Moral Decision-Making Under Uncertainty

Abstract

This survey examines philosophical debates concerning moral decision-making under uncertainty, where agents lack complete knowledge of empirical facts or fundamental moral principles. The authors contrast objective (“fact-relative”) evaluations with subjective (“belief-relative”) and prospective (“evidence-relative”) standards of permissibility, illustrating why principles formulated for conditions of certainty cannot be straightforwardly applied to risky environments. While expected utility theory provides the orthodox framework for normative decisions under uncertainty, its application to ethics encounters severe obstacles. Within consequentialist frameworks, agents face the problem of “cluelessness” stemming from the unpredictable, long-term, and potentially indeterminate effects of ordinary acts. For non-consequentialist theories, accommodating agent-centred constraints under risk exposes difficulties with probability thresholds, risk agglomeration, and attempts to represent deontological duties through bounded or lexicographic utility functions. The entry further explores decision-making under fundamental moral uncertainty, contrasting externalism with approaches such as “My Favorite Theory” and maximizing expected choiceworthiness, while evaluating persistent difficulties including intertheoretic value comparisons, structural theory diversity, and higher-order regress. Finally, the authors analyze the problem of fanaticism—where deliberation is overwhelmed by tiny probabilities of astronomical moral value or extreme harms—and survey the respective structural costs of accepting fanatical implications versus attempting to evade them via bounded utility functions or small-probability discounting. – AI-generated abstract.