Recent findings in evolutionary psychology explain how moral disciplining is connected to the need for collective action. Morals are strict in societies affected by war or perceived collective danger, but loose where peace and security prevail. This theory supplements the moral disciplining theory by providing an evolutionary explanation for the postulated link between puritanism and the need for cooperation.

A collective action problem exists not only in offensive warfare, but also in defensive situations. The collective action problem is dealt with in the same way in offensive and defensive warfare: by strong leadership, discipline, rewards and punishments, strong group identification, strict religiosity, and intolerance of deviants. This behavior is explained in terms of evolutionary psychology.

A group in intergroup conflict needs to overcome the collective action problem in order to defend itself against an external enemy. This leads to increasing complexity that cannot be adequately covered by just scaling up the model of intragroup conflicts. Research on cultural evolution and evolutionary psychology shows that external conflict has profound effects on group organization.