In several common-value environments (e.g., auctions or elections), players should make informational inferences from opponents' strategies under certain hypothetical events (e.g., winning the auction or being pivotal). We design a voting experiment that identifies whether subjects make these...

The focus of this paper is the endogenous formation of peer groups. In our model agents choose peers before making contributions to public projects, and they differ in how much they value one project relative to another. Thus, the group's preference composition affects the type of contributions...

We consider the spread of a harmful state through a population divided into two groups. Interaction patterns capture the full spectrum of assortativity possibilities. We show that a central planner who aims for eradication optimally either divides equally the resources across groups, or...

Behavioral economics has shaken the view that individuals have well-defined, consistent and stable preferences. This raises a challenge for welfare economics, which takes as a key postulate that individual preferences should be respected. We argue, in agreement with Bernheim (2009) and Bernheim...

Economists are increasingly interested in how group membership affects individual behavior. The standard method assigns individuals to "minimal" groups, i.e. arbitrary labels, in a lab. But real group often involve social interactions leading to social ties between group members. Our experiments...

We provide a generalization of Harsanyi's (1955) aggregation theorem to the case of incomplete preferences at the individual and social level. Individuals and society have possibly incomplete expected utility preferences that are represented by sets of expected utility functions. Under Pareto...

We study the role of intergroup mobility in the emergence of conflict. Two groups compete for the right to allocate society's resources. We allow for costly intergroup mobility. The winning group offers an allocation, which the opposition can accept or reject, and wage conflict. Agents can also...

We study optimal contracting in team settings where agents have many opportunities to shirk, task-level monitoring is needed to provide useful incentives, and it is difficult to write individual performance into formal contracts. Incentives are provided informally, using wasteful sanctions like...

One explanation of altruism is that it arises from "mentalizing", the process of understanding the mental states of others. Another is based on sexual selection: altruism is a costly signal of good genes. This paper shows that these two arguments are stronger together in that altruists who can...

We present a model in which an agent takes actions to affect her reputation with two audiences with diverse preferences. This contrasts with standard reputation models that consider a homogeneous audience. A new aspect that arises is that different audiences may observe outcomes commonly or...