I consider a model in which two states choose how much to arm and whether to attack in successive periods. Arms are useful not only for deterrence or taking territory, but also because they influence the resolution of a set of disputed issues. States can cooperate on the issues by limiting military competition, but only as far as an endogenous “war constraint” allows. Factors determining the tightness of the war constraint imply hypotheses about the international determinants of military effort and thus the costs of anarchy. The strategic logic differs from standard security-dilemma arguments, in which the costs of anarchy are associated with conflict between status quo states that are uncertain about others' territorial revisionism. Here, inefficiency arises because arming to deter lowers a state's value for living with the status quo, which creates a security externality and a feedback loop. The model both synthesizes and revises a range of theoretical arguments about the determinants of interstate cooperation and conflict.

Social cooperation is critical to a wide variety of political and economic outcomes. For this reason, international donors have embraced interventions designed to strengthen the ability of communities to solve collective-action problems, especially in post-conflict settings. We exploit the random assignment of a development program in Liberia to assess the effects of such interventions. Using a matching funds experiment we find evidence that these interventions can alter cooperation capacity. However, we observe effects only in communities in which, by design, both men and women faced the collective action challenge. Focusing on mechanisms, we find evidence that program effects worked through improvements in mobilization capacity that may have enhanced communities’ ability to coordinate to solve mixed gender problems. These gains did not operate in areas where only women took part in the matching funds experiment, possibly because they could rely on traditional institutions unaffected by the external intervention. The combined evidence suggests that the impact of donor interventions designed to enhance cooperation can depend critically on the kinds of social dilemmas that communities face, and the flexibility they have in determining who should solve them.

When Things Fell Apart manages to be wonderfully concise but still compelling. The thing Robert Bates seeks to explain is the secular trend in sub-Saharan Africa toward civil war, although he often characterizes this in broader terms, as a trend toward “political conflict” or “political disorder.” He explains the trend as follows: Public revenues fell in the 1970s and 1980s as a result of commodity price declines, effects of the second oil shock, and bad economic policy choices that overtaxed farmers so that politicians could dispense patronage to smaller, politically more important urban constituencies. The decline in public revenues led elites to become more predatory, which caused an increase in political conflict by mobilizing opposition. Popular demands for political reform, along with increased international pressure for the same at the end of the Cold War, heightened elite insecurity and led to more predation. This had the effect of “provoking their citizens to take up arms” (p. 109). Further, state decline and national-level conflicts exacerbated simmering subnational conflicts, typically in the form of land disputes between locals and migrants from other tribes.

Partly hidden beneath the complexities of N* and an attack on the supposedly individualist presumptions of ethnic fractionalization measures, a simple and valuable question lies implicit in Cederman and Girardin's (2007) article (henceforth, CG). Are countries at greater risk of civil war when the state is controlled by an ethnic minority?

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 and religious antagonisms. We show that the current prevalence of internal war is mainly the result of a steady accumulation of protracted conflicts since the 1950s and 1960s rather than a sudden change associated with a new, post-Cold War international system. We also find that after controlling for per capita income, more ethnically or religiously diverse countries have been no more likely to experience significant civil violence 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. 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—which marks financially and bureaucratically weak states and also favors rebel recruitment—political instability, rough terrain, and large populations.We wish to thank the many people who provided comments on earlier versions of this paper in a series of seminar presentations. The authors also gratefully acknowledge the support of the National Science Foundation (Grants SES-9876477 and SES-9876530); support from the Center for Advanced Study in the Behavioral Sciences with funds from the William and Flora Hewlett Foundation; valuable research assistance from Ebru Erdem, Nikolay Marinov, Quinn Mecham, David Patel, and TQ Shang; sharing of data by Paul Collier.

We examine the theoretical implications of the observation that ethnic identities are socially constructed for explaining ethnic violence, distinguishing between two classes of mechanisms. If individuals are viewed as the agents who construct identities, then constructivist explanations for ethnic violence tend to merge with analyses that stress strategic action by both elites and mass publics. In contrast, if discursive formations are the agents that construct ethnic identities, then constructivist explanations tend to merge with accounts that stress internal logics of specific cultures. Using the books under review as a “sample,” we find considerable evidence linking strategic aspects of ethnic identity construction to violence and more limited evidence implicating discursive systems. The most common narrative in these texts has largescale ethnic violence provoked by elites, often motivated by intra-ethnic conflicts. Followers follow, despite the costs, out of increased fear of thugs and armies “let go” by elites (both the other side's and their “own”) and often in pursuit of local grievances that may have little ethnic component. Several other mechanisms are also discussed, including the role of discursive systems in conditioning publics for violence and the role of violent efforts to enforce “everyday primordialism” by policing supposedly primordial ethnic boundaries.

Neoliberals and their neorealist critics have debated the relative importance of two main obstacles to international cooperation—problems of cheating and enforcement and problems of relative gains. By contrast, I argue that problems of international cooperation have a common strategic structure in which a third, distinct obstacle plays a crucial role. Almost regardless of the issue area, states must first resolve the bargaining problem of agreeing on terms before they can implement and begin to enforce an agreement. Furthermore, the bargaining and enforcement problems interact. Using a game model, I show that if states must bargain to determine the deal to be enforced, the “shadow of the future” cuts two ways. A high expectation of continued interactions may make enforcing the agreement easier, but it can also give states an incentive to bargain harder, delaying agreement in hopes of getting a better deal. Empirical evidence from trade and arms control negotiations suggests that this mechanism may help to explain the costly standoffs that are often observed in international politics and are problematic for received neoliberal theories.

Though both journalists and the academic literature on ethnic conflict give the opposite impression, peaceful and even cooperative relations between ethnic groups are far more common than is large-scale violence. We seek to explain this norm of interethnic peace and how it occasionally breaks down, arguing that formal and informal institutions usually work to contain or “cauterize” disputes between individual members of different groups. Using a social matching game model, we show that local-level interethnic cooperation can be supported in essentially two ways. In spiral equilibria, disputes between individuals are correctly expected to spiral rapidly beyond the two parties, and fear of this induces cooperation “on the equilibrium path.” In in-group policing equilibria, individuals ignore transgressions by members of the other group, correctly expecting that the culprits will be identified and sanctioned by their own ethnic brethren. A range of examples suggests that both equilibria occur empirically and have properties expected from the theoretical analysis.

Realist and other scholars commonly hold that rationally led states can and sometimes do fight when no peaceful bargains exist that both would prefer to war. Against this view, I show that under very broad conditions there will exist negotiated settlements that genuinely rational states would mutually prefer to a risky and costly fight. Popular rationalist and realist explanations for war fail either to address or to explain adequately what would prevent leaders from locating a less costly bargain. Essentially just two mechanisms can resolve this puzzle on strictly rationalist terms. The first turns on the fact that states have both private information about capabilities and resolve and the incentive to misrepresent it. The second turns on the fact that in specific strategic contexts states may be unable credibly to commit to uphold a mutually preferable bargain. Historical examples suggest that both mechanisms are empirically plausible.

International 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.

Scholars in comparative politics and international relations routinely evaluate causal hypotheses by referring to counterfactual cases where a hypothesized causal factor is supposed to have been absent. The methodological status and the viability of this very common procedure are unclear and are worth examining. How does the strategy of counterfactual argument relate, if at all, to methods of hypothesis testing based on the comparison of actual cases, such as regression analysis or Mill's Method of Difference? Are counterfactual thought experiments a viable means of assessing hypotheses about national and international outcomes, or are they methodologically invalid in principle? The paper addresses the first question in some detail and begins discussion of the second. Examples from work on the causes of World War I, the nonoccurrence of World War III, social revolutions, the breakdown of democratic regimes in Latin America, and the origins of fascism and corporatism in Europe illustrate the use, problems and potential of counterfactual argument in small-N-oriented political science research.