Several years ago I came across a marvelous little paper in which Hector-Neri Castaneda shows that standard versions of act utilitarian l ism are formally incoherent. I was intrigued by his argument. It had long seemed to me that I had a firm grasp on act utilitarianism. Indeed, it had often seemed to me that it was the clearest and most attractive of normative theories. Yet here was a simple and relatively uncontrover sial argument that showed, with only some trivial assumptions, that the doctrine is virtually unintelligible. The gist of Castaneda's argument is this: suppose we understand act utilitarianism to be the view that an act is obligatory if and only if its utility exceeds that of each alternative. Suppose it is obligatory for a certain person to perform an act with two parts - we can call it 'A & B'. Then, obviously enough, it is also obligatory for this person to perform the parts, A and B. If act utilitarianism were true, we appar ently could infer that the utility of A & B is higher than that of A, and higher than that of B (because A & B is obligatory, and the other acts are alternatives to A & B).

Inhalt
One/Absolute Moral Obligation.- 1. Utilitarian Foundations.- 2. A Theory of Moral Obligation.- 3. Moral Objections to MO.- Two/Iffy Oughts.- 4. Basic Iffy Oughts.- 5 Hypothetical Imperatives.- 6. Defeasible Commitment and Prima Facie Obligation.- Three/Extensions.- 7. Individual Obligation and Group Welfare.- 8. What Ought to be.- 9. Conflicts of Obligation.- 10. Conclusions.- Notes.- Index of Names.- Index of Subjects.