The emergence and institutionalization of cooperation in sizable groups without reciprocity receives considerable … toward global cooperation, but with severe losses of cultural diversity and tolerance. Cooperation in such regimes also … proves to be vulnerable to defection. Between, there is a space displaying relatively stable and widespread cooperation with …

Surprisingly high levels of within-group cooperation are observed in conflict situations. Experiments confirm that … external threats lead to higher cooperation. The psychological literature suggests proximate explanations in the form of group … which cooperation is a rational response to an external threat. In the model, groups vary in their willingness to help each …

cooperation through two mechanisms. First, groups differ in the benefits they receive from cooperation. This affects which groups … can commit to cooperate. Second, a nation may selectively withhold cooperation from one group to influence the domestic … under different institutional rules into a prisoner’s dilemma model of international cooperation, the theory generates …

cooperative arrangements (i.e., they refuse any future cooperation as long as the responsible incumbent remains in office), then … citizens remove leaders caught cheating, providing the cost of doing so is less than the value of the cooperation foregone. For … leaders can credibly commit to deeper and more reliable cooperation. The authors derive hypotheses about the patterns of …