The evolution of norms

Social norms that induce us to reward or punish people not for what they di d to us but for what they did to other members of one's group have long bee n thought as sine qua non sociological and thus impossible to explain in te rms of rational choice. This article shows how social norms can be deductiv ely derived from principles of (boundedly) rational choice as mechanisms th at are necessary to stabilize behaviors in a large class of evolutionary ga mes.