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 processes, but does not explain how these processes...

We examine why heterogenous communities may fail to provide public goods. Current work characterizes sanctioning free-riders as an under-supplied public good. We argue that often free-riders can be punished by the coordinated action of a group. This punishment can be profitable, and need not be...

Field studies of conflict report cycles of mutual revenge between groups, often linked to perceptions of intergroup injustice. We test the hypothesis that people are predisposed to reciprocate against groups. In a computerized laboratory experiment, subjects who were harmed by a partner’s...

In the tight budgetary conditions following the 2008 financial crisis, governments have proposed saving money by reforming public services. This paper argues that tight budget constraints make reform harder by introducing an information problem. Governments are uncertain about bureaucratic...

Some social institutions reveal participants’ behavior in the aggregate, while concealing the identities of the participants. For example, individual church donations may be kept anonymous, while the total amount raised is publicized. This presents a puzzle in light of recent evidence that...

We report an experiment on the Probabilistic Serial (PS) mechanism for allocating indivisible goods. The PS mechanism, a recently discovered alternative to the widely used Random Serial Dictatorship mechanism, has attractive fairness and efficiency properties if people report their preferences...

We report an experiment on the Probabilistic Serial (PS) mechanism for allocating indivisible goods. The PS mechanism, a recently discovered alternative to the widely used Random Serial Dictatorship mechanism, has attractive fairness and efficiency properties if people report their preferences...

In public goods environments, the threat to punish non-contributors may increase contributions. However, this threat may make players' contributions less informative about their true social preferences. This lack of information may lead to lower contributions after the threat disappears, as we...

All rulers face political competition, both from rivals within their state, and from other states to which their subjects may exit. In a simple model, both kinds of competition are substitutes. Internal competition (democracy) bene?ts citizens by allowing them to replace rent-seeking rulers. But...

Religion and ritual have been characterized as costly ways for conditional cooperators to signal their type, and thus identify and interact with one another. But an effective signal may be prohibitively expensive: if the cost of participation is too small, freeriders may send the signal and...