Brink's and Pietroski's obligation execution principle

Abstract

(OE) Oa & (P == a) D 0-3. ('O' stands for 'ought to be done' or 'is obligatory', and '=-' stands for some sort of counterfactual implication.) According to Brink, who uses (OE) as an essential premiss in two arguments against the existence of moral dilemmas, (OE) 'seem[s] to be [a] fundamental or uncontroversial [principle] in our moral reasoning'. ([1], p. 237) Pietroski claims that (OE) supports the prescriptions yielded by a certain 'actualistic' principle of obligation, suggested by Frank Jackson and Robert Pargetter [3], henceforth 'J&P'. But (OE) is not valid according to J&P's actualism. Hence, it cannot be invoked to defend this theory. Moreover, the truth of (OE) is very doubtful, regardless of whether we accept J&P's principle. According to J&P, an action a ought to be done if and only if what the agent would do if she were to do a is better than what she would do if she were not to do a. To illustrate this thesis J&P use the case of Professor Procrastinate, who is asked to review a book. The best he can do is to agree and then write the review (do a& b). The second best is to decline (do --a), while the worst he can do is to agree and then not write the review (do a &-b). If Procrastinate were to agree, he would keep putting the task off and never get around to writing the review. That is, if Procrastinate were not to do --a, he would do a&-4b, which is worse than --a. Hence J&P's principle yields