our belief in the uniformity of nature are the same; we have a natural tendency to make it, and our experience is not inconsistent with it. What, again, are the characteristics of the third assumption: an hypothesis is true that explains the facts, and that takes its place easily and naturally among our other beliefs? They are the same. It is, of course, true that we are continually led by that assumption to adopt hypotheses that turn out to be false. But the principle itself is not discredited by experience. Experience only bids us act more cautiously in our application of the principle—bids us hold our believing propensity in check until we have collected as many pertinent facts as possible. But while this collection is being made, we shall be sure to feel that our hypothesis is true, so long as. it explains all the pertinent facts we know, although we may be conscious of our inability to justify it to others.
These, then, are the characteristics of the three assumptions, one of which underlies all reasoning whatever, and all of which underlie the reasonings of inductive science and every-day life. If we find any other assumption that has the same characteristics, we not only have a right to make it; we ought to do it, if we would avoid inconsistency. If any one objects that the particular assumption is incapable of proof, we can fairly reply that his objection is not to the point, unless he can prove the truth of the three assumptions that underlie all our inductive reasoning.
We may, then, sum up the conclusions so far reached as follows: Whatever we are asked to believe, ought to be a necessary truth, or an ultimate belief—a belief having the characteristics of being assumed through a natural tendency, and of not being interfered with by experience, or an hypothesis that explains all the pertinent facts and that takes its place easily and naturally among our other beliefs. Of both of the latter classes, it need hardly be said that the broader the base of the experience upon which the beliefs, in the negative sense explained, rest, the greater their credibility. If one man accepts one hypothesis because it explains all the facts he knows, and another man a different hypothesis because it
