Standard economic explanations of good conduct in trade rely almostexclusively on future-directed extrinsic motivations induced by materialincentives. But intrinsic motives to behave trustworthy and to punishuntrustworthiness do support trade. In our model, intrinsically motivatedplayers are...

Social institutions regulating group conduct have been regarded as necessaryfor human cooperation to transcend family bonds. However, manystudies in economics and biology indicate that reciprocity based on repeatedinteraction suffices to establish cooperation with non-kin. We shedlight on the...