William MacAskill, Krister Bykvist, and Toby Ord: Moral Uncertainty: Oxford: Oxford University Press, 2020. Hardback (ISBN 978–0198722274) £ 50.00. 240 Pp.

Abstract

When epistemic limitations preclude definitive knowledge of moral facts, rational decision-making requires accounting for moral uncertainty rather than acting solely on the theory assigned the highest credence. Evaluating choices based on expected choice-worthiness implies that an agent may rationally favor an option recommended by a low-credence theory if the perceived moral stakes are sufficiently high. Facilitating such inter-theoretic comparisons requires systematic decision-theoretic mechanisms: ordinal and non-comparable frameworks can be aggregated using the Borda Rule, whereas interval-scale theories can be standardized via variance voting to equalize their structural influence. These aggregation methods address theoretical objections concerning inter-theoretic comparability and fanaticism, while primarily presupposing a cognitivist metaethics. Applying this framework significantly alters practical assessments in domains such as dietary ethics and reproductive rights. Nonetheless, this heavily formal, theory-centered model necessitates significant epistemic investment to evaluate moral theories and assign credences accurately, raising procedural questions about outsourcing practical ethics to decision-theoretic algorithms. – AI-generated abstract.