§1. The object of the present Book is to examine the method of determining reasonable conduct which has been already defined in outline under the name of Egoism: taking this term as equivalent to Egoistic Hedonism, and as implying the adoption of his own greatest happiness as the ultimate end of each individual's actions. It may be doubted whether this ought to be included among received ``methods of Ethics''; since there are strong grounds for holding that a system of morality, satisfactory to the moral consciousness of mankind in general, cannot be constructed on the basis of simple Egoism. In subsequent chapters I shall carefully discuss these reasons: at present it seems sufficient to point to the wide acceptance of the principle that it is reasonable for a man to act in the manner most conducive to his own happiness. We find it expressly admitted by leading representatives both of Intuitionism and of that Universalistic Hedonism to which I propose to restrict the name of Utilitarianism. I have already noticed that Bentham, although he puts forward the greatest happiness of the greatest number as the ``true standard of right and wrong'', yet regards it as ``right and proper'' that each individual should aim at his own greatest happiness. And Butler is equally prepared to grant ``that our ideas of happiness and misery are of all our ideas the nearest and most important to us that, though virtue or moral rectitude does indeed consist in affection to and pursuit of what is right and good as such; yet, when we sit down in a cool hour, we can neither justify to ourselves this or any other pursuit till we are convinced that it will be for our happiness, or at least not contrary to it.''
And even Clarke---notwithstanding the emphatic terms in which he has maintained that ``Virtue truly deserves to be chosen for its own sake and Vice to be avoided''---yet admits that it is ``not truly reasonable that men by adhering to Virtue should part with their lives, if thereby they eternally deprived themselves of all possibility of receiving any advantage from that adherence.''
And, generally, in the ages of Christian faith, it has been obvious and natural to hold that the realisation of virtue is essentially an enlightened and far-seeing pursuit of Happiness for the agent. Nor has this doctrine been held only by persons of a cold and calculating turn of mind: we find it urged with emphasis by so chivalrous and high-minded a preacher as Bishop Berkeley. No doubt this is only one side or element of the Christian view: the opposite doctrine, that an action done from motives of self-interest is not properly virtuous, has continually asserted itself as either openly conflicting or in some manner reconciled with the former. Still the former, though less refined and elevated, seems to have been the commoner view. Indeed, it is hardly going too far to say that common sense assumes that `interested' actions, tending to promote the agent's happiness, are prima facie reasonable: and that the onus probandi lies with those who maintain that disinterested conduct, as such, is reasonable.
But, as has been before said, in the common notions of `interest', `happiness', etc., there is a certain amount of vagueness and ambiguity: so that in order to fit these terms for the purposes of scientific discussion, we must, while retaining the main part of their signification, endeavour to make it more precise. In my judgment this result is attained if by `greatest possible Happiness' we understand the greatest attainable surplus of pleasure over pain; the two terms being used, with equally comprehensive meanings, to include respectively all kinds of agreeable and disagreeable feelings. Further, if this quantitative definition of the end be accepted, consistency requires that pleasures should be sought in proportion to their pleasantness; and therefore the less pleasant consciousness must not be preferred to the more pleasant, on the ground of any other qualities that it may possess. The distinctions of quality that Mill and others urge may still be admitted as grounds of preference, but only in so far as they can be resolved into distinctions of quantity. This is the type to which the practical reasoning that is commonly called `Egoistic' tends to conform, when we rigorously exclude all ambiguities and inconsistencies: and, it is only in this more precise form that it seems worth while to subject such reasoning to a detailed examination. We must therefore understand by an Egoist a man who when two or more courses of action are open to him, ascertains as accurately as he can the amounts of pleasure and pain that are likely to result from each, and chooses the one which he thinks will yield him the greatest surplus of pleasure over pain.