The conception of a "positive" philosophy--that is, a philosophy which confines itself to positive facts, and which is "agnostic" in the sense that it does not profess to know what it knows it does not know--is borrowed from science. It is an attempt to carry the methods of science into the domain of philosophy, to substitute science for philosophy. The attempt is made under the impression that science does not profess to know what it knows it does not know, _i.e._ makes no assumptions and takes nothing on faith. That impression, however, is, as we have argued in the last chapter but one, a false impression: the Uniformity of Nature is a pure--and rational--assumption. If, therefore, a philosophy confined itself strictly within the bounds of science, it would not be strictly positive or agnostic: it would still make some assumptions, even if only those made by science, and would still, even if it confined itself to the positive facts of science, be taking something on faith. A sound philosophy is one, not that makes no assumptions, but which seeks to find out what assumptions are made by any department of knowledge or practice--science, art, evolution, morality, religion--and how far those assumptions will carry us. The bane of philosophy is not making assumptions--all thought does--but is thinking you have made none. Common sense assumes that the testimony of consciousness, so far as it can be verified by consciousness, can be trusted as evidence of the reality of that which is presented to it. Positive or agnostic philosophies, whether of the optimistic or the pessimistic type, on the principle of making no assumptions, reject this one, either on the ground that the Real is Unknowable (which is itself an assumption as incapable of proof or disproof as the assumption that the Real is Knowable) or on the ground that we only know our states of consciousness, and cannot know whether there is or is not any reality beyond them (which again is simply an assumption that consciousness as evidence of a reality beyond itself is not to be trusted). Now, granted that common sense makes an assumption here, as it assuredly does, it is one such as can only be rejected by making a counter-assumption: to refuse to trust consciousness as evidence of a reality beyond itself is to make the assumption that it is not trustworthy--which may or may not be true, but is just as much an assumption as the supposition of its trustworthiness is. The positive and agnostic philosophies, therefore, do not succeed in avoiding assumptions in this matter: they only tacitly add another to that which they have already unconsciously made by assuming that Nature is uniform.