If, then, we are to regard the morality of Common Sense as a machinery of rules, habits, and sentiments, roughly and generally but not precisely or completely adapted to the production of the greatest possible happiness for sentient beings generally; and if, on the other hand, we have to accept it as the actually established machinery for attaining this end, which we cannot replace at once by any other, but can only gradually modify; it remains to consider the practical effects of the complex and balanced relation in which a scientific Utilitarian thus seems to stand to the Positive Morality of his age and country.
Generally speaking, he will clearly conform to it, and endeavour to promote its development in others. For, though the imperfection that we find in all the actual conditions of human existence—we may even say in the universe at large as judged from a human point of view—is ultimately found even in Morality itself, in so far as this is contemplated as Positive; still, practically, we are much less concerned with correcting and improving than we are with realising and enforcing it. The Utilitarian must repudiate altogether that temper of rebellion against the established morality, as something purely external and conventional, into which the reflective mind is always apt to fall when it is first convinced that the established rules are not intrinsically reasonable. He must, of course, also repudiate as superstitious that awe of it as an absolute or Divine Code which Intuitional moralists inculcate. Still, he will naturally contemplate it with reverence and wonder, as a marvellous product of nature, the result of long centuries of growth, showing in many parts the same fine adaptation of means to complex exigencies as the most elaborate structures of physical organisms exhibit: he will handle it with respectful delicacy as a mechanism, constructed of the fluid element of opinions and dispositions, by the indispensable aid of which the actual quantum of human happiness is continually being produced; a mechanism which no 'politicians or philosophers' could create, yet without which the harder and coarser machinery of Positive Law could not be permanently maintained, and the life of man would become—as Hobbes forcibly expresses it—"solitary, poor, nasty, brutish, and short."
(Henry Sidgwick, The Methods of Ethics, 7th ed. [Indianapolis: Hackett Publishing Company, 1981], bk. IV, chap. V, sec. 1, pp. 475-6 [italics in original; footnote omitted] [first published in 1907; 1st ed. published in 1874])
Note from KBJ: Unlike, say, Peter Singer, Sidgwick was respectful of commonsense morality. Singer, for example, has attacked the sanctity-of-life doctrine and the acts-and-omissions doctrine. He has argued that famine relief is a matter of justice and not, as most people think, charity. He is a progressive first and a utilitarian second. Sidgwick was a utilitarian first and a progressive second.