Social identity has been shown to successfully enhance cooperation and effort in cooperation and coordination games. Little is known about the causal effect of social identity on the propensity to engage in group conflict. In this paper we explore theoretically and experimentally whether social...

Due to incomplete contracts, efficiency of an organization depends on willingness of individuals to take non-selfish actions, such as cooperating when there is no incentive to do so or punishing inefficient actions by others. Organizations also constitute a social boundary, or group. We...

Economists commonly use the Edgeworth box to illustrate the ability of exchange to generate gains from trade. In contrast to this framework of dyadic exchange, we explore triadic forms of exchange where margins of coercion are also present. In the presence of triadic exchange, market...

Democratic societies are challenged by various violent and organized groups, be they terrorists, gangs or organized hooligans. In exchange for offering an identity, leaders in such groups typically require members to be violent. We introduce a simple model to capture these stylized facts, and...

The present paper analyzes the occurrence of the group-size paradox in situations in which groups compete for rents, allowing for degrees of rivalness of the rent among group members. We provide two intuitive criteria which for groups with homogenous valuations of the rent determine whether...

In this paper we present a conceptual framework linking cultural heterogeneity to inter-group conflict. When conflict is about control of public goods, more heterogeneous groups are expected to fight more with each other. In contrast, when conflict is about rival goods, more similar groups are...

Our model consists of two groups. Group 1 holds political power and Group 2 threatens this power. Group 1 decreases the probability of its upheaval by co-opting some agents from Group 2 into a more benign third group. Improvements in the upheaval technology lead to fewer but better co-optation...

Recent theoretical advances and quasi-experimental evidence from modern conflict areas suggest that intergroup conflict and ostracism play a pivotal role in the evolution of cooperation. However, relatively little is known about the role of intergroup conflict and ostracism on group formation...

The present paper analyzes situations in which groups compete for rents. A major result in the literature has been that there are both cases where larger groups have advantages and cases where they have disadvantages. The paper provides two intuitive criteria which for groups with homogenous...

This paper surveys some of the strategic aspects that emerge if players fight in an alliance against an enemy. The survey includes the free-rider problem and the hold-up problem that emerges in the baseline model, the role of supermodularity in alliance members' effort contributions, the role of...