Utilitarianism claims to be a rational moral theory in at least three ways. First, it claims to give us an objective standard of morality, a way of deciding moral issues, not in the light of what each of us happens to like or dislike, but on publicly verifiable grounds. Secondly, by offering only one criterion of morality it assures consistency. If we accept a system which invokes two or more independent principles, there is always the possibility of insoluble conflict. For example, if we take our stand on the Ten Commandments, we cannot, without divine revelation, be sure that we shall not one day find ourselves in a situation in which we must break one or other of them; and our system gives us no guide as to which we ought to break. By claiming that all such conflicts can, in principle, be resolved utilitarianism satisfies the demand of our rationality that no moral problem should be insoluble.
Thirdly, by incorporating the principle that, in making our calculations of utility, each person is to count for one and no person for more than one, utilitarianism appeals to our sense of justice, and justice is the most rational of the moral virtues. For injustice in action is, as Hobbes said, like absurdity in speech, using the word 'absurd' in the sense in which it is to be found in school geometry books. To be unjust is to treat two people differently when there is no relevant difference between them, without, that is to say, any reason for differential treatment.
But alas!, our demands are not always met, and the demands of our rationality are no exception. As rational beings, we all have a powerful motive, and as philosophers we have a specially powerful motive for believing that some form of utilitarianism will turn out to be correct; so it is not surprising that more and more elaborate versions of the theory have been proposed in recent years, to be answered by more and more sophisticated refutations. As one studies the moves and counter-moves the suspicion begins to grow that no formulation acceptable to all rational men can ever be produced and that this situation may be due to some fundamental misconception of the nature of morality.
(P. H. Nowell-Smith, "Some Reflections on Utilitarianism," Canadian Journal of Philosophy 2 [June 1973]: 417-31, at 417-8 [italics in original])
