Abstract

I begin, in section 1, with a presentation of the Interpersonal Addition Theorem. The theorem, due to John Broome (1991), is a re-formulation of the classical result by Harsanyi (1955). It implies that, given some seemingly mild assumptions, the overall utility of an uncertain prospect can be seen as the sum of its individual utilities. In sections 1 and 2, I discuss the theorem's connection with utilitarianism and in particular consider its implications for the Priority View, according to which benefits to the worse off count for more, in terms of overall utility, than comparable benefits to the better off (cf. Parfit 1995 [1991]). Broome (1991) and Klint Jensen (1996) have argued that, in view of the Interpersonal Addition Theorem, the Priority View should be rejected for measurement-theoretical reasons. Therefore, it cannot be seen as a plausible competitor to utilitarianism (cf. section 1). I will suggest, however, that a proponent of the Priority View would be well-advised, on independent grounds, to reject one of the basic assumptions on which the Addition Theorem is based. I have in mind the so-called Principle of Personal Good for uncertain prospects (cf. sections 4 and 5). If the theorem is disarmed in this way, then, as a side benefit, the Priority View will avoid the afore-mentioned problems with measurement.