Empirical Evidence for Moral Bayesianism

Abstract

Moral Bayesianism posits that rational degrees of confidence in moral judgments exhibit a probabilistic structure analogous to degrees of belief. Evaluating this thesis empirically involves testing whether degrees of moral certitude adhere to the probability calculus axiom of finite additivity relative to degrees of belief and desire. Empirical benchmarks establish that degrees of belief satisfy finite additivity substantially more than degrees of desire, a distinction that remains robust across varying levels of practical importance. When assessed against these benchmarks across binary dilemmas, degrees of moral certitude align closely with the additive structure of beliefs while significantly diverging from desires. Furthermore, in accordance with the desire-as-belief thesis, degrees of desire in moral contexts correlate strongly with moral judgments and exhibit a corresponding shift toward finite additivity. These patterns demonstrate the descriptive validity and predictive utility of moral Bayesianism, indicating that everyday moral evaluations operate under an approximately probabilistic architecture. Consequently, these findings introduce empirical constraints that challenge non-cognitivist accounts of moral psychology while lending support to cognitivist frameworks. – AI-generated abstract.