An argument for utilitarianism: A defence

Abstract

Utilitarianism can be derived from the combination of the Weak Majority Preference Principle (WMP) and the reality of finite sensibility. WMP posits that if at least half of a population prefers state $x$ to state $y$ while no individual prefers $y$ to $x$, then $x$ is socially preferable. Because human beings possess finite sensibility, they cannot distinguish infinitesimal changes in utility. Consequently, a social state remains indifferent when half of a population experiences a just-unnoticeable improvement in utility while the other half experiences a just-unnoticeable decline. By applying the transitivity of exact social indifference, it follows that the utility of any individual can be traded against that of another, leading to a social welfare function that maximizes the unweighted sum of individual utilities. This derivation remains robust against claims that finite sensibility necessitates intransitive social preferences, as the indifferences generated by WMP are logically exact. Furthermore, using just-noticeable differences as a standard unit for interpersonal comparisons addresses common objections regarding income inequality and the capacity for enjoyment. This utilitarian framework offers a more consistent ethical basis than the Rawlsian Maximin Principle, which risks requiring disproportionate sacrifices from the majority for negligible gains for the worst-off. – AI-generated abstract.