What does order in international affairs mean? Political Theology of International Order shows how predominant modern ideas of ordering power politics are contingent on medieval ideas of a higher ordering power. William Bain suggests that his “aim in this enterprise is to prompt theorists of international order to rethink the history of their subject by dispelling deeply entrenched myths and misunderstandings” (p. 14). With this rather ambitious goal, Bain has achieved great success. The book offers a thorough and definitive rethinking of conventional narratives about the secular character of modern international order by showing how they fail to acknowledge their continued theological contingency and ultimate Eurocentricity. Beyond this contribution, however, the book's historiography of international order thinking has more implications than the author explicitly suggests, since the process of rethinking the idea of international order raises a series of broad and important questions about not only the theological sources of predominant international thought but also the meaning and normatively legitimate visions of international order in a global, culturally diverse twenty-first-century context.

The book is organized into three parts. Part 1 excavates two distinct (and, as the author argues, incommensurable) conceptions of order that preoccupied medieval Christian theological debates: First, it takes on the concept of an “immanent order,” conceived of as people and things having a divinely prefigured place and role in the world, like pieces in a game of chess. This idea was challenged in medieval theology by the second conception, that of an “imposed order.” Such an order was conceived of as a human-made arrangement without a prefigured set of places and roles, like dealing a deck of cards, or arranging books on a shelf not according to a prefigured scheme, but as one may see fit. However, as Bain explains, while this latter conception was imagined as being humanly arranged, in its medieval theological conception there was still a higher power acting or speaking through humankind in the world. As this history of ideas unfolds, we see that the concept of a prefigured order faded from prominence and the idea of an imposed order came to predominate the modern theory of international order.

Part 2 traces this history of how the idea of an imposed order came to predominate the modern understanding of international order in works by such thinkers as Luther, Grotius, and Hobbes. The historiographical point of the book is to show continuities between the medieval and modern conceptions of order. As Bain explains, these continuities show that “the modern states system reflects a medieval way of thinking: a modern Middle Ages” (p. 184). By examining such continuities, he also shows how the role of God, once conceived of as speaking in the world through humankind, has gradually been excised from modern conceptions of order, making possible the peculiar modern Western normative problem of finding justifications for international order “beneath an empty sky” (p. 224). As such, this book offers a historiography akin to Charles Taylor's A Secular Age but is of special interest and importance to theorists of international order, a topic that Taylor's work only indirectly touches on. Political Theory of International Order is not about developing or advancing a political theology of international order. It is about how excavating political theologies of order shows their legacies in modern theories of international order. This does not mean that such theories are religious or even theological; only that they are indebted to medieval theological debates.

Part 3 of the book traces the history of international order thought in academic international relations theory. Bain shows, for instance, how the modern idea of an international anarchy, be it in a system or society, is an idea dependent on prior nominalist notions of the world as being composed of independent units that create or impose order in the world—except that the theology of God speaking through those units was deliberately forgotten long ago. While insights such as these are themselves important for understanding international order thinking, their contribution does more than show the unacknowledged theological legacies of “secular” approaches to international order; they evoke broad and important questions about international order in the twenty-first century. What kind of international order makes sense, if predominant ways of thinking about order have these specific cultural sources? If acknowledging the theological origins of predominant conceptions of international order undermines their global applicability and secular neutrality, are more culturally inclusive and culturally pluralist postsecular concepts of international order possibly coherent, or not? If the modern idea of a secular international order is Eurocentric and contingent on particular theological legacies, then how are alternative non-Western conceptions of order legitimated or relegitimated by these findings? Are such alternatives incommensurable, or not, and how are they contributing to the making of international order and disorder in a global context increasingly influenced by rising non-Western powers? By stimulating these questions, if not explicitly raising them, the argument and conclusions of Political Theology of International Order help clarify not only the limits of international order thought but also larger and important terrain for further studies into international order.

Lastly, the depth of detail in which the historical rethinking of international order is conducted, combined with the breadth of intellectual history covered, suggests that this book will reward reading and rereading by scholars of international order for many years to come.