Marianna A. Klochko, Peter C. Ordeshook

Within the rational choice paradigm, the usual way of understanding the emergence and sustainability of cooperation - of how people overcome the imperatives of the motives illustrated by the Prisoners' Dilemma - is conceptualizing individual choice as part of some ongoing social process. In addition to admitting a consideration of such things as learning and imitation, the formal acknowledgment that social processes are dynamic allows us to establish the existence of a class of equilibria that are not normally present in more limited (myopic or static) representations. Specifically, defectors from cooperation 'today' can be punished 'tomorrow' by those they injure or with whom they interact in the future and who act on the basis of reputations earned from earlier choices, while non-defection can be rewarded subsequently by allowing a person to share in the social gains from cooperation. Put simply, by expanding the set of strategies available to people, conceptualizing social processes as ongoing and dynamic expands the set of equilibria in our analyses to include cooperative as well as non-cooperative outcomes.