The aim of this essay is to provide a compendious survey of moral philosophy in English since about the beginning of the present century. Fortunately, the tale that thus falls to be told is not in outline excessively complex, and can be seen as a quite intelligible sequence of distinguishable episodes. The major stages on the road are three in number. There is, first, Intuitionism, to be considered here as represented by G. E. Moore (Principia Ethica, 1903), H. A. Prichard (Moral Obligation, published posthumously in 1949), and W. D. Ross (The Right and the Good, 1930, and Foundations of Ethics, 1939). Second, in somewhat violent reaction to the undoubted shortcomings of that style of ethics, we have Emotivism; and here the chief spokesman is C. L. Stevenson (Ethics and Language, 1944). And third, as an amendment of and an advance from Emotivism, we shall consider what may be called, and often is called, Prescriptivism, whose most lucid, persuasive, and original exponent is R. M. Hare (The Language of Morals, 1952, and Freedom and Reason, 1963). Other authors and other works, of course, will be mentioned in their places; but the main plot is determined by these three doctrines and their leading advocates.