Utilitarianism posits that the ethical good is the greatest good for the greatest number. This moral principle implies simple aggregation of individual utilities without accounting for interpersonal comparisons. Needs and tastes may differ, however, and two problems appear paramount in determining what the greatest good actually is. The first problem is variety: How do we allow for the different needs of men and women, poor and wealthy, Christian and Taoist, and so forth? The second problem, given such variety, is interpersonal utility judgment: Who is in a position to make the comparisons necessary for maximizing the good?

Both problems received notice in classical utilitarianism. Jeremy Bentham maintained in The Rationale of Reward that utility is a simple calculus of personal pleasure and pain, so he ...