Love demands, as every interest demands, that it should dominate life completely. And, in a world where there is too much hate, the judgment of many earnest moralists is overwhelmed by the charms of love; and there are those who come to accept it at its own valuation and are thus led to assert that people have an obligation to increase the collective total of all value in the universe. But sound reason denies that love is the whole duty of man. Its validity is limited by other moral imperatives. Two of these are the interests in nourishment and in gustatory pleasure. These are selfish; but they are, within reason, legitimate, important, and usually essential elements in a good life. That is, they contribute to increasing, in the long run, the quantity of satisfaction which an individual experiences.
The interests in nourishment and in gustatory pleasure lead man to kill and eat cattle, fish, and fowl. This cuts down on the long-range satisfactions of the cattle, the fish, and the fowl. But enlightened public opinion in human society approves of man's carnivorous behavior. And I believe that in most cases man is morally justified in thus reducing the satisfactions of the food animals. Anyone who loves little lambs in a personal way more than he loves lamb chops in a gustatory way ought to forego the latter delicacies. But few people do this. The moral issue, when a man eats lamb chops, is not: Does he gain more value than the lambs have lost by dying so young? The issue is: Does he gain more value than he would experience if he let them live? Letting them live will satisfy whatever personal affection he has for them. And eating them will frustrate this love. An accurate quantitative comparison of the value he gains with that which the lamb loses is really impossible. If a man's duty depended on that, he never would know what his duty was. But an accurate quantitative comparison of how he feels about eating them and about letting them live is made every time he chooses between these alternatives. And his choice is right from his point of view, in case it and its consequences are more satisfactory to him in the long run than the alternative would be.
Most people eat lamb chops, and their consciences are clear on this score when they demand that slaughter-houses shall kill food animals as painlessly as possible. Moreover, very few ever feel the need of taking active steps to enforce this demand.
Some will say that all true values which have any moral significance are confined to humanity and that reducing the satisfactions of food animals is not really evil. But such an argument is just another expression of man's ruthlessness toward lower organisms which he has in his power. He often ignores their values and rides roughshod over them. If an animal's foot is crushed, that is bad for the animal, just as, if a man's foot is crushed, that is bad for the man. Good and bad, value and disvalue, apply to all conscious organisms which experience satisfaction and dissatisfaction. Whoever deliberately lowers the long-range satisfaction in another conscious being does a wrong to it. Man commits many wrongs against the food animals, but he is usually right, from his own point of view, in doing so.
(Gardner Williams, "The Moral Insignificance of the Total of All Value," Ethics 55 [April 1945]: 216-21, at 219-20 [italics in original])