In prosocial decisions, decision-makers are inherently uncertain about how their decisions impact others’ utility – we call this interpersonal uncertainty. We show that people’s response to interpersonal uncertainty shapes well-known patterns of prosocial behavior. First, using standard...

In prosocial decisions, decision-makers face interpersonal uncertainty - uncertainty about how their choices impact others' utility. We use three approaches to show how it shapes classic patterns of prosocial behavior like ingroup favoritism, merit-based fairness, and self-favoring behavior....