It is manifest, however, that this last school, if it proceeded no further than I have stated, would have failed to accomplish the task which every moralist must undertake. It is easy to understand that experience may show that certain actions are conducive to the happiness of mankind, and that these actions may in consequence be regarded as supremely excellent. The question still remains, why we are bound to perform them. If men, who believe that virtuous actions are those which experience shows to be useful to society, believe also that they are under a natural obligation to seek the happiness of others, rather than their own, when the two interests conflict, they have certainly no claim to the title of inductive moralists. They recognise a moral faculty, or natural sense of moral obligation or duty as truly as Butler or as Cudworth. And, indeed, a position very similar to this has been adopted by several intuitive moralists. Thus Hutcheson, who is the very founder in modern times of the doctrine of “a moral sense,” and who has defended the disinterested character of virtue more powerfully than perhaps any other moralist, resolved all virtue into benevolence, or the pursuit of the happiness of others; but he maintained that the excellence and obligation of benevolence are revealed to us by a “moral sense.” Hume, in like manner, pronounced utility to be the criterion and essential element of all virtue, and is so far undoubtedly a Utilitarian; but he asserted also that our pursuit of virtue is unselfish, and that it springs from a natural feeling of approbation or disapprobation distinct from reason, and produced by a peculiar sense, or taste, which rises up within us at the contemplation of virtue or of vice.(1) A similar doctrine has more recently been advocated by Mackintosh. It is supposed by many that it is a complete description of the Utilitarian system of morals, that it judges all actions and dispositions by their consequences, pronouncing them moral in proportion to their tendency to promote, immoral in proportion to their tendency to diminish, the happiness of man. But such a summary is clearly inadequate, for it deals only with one of the two questions which every moralist must answer. A theory of morals must explain not only what constitutes a duty, but also how we obtain the notion of there being such a thing as duty. It must tell us not merely what is the course of conduct we _ought_ to pursue, but also what is the meaning of this word “ought,” and from what source we derive the idea it expresses.