  An immense variety of views fall within this category. At one extreme is the idea that we can apprehend a priori a general principle from which we can derive particular moral claims using non-moral facts as minor premises. According to Henry Sidgwick (Sidgwick, The Methods of Ethics, 1907), we know a priori several self-evident axioms that are objectively true, including axioms of benevolence and justice, and that lead together to the conclusion that each of us ought to do what will bring about the best consequences when their value is known by the ratio of pleasure over pain in them viewed impartially. (See de Lazari-Radek &amp; Singer, 2014, for an up-to-date exposition and defense of Sidgwick’s famous work in light of current issues in moral philosophy and Sidgwick’s struggle to do justice to Egoism.) Sidgwick’s ethical theory, a form of utilitarianism, contrasts with Kant’s deontological theory, according to which we know, again a priori, that we ought to treat each person as an end, never merely as a means (Kant, Groundwork of the Metaphysic of Morals, 1785). Both imply specific moral conclusions, such as that a given promise ought to be kept, once we understand what is involved in breaking and keeping the promise, either regarding their consequences (Sidgwick) or regarding what is entailed in the will to do either act (Kant). The important point is that the derivations depend on assuming as a premise something that can be known only a priori. 