Population ethics: the challenge of future generations

Abstract

Population ethics faces fundamental challenges in ranking outcomes where both the number of people and their welfare levels vary. Analysis of existing theories—including total and average utilitarianism, variable value principles, critical-level theories, and person-affecting views—demonstrates that each entails counterintuitive results. These include the repugnant conclusion, where a vast population of lives barely worth living is judged superior to a smaller population of high-quality lives, and the sadistic conclusion, where adding miserable lives is preferred to adding happy ones. These difficulties extend beyond welfarist frameworks to encompass egalitarian and priority-based moralities. Central to this work is the formal proof of several impossibility theorems, which establish that no population axiology or morality can simultaneously satisfy a small set of intuitively compelling adequacy conditions. These conditions involve basic assumptions regarding dominance, inequality aversion, non-sadism, and the weighing of quality against quantity. The logical inconsistency among these minimal conditions suggests that considered moral beliefs regarding future generations are mutually incompatible. Consequently, the impossibility results challenge the possibility of a fully justified moral theory, forcing a choice between rejecting deeply held moral intuitions, accepting moral skepticism, or fundamentally reconsidering the methodology of ethical justification. – AI-generated abstract.