Correspondence

Abstract

Act utilitarianism requires the maximization of expected utility, calculated by multiplying the magnitude of potential benefits or costs by their probability of occurrence. While it is frequently suggested that infinitesimal probabilities should be excluded from these calculations, such an exclusion leads to the erroneous conclusion that individuals have no rational basis for participating in large-scale collective actions, such as voting or contributing to public goods. In high-stakes scenarios involving large populations, the minute probability of an individual act proving decisive is mathematically offset by the scale of the aggregate impact. For instance, the expected utility of a single vote remains positive if the potential benefit to a nation is sufficiently large, even if the chance of breaking a tie is statistically remote. A distinction must be drawn between the scale of the stakes and the scale of the probability; whereas a tiny risk of minor harm may be negligible, a tiny risk of catastrophic harm or widespread benefit necessitates consideration. Consequently, the rationality of an act depends on the total sum of expected outcomes, where the large number of affected persons compensates for the smallness of the individual chance or the imperceptibility of the individual benefit. – AI-generated abstract.