Rarely does a cover convey with such accuracy a book's central argument as in John Mueller's The Remnants of War. Shot by Ron Haviv, maybe the most iconic photographer of the Yugoslav wars of the 1990s, the cover picture shows a Serb soldier celebrating the fall of the town of Vukovar. The middle-aged soldier is drunk as he downs a bottle of liquor with the town's ruins in the background. In fact, he looks more like a homeless man in any European or American city than anything we would associate with the modern military profession—an observation that summarizes Mueller's four-tiered argument.

First, Mueller argues, the world is experiencing a secular decline of major interstate war. While this decline has a structural and institutional underpinning (namely, the dramatic rise of state capacity, domestically and internationally), it is driven primarily by “idea entrepreneurs” who have managed to produce a massive and deep change in popular values, comparable to the decline in popularity of dueling and slavery. Second, modern civil wars are mostly fought by predatory violence entrepreneurs and armies consisting of little more than packs of criminals and bullies seeking to exploit state weakness in the poor periphery of the developed world. Third, because these warlords are undisciplined cowards, they can be easily defeated by modern professional armies; however, military interventions are unlikely because of the domestic politics of advanced industrial democracies. Last, there may be hope for an internal, as opposed to an external, solution to this problem of “residual war.” As governments of poor countries become more effective, they may be able to crack down on criminal warlords more effectively than they have been until now.

This is a sweeping, multifaceted, and complex argument that speaks to multiple research programs in political science, generates several policy recommendations, and addresses central issues of our time. I found the parts on the decline of major war, in particular, to be absolutely fascinating, and the effort to conceptualize violent conflict on a continuum going from small crime to terrorism to be very stimulating. In short, this is a nice example of a rich and erudite book that speaks to a larger public without sacrificing scholarly thoroughness.

A book review of this size can do little justice to such a multifaceted argument, hence my focus on one dimension of the argument, the character of modern civil wars: This is the part most central to the overall argument and certainly the newest component of an intellectual project that Mueller has honed over a number of years and publications.

The argument about the essentially criminal aspect of civil wars echoes the well-known theories of “new wars” and dovetails with the equally known claim about “greed” as a causal factor behind civil war. The main difference between Mueller and the proponents of these arguments lies in interpretation. What is new for the proponents of the “new war” and “greed” theses is just residual for Mueller, the kind of violent conflict that becomes visible after major forms of war have disappeared: Contemporary civil wars are “essentially ancient forms of criminal war in which criminals and thugs … engage in warfare in much the same way they did in medieval and early modern Europe” (p. 86).

Mueller makes a bold case for his argument, culling anecdotes from several sources and introducing nuance when there is a need for it. For example, he recognizes that the distinction between disciplined and criminal warfare is ideal-typical and often fuzzy. He also distinguishes between three types of civil warfare: “mercenary” warfare fought by recently empowered and unpoliced thugs, rather than ordinary citizens; “brigand” warfare related to state failure; and disciplined civil warfare, which does not display the kind of pathology evidenced in the former two types. Typical examples include the wars of former Yugoslavia and Rwanda (mercenary warfare), Liberia and Colombia (brigand warfare), and Sri Lanka (disciplined warfare). As these examples make clear, this is a hard distinction to measure and sustain. The Rwandan case, in particular, is the toughest one to fit into this framework.

Ultimately, Mueller forgoes the systematic exploration of the processes that produce these different types of civil warfare in the first place. Had he not, he would have been forced to examine the analytical content of this distinction in more depth. At present, this distinction hinges on rather fuzzy evidence and a commitment to a single dimension of civil war, namely, the fighters' motivations—hence, the unabashedly military-centric character of his analysis of civil war. Political and social elites, as well as the masses, play a minor role in his account. Besides the obvious pitfalls of such neglect, this choice generates two flaws. First, although Mueller is right to target the uncritical uses of ethnicity in many descriptions of civil wars, his own account remains seriously undertheorized: Ethnicity (or any other cleavage, for that matter) is reduced to an ordering cleavage, a selection mechanism used by thugs for targeting their victims. It may well be that ethnicity is epiphenomenal to the whole story, but such an argument would require more solid theoretical and empirical foundations. This weakness leads to some inconsistencies in the narrative as mass preferences enter surreptitiously into the analysis, when “fanatics” suddenly appear among the various groups of criminals, or revenge is subsumed to criminal activity. Second, he analytically conflates evidence about the small size of perpetrator groups with evidence about criminal motivations. However, such conflation is unwarranted. The fact that civil wars entail the participation of small groups of individuals rather than masses is compatible with all sorts of motivations among both categories.

Looking at Haviv's entire portfolio, rather than just the picture of the drunk soldier in the cover, one is confronted with the multidimensionality of the wars in the former Yugoslavia. Consider some shots: A Serb man cries as Croatian forces capture his town; well-disciplined Yugoslav federal troops celebrate a victory; a Serb woman burns all her socialist books; Bosnian crowds demonstrate while holding Tito's picture. Whether these dimensions are essential or incidental to the war's causality remains an open question, to be investigated both theoretically and empirically. Mueller should be commended for having written an ambitious and stimulating book that poses these fundamental questions with clarity and boldness.