Beatrice Heuser has written a tour-de-force intellectual history of war in the Western world. The driving claim of War: A Genealogy of Western Ideas and Practices is that to understand war, we need to grasp the evolution of the ideas surrounding war, which involves moving away from the standard binaries that can be found in various disciplines that take war as a topic of study. Instead, we should take as our starting point (though, Heuser is careful to note, not necessarily our endpoint) the descriptive and normative viewpoints of the people who have engaged in and thought about war throughout its history in the West. Heuser rejects disciplinary boundaries and insists that the appropriate way to deepen our understanding of war is through a multilayered, multivalenced historical analysis that accepts multiple manifestations of warfare as instances of war, especially when they are described as such in the primary and secondary sources, despite their not fitting into modern popular imaginaries surrounding war. She argues that war is best understood as occurring within a range of continuums, the ends of each of which may look very different but are in fact all related by their inclusion under the umbrella concept of premeditated, organized intergroup violence. Her simultaneous focus on the changing realities of warfare and the social ideologies surrounding particular wars enables her to draw out and illuminate the praxis of war as it has occurred in the West. This book will be invaluable for anyone engaged in the serious study of war as a sociopolitical activity, and something that is both deeply normatively laden and a more-or-less constant fact of life in the Western world.

Throughout the book, Heuser brings her wide-ranging and varied expertise to bear, making it clear to readers that they are in good hands. One acknowledged limitation—I hesitate to call it a fault, as the book comes in at a hefty 448 pages—is that it discusses the genealogy of ideas only of Western warfare. This involves some line drawing regarding which histories count as “Western,” which as Kwame Anthony Appiah has argued, is always problematic. But here Heuser is in the same boat as other thinkers: we must draw boundaries somewhere, even though there is no way to do so without invoking and accepting a series of assumptions (that arose primarily in the early-modern colonial era) about who and what counts as Western and who and what is left out in the cold. Heuser acknowledges Europe's “mongrel heritage,” but focuses primarily on Judeo-Christian-Islamic influences, thus giving intellectual primacy to ancient Israel, parts of the Middle East, and the Greco-Roman-Mediterranean world (p. 6). While it is refreshing to see a genealogy of war that does not take as paradigmatic the early-modern and modern periods in Western Europe, it is worth noting that the book does put forward an idea of “the West” as a set of interconnected cultures and civilizations that has an authoritative intellectual canon. This claim is essential to Heuser's overall project: she argues that there are ideological through lines, traceable to that canon, running through and influencing the changing practices and sociopolitical realities of war in the West. (One of her recurring points is that nothing in war is as “revolutionary” as it seems [see especially pp. 56–58].) In other contexts, this demarcation of the West might be a potential area for critique; however, given Heuser's project, and the care with which she draws those lines, it is a sensible way to constrain a toweringly ambitious venture.

A key feature of the work is Heuser's insistence that war includes a whole spectrum of activities, including massacres, raids, sieges, guerilla undertakings, and more, as well as the social, economic, and logistical preparations for such warfare, and the inevitable minutia of conducting those activities. Her overturning of the “great battle” stereotype of what constitutes war is crucial; she draws the reader's eye to the plethora of nonbattle war actions that are often forgotten or, more perniciously, swept under the rug in popular and even academic histories of Western warfare. This attention to detail is emblematic of Heuser's research, and both scholars new to her work and those familiar with her previous offerings will appreciate the characteristically wide-ranging yet intricate portrait she paints of an ever-shifting phenomenon. She notes the necessarily “fuzzy boundaries” between “war,” “armed conflict,” and “not-war,” and focuses on the ways in which the conceptual and normative ideas surrounding war from theorists, practitioners, and those who straddle that line have both responded to and shaped the practices of war in the West (p. 126). While Heuser sometimes discusses the evolution of war, one of her main arguments is that war changes nonlinearly. While there are ideological and practical family resemblances (to use Wittgenstein's term) between wars, which we can make sense of by understanding them as falling within and contributing to an intellectual genealogy, it is not the case that war in the West has developed in only one direction along any given continuum (simple—complex, small—large, limited—total, symmetric—asymmetric, amateur—professional, etc.). As Heuser points out, practices of war shift in response to a multiplicity of structural and individual factors—including economic, social, political, cultural, intellectual, and ethical ones—and in turn war also shifts those factors. The result is that while changes in practices, conceptualizations, and evaluations of war are recognizably patterned, they are decidedly nonlinear and cannot be explained sufficiently by any single theoretical approach. A major element undergirding Heuser's entire discussion is the influence of religion on war, both directly, as providing justifications for war, and indirectly, as helping to set the cultural contexts in which wars occur. Still, she is careful to neither underplay nor overstate the role of religion; the result is a book sensitive to the wide array of factors at play in groups’ decisions regarding (a) going to war and (b) the modes and methodologies of fighting, and their normative evaluations of the same.

I must say that I remain unconvinced by Heuser's working definition of war as “premeditated, organized violence practised by one group against another” (p. 15). This allows genocide, ethnic cleansing, and other so-called mass atrocity crimes to fall under the rubric of war. While Heuser regards this as a feature of her account—she provides arguments throughout the book in support of this expanded meaning of “war”—I worry that it is a bug. Thinking predominantly from an ethics of war framework (my training is in Western just war theory and traditions), I regard war as a potentially morally justified activity, assuming that certain stringent moral, political, and pragmatic conditions are met. Of course, war in actual practice almost never meets these conditions; that is part of the tragedy of war. But just war theorists still hold that it is at least possible for war to be morally justified, when it is fought at the right time, in the right way, against the right enemy, and for the right purpose(s).

By contrast, genocide, ethnic cleansing, and other crimes against humanity can never be morally justified, regardless of circumstances. As Thomas Nagel has argued, war is conceptually subject to at least some moral restrictions that are absolute. When groups go beyond those restrictions, they may say they are committing acts of war—Nazi Germany claimed to be warring against the Jews—but they are mistaken because their actions are not even potentially morally justified. It is not that the Nazis, in planning and carrying out the Holocaust, fought a bad or wrong war. Rather, they did not fight a war against the Jews at all; they committed a genocide. This ethically meaningful distinction is lost if we accept Heuser's very broad definition of war.

This is a variation of the demarcation issue that is a long-standing difficulty in Western just war theory. As Heuser notes, such demarcation questions arise in part because of the fuzzy boundaries that are part and parcel of the long genealogies of thought and practice about war. Because she is primarily concerned with delineating and tracing the movement of those boundaries over time, I understand why she takes a more expansive view of war than many contemporary just war theorists; and it is still an open question as to who is correct regarding this issue.

Ultimately, this book serves as both a comprehensive investigation into how cultural narratives surrounding war arose and changed over time in light of practices of war, and an in-depth study of war-related conceptual and normative topics. It will be extraordinarily helpful for readers looking to comprehend how people and groups in the West have thought, and continue to think, about war and how they arrived at those understandings. The deeply appropriate upshot of Heuser's monumental work is an encouragement to think further and to reflect on how we might change our current cultural narratives and realities surrounding war now that we fully grasp their histories.