Justice, utility, and interpersonal comparisons

Abstract

One of the most common objections against utilitarianism is that it cannot account for the claims of distributive justice. This objection can be answered by appeal to the principle of Diminishing Marginal Utility (DMU), which says that the value of a given portion of a commodity tends to increase as a person's supply of the commodity decreases. DMU implies that, other things equal, the way to maximize the value of a commodity is to distribute it equally. Some economists have objected to DMU on the ground that it presupposes interpersonal comparisons of utility, but the arguments which they have advanced against the objectivity of such comparisons are unsound. Moreover, the interpersonal comparisons presupposed by DMU are ordinal, rather than cardinal, and there are reasons for believing that ordinal comparisons, at least, do have an objective basis.