This book makes an important contribution to the study of war duration and conflict resolution. It asks: Why are some civil wars so difficult to resolve while others end quickly?

A dominant explanation for war duration centers on the commitment problem. Specifically, intrastate wars will be difficult to end and lasting agreements elusive when any negotiated deal reached today to end the violence may not be in the interests of the actors to uphold in the future, and thus, fearing the consequences of defection, both sides will prefer to continue to fight (e.g., see James D. Fearon, “Rationalist Explanations for War,” International Organization 49 [no. 3, 1995]: 379–414; Barbara F. Walter, “The Critical Barrier to Civil War Settlement,” International Organization 51 [no. 3, 1997]: 335–64). Trust and Fear in Civil Wars adds nuance to this theory of war duration by showing that the commitment problem is not constant across belligerent groups but, rather, varies in important ways because mistrust itself varies. This provides an important insight: Combatants are not equally likely to assume that their enemy will slit their throat if they surrender their weapons (p. 3). Additionally, Shanna Kirschner shows that warring factions not only fear that their adversary will renege on any peace deal but also fear the consequences of this breach of the deal. They weigh both the probability and the costs of defection.

According to Kirschner, these calculations are informed by assessments of the adversary’s reputation, specifically its execution of atrocities, policies of discrimination, and history of conflict. The predicted costs of a broken settlement are also influenced by individuals’ identifiability: their ability to “pass” as a member of another group and thus their vulnerability to being targeted in the event of a breached peace bargain. She argues that wars will be prolonged and difficult to resolve when parties do not trust each other to keep the peace and actors fear deadly repercussions should the accords break down. In contrast, where actors have mitigated levels of mistrust and anticipate lower costs to war recurrence, conflicts should be easier to resolve and therefore briefer in duration.

The book develops and evaluates this argument over the course of seven chapters. After laying out the theory in the first two chapters, Kirschner turns to quantitative analysis in Chapter 3. Here, she assesses the impact of past conflict, atrocities, discrimination, and identifiability on war duration using cross-national data that spans conflicts from 1945 to 2008. As she herself notes, the statistical analyses provide only weak tests of her theory. The theory is about information, reputations, perceptions, mistrust, and emotions. It tells a story about calculating probabilities, estimating costs, and weighing options. These concepts are not obviously amenable to quantitative study. Anyone looking for a solution to this challenge likely will be disappointed. The results are suggestive, but certainly not confirmatory of the proposed logic.

Kirschner seeks to explain an empirical regularity: that ethnic wars tend to be prolonged. Accordingly, she divides the sample into ethnic and nonethnic wars. While a useful analytic exercise, the data cast doubt on the robustness of her results. Against the observable implications of her theory, atrocities are not significantly correlated with ethnic war duration, and discrimination proves unrelated to non-ethnic war prolongation. Additionally, as a relevant control, Kirschner includes in her analyses “combatant capabilities” (p. 45). However, instead of conventional proxies such as relative power or force size, she uses “high atrocities” and “high discrimination.” Given that her key explanatory variables are atrocities and discrimination, these measures prove problematic as they likely introduce multicollinearity.

Given that these analyses cannot rigorously test the theory’s critical intervening variable of fear, in Chapters 4–6, Kirschner turns to qualitative controlled comparisons of cases that vary in outcome. In Chapter 4, she examines the Janatha Vimukthi Peramuna (JVP) insurrection in Sri Lanka, a short war, and the Tamil rebellion, a protracted war. She carefully weighs evidence derived from secondary materials and acknowledges that her proposed pathway is not the only one that matters; indeed, both conflicts ended through military defeat, begging the question: Why were government forces able to crush the JVP in a matter of weeks whereas it took them decades to defeat the Tamils? In Chapters 5 and 6, the author tells the stories of the Turkey-Kurdish war, which remains ongoing, and the Turkish Cypriot and Greek Cypriot conflict, which is frozen. She constructs the narrative on the basis of interviews of 67 individuals conducted during the summer of 2012. Her case studies bring the theory’s logic to life and offer opportunities to observe whether the protagonists’ statements are consistent with her theory’s predictions. While each case demonstrates its idiosyncrasies, together they offer valuable and complementary depth to the breath of her statistical cases. She concludes the book by briefly touching upon implications for policy and future research.

By pushing for greater nuance to the mechanisms underpinning protracted war, this book offers a valuable opportunity to reflect on the broader research agenda it motivates. Kirschner takes fear, mistrust, and insecurity seriously. These variables represent lynchpins in our theories, but are rarely subjected to empirical testing. Whereas she analyzes cross-national and case-based evidence, future research could exploit individual-level survey data to evaluate if the micro mechanisms of the credible commitment theory hold.

Most of the book’s discussion about identifiability, discrimination, and atrocities focuses on the population writ large. This raises the question of who the relevant agents of the theory should be. Who prolongs war? Who decides whether to negotiate, whether to leave the bargaining table, whether to break a cease-fire, and whether to return to war? Is it the civilian population: those who are identifiable, discriminated against, and victimized with violations of human rights? Both the quantitative measures and the interviews focus on “ordinary” citizens (p. 97). I am not so sure that these are the people responsible for the prolongation of war. I would argue that the armed organizations should have featured more prominently in the book’s fabric and should feature in future research on this topic.

Although the book’s unit of analysis is the armed group, in the quantitative analysis, atrocities are measured at the level of the conflict. In the qualitative analysis, Kirchner presents the highly asymmetrical nature of belligerents’ violence. According to the theory, mistrust and fear should be similarly asymmetric and bargaining failure one-sided: Negotiations should be initiated by the government, but doomed by the fearful rebels. These asymmetric dynamics in fear and bargaining failure are not considered in her work and may prove worthy of future study.

Kirschner evaluates two prominent explanations: the number of veto players and third-party guarantees. She finds the latter insignificant, but does not explain this puzzling result. I would anticipate that robust third-party guarantees would matter a great deal in determining the fears and costs of one’s adversary reneging. The author’s divergent finding could be an artifact of the fact that she collapses the life cycle of conflict and peace. For her, longer conflicts occur because “combatants may resist even negotiating … or [they renew] fighting after a brief truce. … [Or] while wars themselves may be fairly short, the underlying conflicts can persist … perhaps even breaking out into open war again (p. 40). However, as Barbara Walter indicates, there are reasons to expect the causes of fighting in these different phases to diverge in important ways. Commitment problems, for example, should loom especially large during negotiations. Evaluating how Kirschner’s logic of prolonged conflict varies over the course of the conflict cycle could prove an interesting extension of her research.

The logic of Trust and Fear in Civil Wars is appealing. Scholars have long believed that fear drives bargaining failure, but have not known where fear comes from. One challenge with studying fear and mistrust in war, however, is the potential circularity of the logic. Mistrust and atrocities may be seen as both a cause and an effect of prolonged war. Similarly, atrocities may heighten fear, but fear may also heighten atrocities. Identifying the precise causality in this important relationship would prove a fruitful avenue of future investigation. Additionally, whereas Kirschner follows scholarship in international relations and focuses only on security, integrating greed and other motivations would render the theory more comprehensive. To do so, future research could examine not only the belligerents’ expected costs of broken peace but also their expected benefits of preserved peace, such as amnesty, institutionalized power, and legalized assets.

Against the conventional wisdom, Kirschner shows us that disarming is not always a highly dangerous gamble. She illustrates that fears for the future are sometimes surmountable and that adversaries can sometimes credibly commit to peace (p. 3). In so doing, she advances our understanding of the ways to end civil wars and provides hope that peace may become sustainable.