ABSTRACT
John Locke did not publish a treatise on ethics, but he did write one, the manuscript from the 1660s originally edited by W. von Leyden as Essays on the Law of Nature (Locke 1954). The works which did appear under his imprimatur include a good deal of material on morality, as do his notebooks, correspondence and other manuscripts. There is no doubt that Locke had an interest in questions of moral philosophy throughout his career. Further, we know from James Tyrrell that An Essay concerning Human Understanding was inspired by a discussion of ‘the Principles of morality, and reveald Religion’. 1 And throughout the Essay our ability to know our moral duties is contrasted with our need to rely on probable opinion when it comes to the physical world. Does Locke's interest in morality issue in a theory of morality? He may, of course, have developed more than one theory (philosophers sometimes change their thoughts); the natural law theory of his youth and something different in his mature writings. Locke, however, continues to refer to the moral law of nature; notably in the ‘Second Treatise of Government’, but also in A Paraphrase and Notes on the Epistles of St Paul, the last work that he prepared for the press. Locke's moral theory, so far as he has one, would then be some version of natural law theory. This is not to say his ideas on morality stayed exactly as they were when he wrote the Essays on the Law of Nature, only that he does not repudiate his early work. If, on the other hand, what he has to say in his published works is inconsistent with natural law theory he does not have a moral theory.
