following dilemma. Either there is no rational foundation at all for the distinction between reality and appearance, and then all science is an illusion, or there is a rational foundation for it, and then we are logically bound to inquire into the principle of the distinction, and thus to face the problems of Metaphysics.[4] (_b_) What is essentially the same objection is sometimes put in the following form. Metaphysics, it is said, can have no place in the scheme of human knowledge, because all intelligible questions which we can ask about reality must fall within the province of one or other of the “sciences.” There are no facts with which some one or other of the sciences does not deal, and there is therefore no room for a series of “metaphysical” inquiries over and above those inquiries which constitute the various sciences. Where there are facts to investigate and intelligible questions to be put, we are, it is contended, in the domain of “science”; where there are none, there can be no knowledge. Plausible as this argument can be made to appear, it is easy to see that it is fallacious. From the point of view of pure Logic it manifestly contains a flagrant fallacy of _petitio principii_. For it simply assumes that there is no “science,” in the most universal acceptation of the term—_i.e._ no body of reasoned truth—besides those experimental sciences which have for their object the accumulation and systematisation of facts, and this is the very point at issue between the metaphysician and his critics. What the metaphysician asserts is not that there are facts with which the various special branches of experimental science cannot deal, but that there are questions which can be and ought to be raised about the facts with which they do deal other than those which experimental inquiry can solve. Leaving it entirely to the special sciences to tell us what in particular are the true facts about any given part of the world’s course, he contends that we still have to ask the more general question, what we mean by “real” and “fact,” and how in general the “real” is to be distinguished from the unreal. To denounce the raising of this question as an attempt to exclude certain events and processes from the “province of science,” is simply to misrepresent the issue at stake. Incidentally it may be added, the objection reveals a serious misunderstanding of the true principle of distinction between different sciences. The various sciences differ primarily, not as dealing with different _parts_ of the world of reality, but as dealing with the whole of it so far as it can be brought under different _aspects_. They are different, not because they deal with different sets of facts, but because they look at the facts from different points of view. Thus it would be quite wrong to suppose that the difference between, _e.g._, Physics, Physiology, and Psychology, is primarily that each studies a different group of facts. The facts