How do individual agents enact the institutions that govern collective behavior in a social situation? How do individuals come to share self-enforcing expectations about collective behavior, so that societal rules and constraints have an effect on individual choice? Conventional accounts, such as contract and evolutionary theories or the analysis of conventions and social conflict, cannot explain the origins of social institutions because they do not address the origins of shared and self-enforcing expectations about collective behavior in a social situation. I analyze two separate stages of institutionalization. First, agents must imagine collective intentionality, so that an 'imagined institution' entailing a symbolic representation of collective behavior becomes common knowledge. Second, they must 'enact' it through shared and self-enforcing expectations on the path of play. In my model, the agents are goal-oriented, so the process is strategic throughout.
