It will be noticed that the possibility of such necessary principles is supplied, without going outside the limits of an empirical view of the world, by the peculiar nature of the fact on which they rest. It is of course true that if human nature were to change fundamentally, the principles stating what is now necessary to its satisfaction would no longer hold. We have to start with man's constitution as we find it, empirical and contingent. But this does not interfere with the possibility of real principles dealing with the ethically best, because 'best' is for us a word explicitly relating to man as he is. And we are freed from the uncertainty of mere empiricism, simply because our supposed necessity attaches not to a generalization of events and instances, but to the necessary connection between a want or group of wants, and the known conditions of their satisfaction. Granting both the existence of desire, and the world in which it tries to get expression and both these things are facts that are practically assured—we can anticipate further experience, and say generally, not only that men have commonly done so and so, but that so and so must be done. And the necessity remains whether or not men have done this in the past. This is, to be sure, in the end hypothetical necessity only; but since none of us have any vital interest in inquiring what we should need to do if we were apes or angels, the principles practically, though not theoretically, remain absolute.
Before inquiring, however, into the general source and nature of such principles, I should like to go back, from a slightly different standpoint, to the basic fact which principles of guidance presuppose. In scientific language this fact is, again, the biological organism and its mechanism of instinct. These however are not the terms in which life presents itself to the natural man while he is actually engaged in living it; and it will be useful, in order to avoid ambiguities later on, to ask what is the translation of this scientific fact into more ordinary human discourse. The value of dealing with this preliminary definition first, lies in a temptation on the part of ethical philosophies to confuse the question of fact with that of ethical norm or standard, and to suppose that they are furnishing a guide to life when
