Joseph J. Ruggiero

The preventive motive for war arises because states cannot commit to limit the use of their growing power. This commitment problem can lead to war when there are not enough resources available today to compensate the declining state for their expected losses. In this article, we show how capital markets affect preventive war incentives by introducing a profit-maximizing bond market to the canonical bargaining model of war. We find that the nature of the power shift and fundamentals of the market for debt interact to determine when a preventive motive is more likely to lead to war. Two main results show that (1) less probable but more extreme power shifts are most dangerous and (2) unlike the direct effect of interest rates on the cost of war, higher interest on sovereign debt makes war more likely. We present evidence for the latter effect by extending Lemke's (2003) study of preventive war for major-power dyads between 1816 and 1992.

Maintaining peace with adversaries can be costly, yet conflict models depict cooperation as a costless byproduct of not fighting. This article provides a formal model where peace may be costly and countries compete over bargaining surplus. Against conventional wisdom, repeated interactions of patient countries can destabilize peace without power shifts, as countries may prefer to "rip off the bandage." The likelihood of war depends on fundamentals of the international order, including outcome persistence and the severity of competition. Even when cooperation is mutually beneficial, wars are inevitable in the long run due to a coordination problem induced by costly peace. Competition over favorable settlements does not directly instigate attacks, but it reduces the gains from peace while counterintuitively making war less likely. The article offers new systemic explanations for war, highlights the importance of institutional design in conflict resolution, and sheds light on which international orders fare well over time.

Social connections matter for vote buying, yet most analyses do not specify the nature of interdependence between actors explicitly. We provide a formal model of elections in which candidates may offer private transfers to policy-motivated voters connected on a social network. Investigation of deep parameters governing social structure allows for comparison across societies without the need to consider specific realizations. In equilibrium, transfers are determined primarily by group fractionalization and homophily, with density mattering only indirectly. Inequalities are driven by disproportionate targeting of minorities. Additionally, we consider heterogeneous information between candidates, clarifying the main role of density as a source of more precise information for candidates and demonstrating that homophily can endogenously generate in-group favoritism. These results highlight the importance of social structure, moving beyond the existing focus on individual targeting.

Why do some conflicts escalate to global war while others stay contained? I provide a formal model of conflict with many countries located on an economic network. Countries may attack an adversary of their choosing and, if war breaks out, the remaining countries choose whether to join the fight. The distribution of power and globalization can interact to affect the system's propensity for conflict in various ways, motivating quantitative analysis. By connecting the theoretical model to data on international disputes, I estimate deep structural parameters governing country preferences, including the underlying economic network. Lastly, I perform counterfactual analysis for World War I, the Russian invasion of Ukraine, and a potential China-Taiwan conflict.