know on what evidence an ethical proposition rests, until we know the nature of the notion which makes the proposition ethical. We cannot tell what is possible, by way of proof, in favour of one judgment that ‘This or that is good,’ or against another judgment ‘That this or that is bad,’ until we have recognised what the nature of such propositions must always be. In fact, it follows from the meaning of good and bad, that such propositions are all of them, in Kant’s phrase, ‘synthetic’: they all must rest in the end upon some proposition which must be simply accepted or rejected, which cannot be logically deduced from any other proposition. This result, which follows from our first investigation, may be otherwise expressed by saying that the fundamental principles of Ethics must be self-evident. But I am anxious that this expression should not be misunderstood. The expression ‘self-evident’ means properly that the proposition so called is evident or true, by itself alone; that it is not an inference from some proposition other than itself. The expression does not mean that the proposition is true, because it is evident to you or me or all mankind, because in other words it appears to us to be true. That a proposition appears to be true can never be a valid argument that true it really is. By saying that a proposition is self-evident, we mean emphatically that its appearing so to us, is not the reason why it is true: for we mean that it has absolutely no reason. It would not be a self-evident proposition, if we could say of it: I cannot think otherwise and therefore it is true. For then its evidence or proof would not lie in itself, but in something else, namely our conviction of it. That it appears true to us may indeed be the cause of our asserting it, or the reason why we think and say that it is true: but a reason in this sense is something utterly different from a logical reason, or reason why something is true. Moreover, it is obviously not a reason of the same thing. The evidence of a proposition to us is only a reason for our holding it to be true: whereas a logical reason, or reason in the sense in which self-evident propositions have no reason, is a reason why the proposition itself must be true, not why we hold it so to be. Again that a proposition is evident to us may not only be the reason why we do think or
