“Workers, Warriors and Criminals: Social Conflict in General Equilibrium ”, with Ernesto Dal Bó , July 2004.

We analyze how economy-wide forces (i.e.shocks to terms of trade, technology and endowments) affect the intensity of social conflict. We see conflict phenomena such as crime and civil war as involving resource appropriation activities. We show that not all favorable shocks to an economy will reduce conflict, even when they could make society richer. Positive shocks to labor intensive industries will diminish social conflict, while positive shocks to capital intensive industries will increase it. The key requirement is that appropriation activities be more labor intensive than the economy. Our model can explain the positive association between crime and inequality, and the curse of natural resources; it predicts that aid in kind to war-ridden societies will have perverse effects, and offers guidance on how to integrate international trade policy and peacekeeping efforts. Including appropriation activities into a canonic general equilibrium model introduces a social constraint to policy analysis. Thus, we can also account for populist optimal policies, apparently inefficient redistribution and "national development strategies".

"Political Dynasties" with Ernesto Dal Bó and Jason Snyder, May 2006

We study political dynasties in the United States Congress since its inception in 1789. We document patterns in the evolution and profile of political dynasties, study the self-perpetuation of political elites, and analyze the connection between political dynasties and political competition. We find that the percentage of dynastic legislators is decreasing over time and that dynastic legislators have been significantly more prevalent in the South, the Senate and the Democratic party. While regional and party differences have largely disappeared over time, the difference across chambers has not. We also show that the political careers of dynastic politicians differ in important ways from other legislators. We also find that increases in political competition are associated with fewer dynastic legislators. We then investigate the self-perpetuation of political elites. We find that legislators who enjoy longer tenures are significantly more likely to have relatives entering Congress later. Using instrumental variables methods, we establish that this relationship is causal: a longer period in power increases the chance that a person may start (or continue) a political dynasty. Therefore, dynastic political power is self-perpetuating in that a positive exogenous shock to a person's political power has persistent effects through posterior dynastic attainment.

"The Evolution of Cooperation in Infinitely Repeated Games: Experimental Evidence" with Guillaume Fréchette, October 2006.

We present experimental evidence on the evolution of cooperation in infinitely repeated games as subjects gain experience. We find that cooperation decreases with experience when it cannot be supported as an equilibrium outcome. More interestingly, the converse is not necessarily true: cooperation does not always increase with experience when it can be supported as an equilibrium outcome. Nor is a more stringent condition, risk dominance, sufficient for cooperation to arise. However, subjects do learn to cooperate when the payoff to cooperation and the importance of the future is high enough. These results have important implications for the theory of infinitely repeated games. While we show that cooperation may prevail in infinitely repeated games, the conditions under which it happens are more stringent than the sub-game perfect conditions usually considered.

"Institutions and Behavior: Experimental Evidence on the Effects of Democracy" with Andrew Foster and Louis Putterman, April 2007.

We present results from a novel experiment on the effect of a policy designed to encourage cooperation in a prisoner’s dilemma game. We find that the effect of this policy on the level of cooperation is greater when it was chosen democratically by the subjects than when it was exogenously imposed. This difference remains after controlling for selection (those that choose the policy may be more likely to be affected by it). We conclude that the treatment effect of policies may depend on whether they are endogenous or exogenous to the society on which they are imposed. Therefore, democratic institutions may have an effect on behavior in addition to the
effect in terms of policy choice. More generally, our findings have implications for empirical studies of treatment effects in other contexts: the effect of a treatment may depend on whether it is endogenous or exogenous.

"Love, Hate and Murder: Commitment Devices in Violent Relationships" with Anna Aizer, October 2007.

Many violent relationships are characterized by a high degree of cyclicality: women who are the victims of domestic violence often leave and return multiple times. To explain this we develop a model of time inconsistent preferences in the context of domestic violence. This time inconsistency generates a demand for commitment. We present supporting evidence that women in violent relationships display time inconsistent preferences by examining their demand for commitment devices. We find that "no-drop" policies -- which compel the prosecutor to continue with prosecution even if the victim expresses a desire to drop the charges -- result in an increase in reporting. No-drop policies also result in a decrease in the number of men murdered by intimates suggesting that some women in violent relationships move away from an extreme type of commitment device when a less costly one is offered.