When considering engaging in conflict to secure control of a resource, a group needs to predict the amount of post-conflict leakage due to infiltration by members of losing groups. We use this insight to explain why conflict often takes place along ethnic lines, why some ethnic groups are more...

We present a theory of ethnic conflict in which coalitions formed along ethnic lines compete for the economy’s resources. The role of ethnicity is to enforce coalition membership: in ethnically homogeneous societies members of the losing coalition can defect to the winners at low cost, and...

Institutions that serve the interests of an elite are often cited as an important reason for poor economic performance. This paper builds a model of institutions that allocate resources and power to maximize the payoff of an elite, but where any group that exerts sufficient fighting effort can...

While a large social-choice-theoretic literature discusses the aggregation of individual judgments into collective ones, there is relatively little formal work on the transformation of individual judgments in group deliberation. I develop a model of judgment transformation and prove a baseline...

If a group is modelled as a single Bayesian agent, what should its beliefs be? I propose an axiomatic model that connects group beliefs to beliefs of the group members. The group members may have different information, different prior beliefs and even different domains (algebras) within which...

I examine decentralization through the lens of the local dynamics that it unleashes. The national effects of decentralization are simply the sum of its local-level effects. Hence to understand decentralization we must first understand how local government works. This paper proposes a theory of...

In the framework of judgment aggregation, we assume that some formulas of the agenda are singled out as premisses, and that both Independence (formula-wise aggregation) and Unanimity Preservation hold for them. Whether premiss-based aggregation thus defined is compatible with conclusion-based...

There is a lot of evidence that identity matters for behavior. There is a widespread belief that societies will function better if they manage to establish a common sense of identity among the population. And there are also contemporary fears that this common identity is threatened in several...

In this paper I analyze the effect of the transparency of the decision making process in committees on the decisions that are eventually taken. I focus on committees whose members are motivated by career concerns, so that each member tries to enhance his own reputation. When the decision making...