Ethics is a subject about which there has been and still is an immense amount of difference of opinion, in spite of all the time and labour which have been devoted to the study of it. There are indeed certain matters about which there is not much disagreement. Almost everybody is agreed that certain kinds of actions ought, as a general rule, to be avoided and that under certain circumstances, which constantly recur, it is, as a general rule, better to act in certain specified ways rather than in others. There is, moreover, a pretty general agreement, with regard to certain things which happen in the world, that it would be better if they never happened, or, at least, did not happen so often as they do and with regard to others, that it would be better if they happened more often than they do. But on many questions, even of this kind, there is great diversity of opinion. Actions which some philosophers hold to be generally wrong, others hold to be generally right, and occurrences which some hold to be evils, others hold to be goods. And when we come to more fundamental questions the difference of opinion is even more marked. Ethical philosophers have, in fact, been largely concerned, not with laying down rules to the effect that certain ways of acting are generally or always right, and others generally or always wrong, nor yet with giving lists of things which are good and others which are evil, but with trying to answer more general and fundamental questions such as the following. What, after all, is it that we mean to say of an action when we say that it is right or ought to be done? And what is it that we mean to say of a state of things when we say that it is good or bad? Can we discover any general characteristic, which belongs in common to absolutely all right actions, no matter how different they may be in other respects?