  Some who have responded to Castañeda, such as Zellner (1972: 125), took (U) not only to be a commitment of utilitarianism, but a formulation of act-utilitarianism itself. Now, here’s the supposed problem. According to Castañeda, (ODC) and (U) generate contradictory prescriptions. To see why he believed this, suppose that an agent S’s performing the conjunctive act-set \(\langle A \lamp B\rangle\) brings about a greater balance of good over bad than any alternative act-set (singleton or plural) that S can perform. It is supposed to follow from (U) that S is obligated to perform \(\langle A \lamp B\rangle\). Now, given (ODC), it follows that S is obligated to perform \(\langle A\rangle\) and that S is obligated to perform \(\langle B\rangle\). But, Castañeda claims, given (U), performing \(\langle A\rangle\) would result in more net good than performing any alternative, including \(\langle B\rangle\). Moreover, given (U), performing \(\langle B\rangle\) would also result in more net good than performing any alternative, including \(\langle A\rangle\). Hence the supposed contradiction. Performing \(\langle A\rangle\) cannot result in both more good and less good than performing \(\langle B\rangle\). This consequence may be illustrated with an example, drawn from Westphal (1972: 83–84). 