Inference of trustworthiness from intuitive moral judgments

Moral judgments play a critical role in motivating and enforcing human cooperation, and research on the proximate mechanisms of moral judgments highlights the importance of intuitive, automatic processes in forming such judgments. Intuitive moral judgments often share characteristics with deontological theories in normative ethics, which argue that certain acts (such as killing) are absolutely wrong, regardless of their consequences. Why do moral intuitions typically follow deontological prescriptions, as opposed to those of other ethical theories? Here, we test a functional explanation for this phenomenon by investigating whether agents who express deontological moral judgments are more valued as social partners. Across 5 studies, we show that people who make characteristically deontological judgments are preferred as social partners, perceived as more moral and trustworthy, and are trusted more in economic games. These findings provide empirical support for a partner choice account of moral intuitions whereby typically deontological judgments confer an adaptive function by increasing a person’s likelihood of being chosen as a cooperation partner. Therefore, deontological moral intuitions may represent an evolutionarily prescribed prior that was selected for through partner choice mechanisms.