Inclusive groups can avoid the tragedy of the commons.

The public goods game is a famous example illustrating the tragedy of the commons (Hardin in Science 162:1243-1248, 1968). In this game cooperating individuals contribute to a pool, which in turn is distributed to all members of the group, including defectors who reap the same rewards as cooperators without having made a contribution before. The question is now, how to incentivize group members to all cooperate as it maximizes the common good.