Even in this case, however, if it led to the adoption of the end in question, it must be borne in mind that the postulate would be implied that the true ethical end must be able to yield a consistent and harmonious system of rules for practical life. Without altogether denying this postulate, it yet seems to me that it stands in need of qualification. For in different circumstances, and at different stages of individual and social development, the application of the same ethical end may naturally produce different and conflicting courses of conduct. We must not start with any such assumption as that the rationality of the end consists in some sort of mathematical equality which ignores alike the different environment with which one age and another surround different generations, and the different functions which one individual and another have to perform in the social whole. We must leave open the possibility that what is right now may be wrong in another age; we must remember that everybody may not count for one, and that some people may count for more than one; we must admit that we may have sometimes to do to others what we would not that others should do to us. The only consistency we have a right to demand must leave room for such a variety of different conditions as to be, by itself, a very insecure guide. From the difficulty of complying with the above conditions, it seems practically impossible for the criticism of ethical methods to decide the question of the ethical end. Even if the application to conduct of every important end has been taken account of, we are met with the difficulty that two or more mutually antagonistic though self-consistent practical codes may probably have been developed, while we are not even justified in assuming that inability to yield a system which will fit the complex circumstances of life in a perfectly harmonious manner is sufficient ground for rejecting an end shown in some other way to be reasonable. [Sidenote: (β) distinct from moral psychology and sociology.]