If we conclude that we are in a world in which God is revealed, if the orderliness of it is but another name for Divine Providence, we can scarcely feel the same as we would if we discovered in the world nothing of the Divine. I have in the last few pages been discussing the doctrine of purposes and ends, teleology, but I have said nothing of the significance of that doctrine for Theism. The reader can easily see that it lies at the very foundation of our belief in God. The only arguments for theism that have had much weight with mankind have been those which have maintained there are revealed in the world generally evidences of a plan and purpose at least analogous to what we discover when we scrutinize the actions of our fellow-man. Such arguments are not at the mercy of either interactionist or parallelist. On either hypothesis they stand unshaken. With this brief survey of some of the most interesting problems that confront the philosopher, I must content myself here. Now let us turn and see how some of the fundamental problems treated in previous chapters have been approached by men belonging to certain well-recognized schools of thought. And since it is peculiarly true in philosophy that, to understand the present, one must know something of the past, we shall begin by taking a look at the historical background of the types of philosophical doctrine to which reference is constantly made in the books and journals of the day. [1] Ostwald, "Vorlesungen ueber Naturphilosophie," s. 396. Leipzig, 1902. IV. SOME TYPES OF PHILOSOPHICAL THEORY CHAPTER XII THEIR HISTORICAL BACKGROUND 48. THE DOCTRINE OF REPRESENTATIVE PERCEPTION.--We have seen in Chapter II that it seems to the plain man abundantly evident that he really is surrounded by material things and that he directly perceives such things. This has always been the opinion of the plain man and it seems probable that it always will be. It is only when he begins to reflect upon things and upon his knowledge of them that it occurs to him to call it in question. Very early in the history of speculative thought it occurred to men, however, to ask how it is that we know things, and whether we are sure we do know them. The problems of reflection started into life, and various solutions were suggested. To tell over the whole list would take us far afield, and we need not, for the purpose we have in view, go back farther than Descartes, with whom philosophy took a relatively new start, and may be said to have become, in spirit and method, at least, modern.