined in the long run to work a transformation in philosophy as a whole, by introducing into it those biological and voluntaristic principles to which he afterwards applied the generic name of Pragmatism, or philosophy of action. We must pass, then, to consider the New Psychology of William James.