In the realization of individuality there is found also the needed realization of some community of persons of which the individual is a member; and, conversely, the agent who duly satisfies the community in which he shares, by that same conduct satisfies himself.
Otherwise put, the postulate is that there is a community of persons; a good which realized by the will of one is made not private but public. It is this unity of individuals as respects the end of action, this existence of a practical common good, that makes what we call the moral order of the world.
Shakespeare has stated the postulate—
To thine ownself be true;
And it must follow, as the night the day,
Thou can'st not then be false to any man.
Its significance may be further developed by comparing it with the scientific postulate.
All science rests upon the conviction of the thorough-going and permanent unity of the world of objects known—a unity which is sometimes termed the 'uniformity of nature' or the 'reign of law'; without this conviction that objects are not mere isolated and transitory appearances, but are connected together in a system by laws or relations, science would be an impossibility. Moral experience makes for the world of practice an assumption analogous in kind to that which intellectual experience makes for the world of knowledge. And just as it is not the affair of science, as such, or even of logic (the theory of science) to justify this presupposition of science, or to do more than show its presence in intellectual experience, so it is not the business of conduct, or even of ethics (the theory of conduct) to justify what we have termed the 'ethical postulate'. In each case the further inquiry belongs to metaphysics.
XLI.
Does the End Proposed Serve as a Criterion of Conduct?