The defect in most deontological theories (and this would seem to apply to Ross, Anscombe, and Nagel) is that they have no coherent rational account to give of any level of moral thought above that of the man who knows some good simple moral principles and sticks to them. He is a very admirable person; and to question his principles (at any rate in situations of stress and temptation) is indeed to 'show a corrupt mind'. But if philosophers do no more thinking than he is capable of, they will be able to give no account, either of how we are to come by these admirable principles, or of what we are to do when they conflict.
To achieve such an account, we have to adopt a 'two-level' approach. We have, that is to say, to recognize that the simple principles of the deontologist, important as they are, have their place at the level of character-formation (moral education and self-education). They are what we should be trying to inculcate into ourselves and our children if we want to stand the best chance, amid the stresses and temptations of the moral life, of doing what is for the best. Moore (who was a utilitarian) perhaps exaggerates when he says that we should never break principles which we know to be in general sound; but a utilitarian who takes his utilitarianism seriously is likely to recommend that we form in ourselves, and continue in all our actions to foster, a firm disposition to abide by the principles whose general inculcation will have, all in all, the best consequences.
(R. M. Hare, "Rules of War and Moral Reasoning," chap. 5 in Essays on Political Morality [Oxford: Clarendon Press, 1989], 45-61, at 53 [italics in original; parenthetical reference omitted; footnote omitted] [essay first published in 1972])
