Political violence is an everyday occurence in many weakly institutionalized polities. This paper offers a unified approach for studying political violence whether it emerges as repression or civil conflict. We formulate a model where an incumbent or opposition can choose to use violence as a means of acquiring or maintaining power. We study the institutional and economic factors that determine the use of one-sided or two-sided violence (repression or civil war). The model gives way naturally to a hierarchy of violence from repression to civil war, which forms the basis for our empirical approach. Accordingly, we construct an ordered variable to explore the empirical determinants of violence. Two robust factors emerge from the data. First, economic shocks are robustly correlated with the use of violence. Second, the relationships are heterogeneous depending on political institutions. All our results are based on exploiting only the within-country variation in violence.

Abstract: Does an expansion of the population size expose nation states to a higher risk of suffering from civil conflict? Obtaining empirical evidence for a causal relationship is difficult due to reverse effects and omitted variable bias. This paper addresses causality issues by using randomly occurring drought as an instrumental variable to generate exogenous variation in population size for a panel of 37 Sub-Saharan countries over the period 1981-2004. Instrumental variable estimates yield that a five percentage point increase in population size raises the risk of civil conflict by around six percentage points.

Since World War II there have been about fifty episodes of large-scale mass killings of civilians and massive forced displacements. They were usually meticulously planned and independent of military goals. We provide a model where con‡ict onset, conflict intensity and the decision to commit mass killings are all endogenous, with two main goals: (1) to identify the key variables and situations that make mass killings more likely to occur; and (2) to distinguish conditions under which mass killings and military conflict intensity reinforce each other from situations where they are substitute modes of strategic violence. We predict that mass killings are most likely in societies with large natural resources, significant proportionality constraints for rent sharing, low productivity and low state capacity. Further, massacres are more likely in a civil than in an interstate war, as in the latter group sizes matter less for future rents. In non polarized societies there are asymmetric equilibria with only the larger group wanting to engage in massacres. In such settings the smaller

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We use new data to examine the effects of giant oilfield discoveries around the world since 1946. On average, these discoveries increase per capita oil production and oil exports by up to 50 percent. But these giant oilfield discoveries also have a dark side: they increase the incidence of internal armed conflict by about 5-8 percentage points. This increased incidence of conflict due to giant oilfield discoveries is especially high for countries that had already experienced armed conflicts or coups in the decade prior to discovery.

Abstract: What are the impacts of war on the participants, and do they vary by gender? Are excombatants damaged pariahs who threaten social stability, as some fear? Existing theory and evidence are inconclusive and focus on males. New data and a tragic natural experiment in Uganda allow us to estimate the impacts of war on both females and males, and assess how war experiences affect reintegration success. As expected, violence drives social and psychological problems, especially among females. Unexpectedly, however, most women returning from armed groups reintegrate socially and are psychologically resilient. Partly for this reason, post-conflict hostility is low. Theories that war conditions youth into violence find little support. Finally, the findings confirm a human capital view of recruitment: economic gaps are driven by time away from civilian education and labor markets. Unlike males, however, females have few civilian opportunities and so they see little adverse economic impact of recruitment. 1

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Which factors stand in the way of cooperation between countries formerly at war? We examine the role of nationalistic content of a media outlet reaching citizens of a neighboring country. We consider radio signals travelling across borders in the region that witnessed one of Europe’s deadliest conflicts since WWII: the Serbo-Croatian conflict in the Yugoslavian wars. Using survey and election data, we show that, after a decade since the end of the war, cross-border nationalistic Serbian radio triggers animosity towards Serbs in Croatia, potentially endangering peace. In particular, we find that a large fraction of Croats listen to Serbian radio (intended for Serbian listeners across the border) whenever signal is available. The residents of Croatian villages with good-quality signal of Serbian public radio are more likely to vote for extreme nationalist parties. In addition, ethnically offensive graffiti are more common in villages with Serbian radio reception. A laboratory experiment confirms that Serbian radio exposure causes an increase in anti-Serbian sentiment among Croats. Our special thanks go to Kristina Gulmac, Tihomir Zivic and to the University of Vukovar for the invaluable

Abstract: This study exploits within-state variation in drought severity to identify how insurgency during the Mexican Revolution, a major early 20th century armed conflict, im-pacted subsequent government policies and long-run economic development. Using a novel municipal-level dataset on revolutionary insurgency, the study documents that municipali-ties experiencing severe drought just prior to the Revolution were substantially more likely to have insurgent activity than municipalities where drought was less severe. Many insur-gents demanded land reform, and following the Revolution, Mexico redistributed over half of its surface area in the form of ejidos: farms comprised of individual and communal plots that were granted to a group of petitioners. Rights to ejido plots were non-transferable, renting plots was prohibited, and many decisions about the use of ejido lands had to be countersigned by politicians. Instrumental variables estimates show that municipalities with revolutionary insurgency had 22 percentage points more of their surface area redistributed as ejidos. Today, insurgent municipalities are 20 percentage points more agricultural and 6 percentage points less industrial. Incomes in insurgent municipalities are lower and al-ternations between political parties for the mayorship have been substantially less common. Overall, the results support a view of history in which relatively modest events can have highly nonlinear and persistent influences, depending on the broader societal circumstances.

This paper tests the hypothesis that democratization reduces conflict. Estimates based on a differences-in-differences design using data from the Third Wave of De-mocratization suggest that democratization has no effect on conflicts when including external interventions and conflicts for territories, but significantly and persistently reduces internal civil conflict about the control of the government. The effect sets in after democratization and appears to be persistent. The democratization scenario in terms of violence during the transition also has a significant effect on subsequent conflict for government.