An influential conventional wisdom holds that civil wars proliferated rapidly with the end of the Cold War and that the root cause of many or most of these has been ethnic nationalism. We show that the current prevalence of internal war is mainly the result of a steady accumulation of protracted conflicts since the 50s and 60s rather than a sudden change associated with a new, post-Cold War international system. We also find that after controlling for per capita incomes and growth rates, more ethnically or religiously diverse countries have been no more likely to experience significant civil war in this period. We argue for understanding civil war in this period in terms of insurgency or rural guerrilla warfare, a particular form of military practice that can be harnessed to diverse political agendas, including but not limited to ethnic nationalism. The factors that explain which countries have been at risk for civil war are not their ethnic or religious characteristics but rather the conditions that favor insurgency. These include poverty and slow growth, which favor rebel recruitment and mark financially and bureaucratically weak states, rough terrain, and large populations.

The central puzzle about war, and also the main reason we study it, is that wars are costly but nonetheless wars recur. Scholars have attempted to resolve the puzzle with three types of argument. First, one can argue that people (and state leaders in particular) are sometimes or always irrational. They are subject to biases and pathologies that lead them to neglect the costs of war or to misunderstand how their actions will produce it. Second, one can argue that the leaders who order war enjoy its benefits but do not pay the costs, which are suffered by soldiers and citizens. Third, one can argue that even rational leaders who consider the risks and costs of war may end up fighting nonetheless.This article focuses on arguments of the third sort, which I will call rationalist explanations. 1 Rationalist explanations abound in the literature on international conflict, assuming a great variety of specific forms. Moreover, for at least two reasons many scholars have given rationalist explanations a certain pride of place. First, historians and political scientists who have studied the origins of particular wars often have concluded that war can be a rational alternative for leaders who are acting in their states' interest-they find that the expected benefits of war sometimes outweigh the expected costs, however unfortunate

nternational crises are modeled as a political "war of attrition" in which state leaders choose at each moment whether to attack, back down, or escalate. A leader who backs down suffers audience costs that increase as the public confrontation proceeds. Equilibrium analysis shows how audience costs enable leaders to learn an adversary's true preferences concerning settlement versus war and thus whether and when attack is rational. The model also generates strong comparative statics results, mainly on the question of which side is most likely to back down. Publicly observable measures of relative military capabilities and relative interests prove to have no direct effect once a crisis begins. Instead, relative audience costs matter: the side with a stronger domestic audience (e.g., a democracy) is always less likely to back down than the side less able to generate audience costs (a nondemocracy). More broadly, the analysis suggests that democracies should be able to signal their intentions to other states more credibly and clearly than authoritarian states can, perhaps ameliorating the security dilemma between democratic states.

Five factors are shown to be strongly related to civil war duration. Civil wars emerging from coups or revolutions tend to be short. Civil wars in Eastern Europe and the former Soviet Union have also tended to be relatively brief, as have anti-colonial wars. By contrast, ‘sons of the soil’ wars that typically involve land conflict between a peripheral ethnic minority and state-supported migrants of a dominant ethnic group are on average quite long-lived. So are conflicts in which a rebel group derives major funding from contraband such as opium, diamonds, or coca. The article seeks to explain these regularities, developing a game model focused on the puzzle of what prevents negotiated settlements to long-running, destructive civil wars for which conflicting military expectations are an implausible explanation. In the model, regional autonomy deals may be unreachable when fluctuations in state strength undermine the government’s ability to commit. The commitment problem binds harder when the center has an enduring political or economic interest in expansion into the periphery, as in ‘sons of the soil’ wars, and when either government or rebels are able to earn some income during a conflict despite the costs of fighting, as in the case of contraband funding.

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.