A Brief History of Modern Philosophy/Introduction
The subject matter of the history of philosophy consists of the efforts which individual thinkers have made to explain or perchance to solve the ultimate problems of knowledge and of being. Modern philosophy—i. e. the philosophy of the last three centuries—has been specially concerned with four great problems. These problems, moreover—as I have shown in my Philosophic Problems (Eng. Tr. 1905)—are intimately related to each other, and there likewise exists a most significant analogy between them, in that the antithesis of continuity and discontinuity is of fundamental importance in each of them, except that it manifests itself under different forms.
1. The psychological problem originates from the inquiry concerning the essential attributes of psychic life. Is the soul a distinct substance, or does its essential nature consist of a peculiar activity? Is the soul composed of a variety of independent elements, or is it characterized by unity and totality? The discussion of these questions can be of value only as it is based upon a detailed investigation of psychical phenomena and functions. It will likewise appear that the solution of these questions has a very important bearing on the treatment and the solution of the remaining philosophic problems.
Whilst psychological investigation finds its subject matter in the bare facts of psychic life, there are two further problems which are conditioned by the antithesis of fact and value as it appears in psychic life, the problem of knowledge, and the problem of evaluation.
2. The problem of knowledge springs from the inquiry into the presuppositions of knowledge and the limits within which our thought processes are valid (thus including the sphere of psychological investigation). The primary origin of thought is spontaneous, a reaction produced by events which are not the result of thought. To what extent are we then justified in ascribing real meaning to the results of thought? Wherein does the truth of knowledge consist?
3. Whilst the problem of knowledge has special reference to the intellect, the problem of evaluation grows out of the inquiry into the validity of judgments pertaining to human conduct and social institution—particularly those that rest on the processes of will and emotion. What constitutes the standard for such a judgment? Upon what foundation does the validity of the concepts of good and bad rest? And is it possible to apply these concepts with logical consistency? The scope of the problem becomes increasingly comprehensive the moment we test the validity of the judgment, not only as pertaining to human conduct and vital forms, but likewise to Being and the universe in general. We then pass from the problem of ethics to that of religion.
4. Finally we may also inquire concerning the nature of Being, of which thinking, feeling and volitional being are but a single part. This gives rise to the problem of Being, i.e. the problem of cosmology or metaphysics. Is it possible to elaborate a general world theory according to scientific methods? And what would be the nature of such a theory? If we organize our experiences and infer the ultimate consequences of our knowledge, what principles will furnish an adequate explanation of the universe?
The nature and method of the treatment of these problems will vary with the instruments of knowledge and the historical conditions of the different periods. And in those problems which lie on the borderland of thought even the personality of the thinker will likewise have its effect. It is for this reason that a comparative treatment of the problems as history presents them is of such great importance. The various statements and solutions of the problem possess more than a purely philosophic interest. They have likewise an important bearing on the history of civilization and on psychology. They are responses in a great discussion which is proceeding through ages. Each response is something more than a mere intellectual structure, it is likewise the sign of a spiritual current. The history of philosophy therefore bears a direct relation to the general history of culture and of mind