But the boundary between psychology and philosophy is far less distinct. We constantly confound questions about the constitution of man, as known to us by experience, with questions about supposed intuitions of ultimate truth. The fact that sin causes remorse is interpreted as meaning that remorse actually is a knowledge of an avenging deity; and when the emotion is thus identified with the belief, it becomes easy to suppose that to destroy the belief is also to destroy the emotion. I think, indeed, that fallacies of that kind are among the commonest in philosophical writings. Now, of course, psychology has something to say in this matter. It may help, and I think that it has helped us to explain how men come to believe in anthropomorphic deities, and to invest them with the attributes of human rulers. But in that way it tends to show not that the conscience is caused by the belief, but to show how, under certain conditions, it has given rise to a belief by other than logical grounds. It suggests no probability that the conscience will disappear with the fallacy, but only that it will act differently when enlightened by a different logic. Conscience disappears no more than heat disappears, when both are explained; though the conduct which the emotions or the sensations determine will, of course, be affected. And now, I can say what I take to be the difficulty, and the escape. Mr. Balfour draws a kind of parallel between the scientific creed, which is, as he would put it, "based upon" a metaphysical doctrine, and the theological creed, which has a similar foundation. If the metaphysical foundation is so uncertain in both cases, must not the scientific be as uncertain as the theological? If we know nothing about atoms, or, on the other hand, about souls, we must be either sceptical in both cases, or credulous in both. There are the same underlying difficulties, and if we manage to overlook them in the case of science, why not overlook them in the case of theology? Conversely, if we elect to be sceptics in theology, how can we escape from scepticism in science? And, as a thorough-going scepticism is, doubtless, an impossible state of mind in practice, the conclusion of many people will be to accept belief in spite of certain gaps in our logical foundations. This, no doubt, is eminently convenient for the "constructive" process adumbrated by Mr. Balfour, which I certainly regard as extra-logical. But is any such dilemma really offered to us? The obvious answer is, that scientific truth, as Mr. Balfour admits, is not "based upon" metaphysical theory. The astronomical doctrine of a Newton remains equally valid, whatever is the ultimate nature of space or laws or atoms; whether we are materialists or empiricists or idealists. The philosophical "basis" is not really a set of truths which we must know before we can know the astronomical theory; but simply a set of hypotheses which have to conform to the truths given by experience.