Take psychology as an instance. How does it happen that the physicist calmly develops his doctrine without finding it necessary to make his bow to philosophy at all, while the psychologist is at pains to explain that his book is to treat psychology as "a natural science," and will avoid metaphysics as much as possible? For centuries men have been interested in the phenomena of the human mind. Can anything be more open to observation than what passes in a man's own consciousness? Why, then, should the science of psychology lag behind? and why these endless disputes as to whether it can really be treated as a "natural science" at all? Again. May we assume that, because certain disciplines have taken a position of relative independence, therefore all the rest of the field will surely come to be divided up in the same way, and that there will be many special sciences, but no such thing as philosophy? It is hasty to assume this on no better evidence than that which has so far been presented. Before making up one's mind upon this point, one should take a careful look at the problems with which the philosopher occupies himself. A complete answer to the questions raised above can only be given in the course of the book, where the main problems of philosophy are discussed, and the several philosophical sciences are taken up and examined. But I may say, in anticipation, as much as this:-- (1) Philosophy is reflective knowledge. What is meant by reflective knowledge will be explained at length in the next chapter. (2) The sciences which are grouped together as philosophical are those in which we are forced back upon the problems of reflective thought, and cannot simply put them aside. (3) The peculiar difficulties of reflective thought may account for the fact that these sciences are, more than others, a field in which we may expect to find disputes and differences of opinion. (4) We need not be afraid that the whole field of human knowledge will come to be so divided up into special sciences that philosophy will disappear. The problems with which the philosopher occupies himself are real problems, which present themselves unavoidably to the thoughtful mind, and it is not convenient to divide these up among the several sciences. This will become clearer as we proceed. [1] "First Principles," Part II, section 37. CHAPTER II COMMON THOUGHT, SCIENCE, AND REFLECTIVE THOUGHT 7. COMMON THOUGHT.--Those who have given little attention to the study of the human mind are apt to suppose that, when the infant opens its eyes upon the new world of objects surrounding its small body, it sees things much as they do themselves. They are ready to admit that it does not know much _about_ things, but it strikes them as absurd for any one to go so far as to say that it does not see things--the things out there in space before its eyes.