It is not a good time to publish a book about war that begins, as Christopher Blattman’s Why We Fight does, by belaboring just how improbable armed conflict is—even between enemies, even when they engage in brinkmanship—because of the many incentives to avoid it. That isn’t to say Blattman is wrong to argue that war is relatively rare and that most conflicts that have the potential to turn violent are resolved peacefully. War is indeed “in the error term,” as the political scientist Erik Gartzke memorably put it: the factors social scientists have identified for explaining war don’t actually predict it very well, because something random and intangible divides rivals that have reason to use force from those that actually do so. And most don’t.

Rather, it is a bad time to dwell on war’s rarity because, as Russia’s bloody invasion of Ukraine has underscored, it only takes one to end thousands of lives and upend millions more. Those who fear war don’t do so irrationally out of erroneous judgments about its probability. They do so because war is horrible and it is only natural to fear horrible things, even if they happen infrequently. It is of little comfort to Ukrainians to know that their plight is uncommon. 

In Blattman’s defense, his objective in framing peace as the rule is to explain the exception. Why We Fight seeks to answer the question of why rival powers occasionally fail to settle their differences peacefully and instead resort to war. Despite its title, however, the book offers no real theory of war. Rather, it identifies five forces, mostly culled from the literature on bargaining and social choice theory, that create a kind of taxonomy for failed bargaining between rivals: the inability to enforce or monitor compliance with an agreement, uncertainty about intentions or resolve, unchecked or unlimited interests, misperceptions or miscommunications, and motives for fighting that are intangible, such as nationalism. Blattman offers these forces, one per chapter in the first half of the book, without suggesting how they might go together or when their presence is sufficient to predict war. He simply claims that in a “fragile” society, “the five forces have eliminated most of the room for two enemies to find a compromise.” 

Why We Fight is more successful as an introduction to the bargaining model of war, which seeks to explain conflict as a complex bargaining interaction. A development economist and professor of conflict studies at the University of Chicago, Blattman deftly translates knotty ideas from game theory and social choice theory for a lay audience, weaving in colorful anecdotes from his own life and travels. Parts of the book are compelling, in particular his account of postconflict development work he did together with his partner. But by focusing on abstract forces, Blattman largely neglects the main protagonists in war—sovereign states, the international system, and the leaders who make life-and-death decisions. Ultimately, it is the incentives, norms, and culture of these actors that explain why we fight. 


Part of the problem with Blattman’s book stems from his imprecise definition of war. Unlike most political scientists, who define war according to strict criteria, including a minimum threshold for battle-related deaths, Blattman defines it as “any kind of prolonged, violent struggle between groups.” Such wars need not kill or injure people or even be politically motivated. They can cause mostly property damage or involve violence used entirely for private ends. Gang warfare within prisons fits his definition, but the Cold War doesn’t. 

In political science, definitions are not so much true or false, right or wrong, but more or less useful. They limit scope and add precision. They help make arguments transparent and falsifiable. But Blattman’s definition of war isn’t just too ambiguous to be useful; it trivializes war to such an extent that it actively muddies the waters. 

Blattman describes as wars all manner of things that cannot be seriously considered such. He cites, for instance, soccer hooliganism of the kind the author Bill Buford describes in Among the Thugs, his horrifying account of riotous football fans in the United Kingdom. But as violent and destructive as these fanatics were, they were not engaged in an actual war. Some hooligans did ultimately commit war crimes in the conflicts in the former Yugoslavia, but that is not what Blattman argues. Instead, he seems to claim that hooliganism itself is war.

For war to fall by the wayside, its perpetrators must come to see it as grotesque, immoral, and unnecessary.

A narrower definition holds that wars are violent armed contests within or between countries over who will govern. In a world of sovereign states, control of the national government is the ultimate prize in war. Political scientists tend to be very precise about how many fatalities such struggles must produce, over what time frame, in order to qualify as wars. According to one commonly accepted definition of civil war, for instance, one or more armed actors must kill at least 1,000 people over the course of a year while attempting to take or retain control of part or all of a country, and there must be substantial losses on more than one side. For an interstate war, two or more countries must clash violently, again causing at least 1,000 deaths in a single year. Political scientists and historians disagree on the specifics, but they largely agree that war is distinct from other kinds of political violence, as are its causes. Russia didn’t invade Ukraine for the same reason that gangs terrorize communities in Colombia. Nor is a viable policy response to gang violence, or an effective approach to managing it, going to help end the war between Russia and Ukraine.

Blattman’s overly inclusive definition of war leads him to conflate it with “state fragility,” a term that is more common in policy circles than in scholarly ones but in neither place means war. Fragile, less developed places, such as Colombia or Liberia, may be more prone to political violence than stable, wealthy ones. They are not, however, in a state of war already.

Blattman’s taxonomy also fails to explain why some fragile countries collapse into war and some do not (in part because it fails to distinguish between the condition of fragility and that of war). To have advanced a real theory of war, he would have had to examine a single fragile case and detail how each of the drivers in his taxonomy interacted there to prevent successful bargains and thereby lead to violence. He might have also shown how expensive, time-consuming development efforts failed to prevent conflict in a fragile place that has lapsed into war. Instead, he offers a jumble of factors that do not meld into a coherent story of how war begins or might be ended. 


In the second half of the book, after laying out his five forces that drive conflict and fragility, Blattman turns to the characteristics that make “stable and successful societies” better able to strike bargains for peace. Outside active war zones, the development economist is on firmer ground, since observational studies are more feasible in such settings, and so the experimental methods of economists are better able to determine which stabilization and development techniques work and which don’t. The secrets of successful societies are interdependence, checks and balances, the enforcement of rules, and interventions such as peacekeeping missions and sanctions. Each counteracts at least one of the forces that cause bargaining failures, generating resilience. Blattman likens them to preventive medicine. 

At times, however, even this part of his analysis is flawed and ahistorical. For example, in attempting to refute the theory, most closely associated with the sociologist Charles Tilly, that war between European powers led to the creation of the modern state, he cites the irrelevant examples of Botswana and South Korea. “Warfare doesn’t play an obvious role in their success,” he writes of these “growth miracles of the twentieth century.” Setting aside the fact that Tilly’s theory pertains to state building, not economic growth, it is hard to understand why Blattman would cite a country that is still technically at war with the North as an example of a state forged by peace. Not only were South Korea’s institutions formed and transformed by military interventions, occupations, and experiences of war, but two of its early governments were military dictatorships. 

Syrian rebels fighting in Bosra al-Sham, Syria, March 2015

Having offered no theory of war, the book would have been ambitious to suggest paths to peace or even ways to achieve the characteristics of the stable, resilient societies set out as models. Why We Fight wisely avoids doing so. In lieu of solutions, it offers ten “commandments”—principles by which individuals who want to help generate more bargains short of war should operate. They are the following: differentiate simple problems from “wicked” ones, that is, ones with complex causes that are difficult to disentangle; don’t worship grand plans or best practices; don’t forget that policymaking is political; “honor thy margins,” or work incrementally; practice structured trial and error by tinkering with many potential solutions; learn from failure; be patient; expect less; be accountable; and “find your margin,” or zero in on the small piece of the world where you can tinker to good effect. These commandments might help aid and development workers do a better job. None of them, however, will help Ukrainians resist Russian aggression or help the United States and its allies resolve the crisis. 

In the relatively more predictable fragile societies and postconflict settings where Blattman has done much of his work, moreover, his most useful advice is already well heeded. Nongovernmental organizations and governments are no longer using cookie-cutter development planning. The World Bank has fundamentally changed its approach to fragile states, trading strict economic principles for broader ones that take into account security and equity. Even the U.S. State Department’s Stabilization Assistance Review, which in 2018 assessed the lessons learned from previous U.S. interventions, concluded that small pilot programs are often more effective than grand schemes at first. And the Global Fragility Act, passed in the U.S. Congress with overwhelming bipartisan support in 2019, sets out an ambitious strategy for a more humble, cooperative, and local approach to U.S. diplomacy and foreign assistance. But most of this, too, is not really about war. It is about social and economic development. 


In order to understand war—much less prevent or end it—one must pay much more attention to the state itself. States are fundamentally different from the gangs and firms that Blattman presents as belligerents in his book. They have sovereign authority and so have very different incentives than other actors in the international system. These incentives—to secure the territory claimed by a distinct political community and defend interests that extend beyond that territory—explain why states go to war with one another and why rebel groups go to war with a state in order to seize it or create a new one via secession. They also help explain why states make alliances that eventually drag them into war and why citizens willingly take up arms to defend their country.

But the incentive structure created by the international system of sovereign states does not fully account for why humans fight. War is both an institution and a culture, and as such it is a product of human decisions. As the political scientist John Mueller has argued, the most obvious way to prevent war is to change the culture of violence among states—that is, change leaders’ minds about when it is appropriate to wage war against other countries, foreign populations, or even their own citizens. Dueling was once culturally acceptable but is now obsolete. War might one day be a similar anachronism, although Blattman’s framework—in which war is the natural result of a breakdown in bargaining—doesn’t allow for this possibility. For such an enduring cultural institution to fall by the wayside, however, its perpetrators must come to see it as grotesque, immoral, and unnecessary—not just rare and improbable.

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  • BRIDGET L. COGGINS is Associate Professor of Political Science at the University of California, Santa Barbara.
  • More By Bridget L. Coggins