Much of our ordinary cooperative activity is embedded in groups of which we are members. Groups are themselves the focus of cooperation for collective purposes, and they can help to induce cooperative behavior by their members even in essentially dyadic relationships. In the former case, when we need collective action, we might wonder whether our groups can be trusted to cooperate in accomplishing our purpose. In the latter case, we often find that our groups oversee our individual actions and induce us to be cooperative even though we could not say that the group and its members trust us. The way small communities induce their members to behave in certain cooperative or coordinative ways is through sanctions for the violation of communal norms, among the most important of which is a norm of cooperativeness within the group.

Russell Hardin, Trust and Trustworthiness, loc. 808