The notion that “states make war, and war makes states” has been a prominent concept in the study of international relations. In this widely cited phrase, Charles Tilly’s (1992) Coercion, capital, and European states, AD 990–1992 famously articulated the implicit relationship between the empirical construction of the European nation-state and the historical processes that gave rise to it. In light of the necessity to either resist or to bear the risk of being swallowed by other states, Tilly identified the effective preparation and conduct of violent conflict as the primary driver of the evolution of other social systems, including political decision-making, social welfare, and the emergence of national sentiments.

Yet, the empirical observation that states make war does not necessarily mean that warfare is accepted as a “normal” or even inevitable feature of statecraft. This is where Hendrik Simon’s “‘A Century of Anarchy?’ War, Normativity, and the Birth of Modern International Order,” comes in. It pursues the question of whether European states believed they had a “natural” right to wage war, beyond the context of territorial self-defense, and considers the extent to which such ideas were widely accepted or contested.

In his book, Simon uses the arguably “hard case” of the nineteenth century to offer a meticulously documented and sophistically argued re-examination of the ways in which post-Napoleonic Europe struggled with the notion of ius ad bellum. By examining a vast array of heterogeneous sources representing governmental, legal, historical, and philosophical perspectives, Simon effectively demonstrates the significant divergence of opinions regarding the circumstances under which states had the right to engage in warfare. This challenges the assumption that the nineteenth century represented the pinnacle of Realpolitik, characterized by the belief in the necessity of reckless state behavior in the absence of a coherent international legal framework. Furthermore, Simon asserts that the concept of an unrestricted ius ad bellum was devised by German legal scholars who sought to justify their country’s militaristic policies following the Franco-Prussian War. The deconstruction of the myth of an “anarchic” nineteenth-century international order enables Simon to restore, on the one hand, the empirical plurality of justifications of warfare and, on the other, to demonstrate how short-term political interests influenced intellectual and academic discourses.

In order to achieve this, Simon presents the empirical plurality of justificatory discourses after the conclusion of the Napoleonic Wars. He argues that these wars, which had a significant impact on many other areas of European society, fundamentally altered the perception of war itself. This is because they marked, at least in the perception of contemporary diplomats, the advent of “people’s wars” and their escalating consequences. The Congress of Vienna thus signals the emergence of an embryonic yet uncodified norm prohibiting offensive war, while simultaneously justifying military interventions against what could be termed “rogue states” in the present era. Among contemporary philosophers and legal scholars, Simon identifies a multiplicity of positions, ranging from those who align with Kantianism and argue for the necessity of internationally agreed, legal criteria for the justification of war, to those who espouse Clausewitzean views and contend that wars are driven by a political purpose defined by their respective communities. While wars did not cease after the Congress, the majority of legal scholars did however adhere to the notion that war could only be justified under narrow legal or moral conditions. However, there was considerable debate among scholars as to which specific conditions these were, with arguments centering on the merits of national self-determination, the expansion of “liberal” empires, or the defense of “universal” legal principles.

In the second part of the study, Simon reconstructs the debates that led to the ascendancy of Clausewitzean legal scholars in the context of the German Empire after 1870. Adopting either a positivist or a Darwinist perspective on international law, they effectively established a legal doctrine that justified the nationalist militarisation of the Empire and its growing disregard for diplomacy in favor of military preparedness, thereby contributing to the global arms race that reached its zenith in World War I. While this doctrine of a legally and morally unrestricted right to war was dominant (yet still contested) in the prewar German Empire, it remained relatively unpopular and isolated among other European legal schools until 1914. This observation serves to illustrate Simon’s main claim regarding the significance of the presence of multiple, albeit discernible, norms that governed the justification of European warfare in the nineteenth century.

The principal methodological tool deployed by Simon is historical discourse analysis. While this approach may appear straightforward for a scholar seeking to deconstruct narratives about the evolution of international law, one must commend the courage required to bring together discourses produced by intellectuals and officials in contexts spanning over 150 years and multiple national communities. Whereas this choice precludes the use of narrowly defined corpora and indicators in the research design, it does permit an examination of the interconnections between scholarly discourse, governmental politics, and broader intellectual evolutions. Thus, the identification of a German “Sonderweg” justifying the unrestricted use of force as a necessary means of foreign policy would not have been possible without simultaneously taking into account the perceptions of the international environment held by Prussian diplomats, pathways for collaboration selectively opened to bellicist legal scholars, and domestic ideational and institutional evolutions, including the increasing militarisation of pre-1914 German society.

In this regard, Simon illustrates the heuristic potential of adopting a hermeneutic approach to discourse analysis that embraces rather than reduces complexity. His analysis therefore reinforces the case for Historical International Relations, demonstrating persuasively how numerous well-established theoretical narratives in IR are, in fact, based on tenuous historical evidence. Concurrently, one might inquire as to which audience will be most amenable to Simon’s arguments. Unlike IR scholars, historians are already well aware that the nineteenth century was not characterized by an absence of social order and normative structures. Scholars of legal history will undoubtedly gain considerable insights from Simon’s emphasis on the impact of short-term political interests, professional changes, and institutional settings on the formulation of legal doctrines for war. For IR scholars, the occasional lengthy reconstruction of discussions among legal experts may sometimes appear a bit overwhelming.

Moreover, for an IR audience, there is a piece that is missing from the puzzle of why the vision of an “anarchic” nineteenth century has become so dominant in the discipline: Simon’s book, except for a short discussion in chapter 10, lacks a proper analysis of the ways in which the arguments of German imperial and post-imperial scholars have become integrated into the discipline’s intellectual evolution after 1945. It is evident that prominent theorists such as Carr and Morgenthau espoused comparable perspectives on the proclivity of the state for war, and that Carl Schmitt still today serves as a “bridge” connecting German bellicist philosophy and both mainstream and critical IR scholars. However, what about the foundational experience of the 1930s, including the perceived inadequacy of the Society of Nations compared to the role of military superiority in stopping and preventing foreign aggressors? In other words, can the perceived lessons of the Second World War provide a more plausible explanation of the intellectual evolution of post-1945 IR, including its belief in the anarchic nature of the nineteenth-century international order? This criticism gains even more weight considering that, according to Simon’s own analysis, already in their time of writing German bellicist scholars achieved little resonance outside the borders of the Empire.

Even if we accept the premise that their discourses have, at the very least, served to legitimize the myth about the “anarchic” nineteenth century that has become central to early IR theories: In light of Mary Douglas’ insights on the role of institutions in shaping collective memory, it is pertinent to inquire why this multitude of normative discourses on the justification of war has remained “forgotten” even after the end of the Cold War. Why, as Simon correctly notes, are contemporary conceptualizations of the history of international orders still “characterized by black-and-white thinking” (p. 366)? Simon posits that the two dominant narratives in IR—the liberal-ideational and the neo-realist—both rely on the premise that the nineteenth century was characterized by an “anarchic” and warlike order. However, he fails to acknowledge the extent to which the two classical IR narratives have become contested since the 1990s. Nevertheless, even post-positivist scholars appear to find it difficult to accept that the contemporary international order, challenged as it is, may have more in common with its nineteenth-century predecessor than is commonly acknowledged. It could be argued that one of the characteristics of the contemporary order is precisely the forgetting of its pre-1914 roots, thus facilitating its own stability and legitimacy by fostering the belief in a “rupture” with earlier, dark ages of European statehood.

Nevertheless, thanks to the richness of its empirical analysis and the originality of its main argument, Hendrik Simon’s study will undoubtedly become a reference point in debates on nineteenth-century international order, as well as the intellectual sources and blind spots of the IR discipline. While current trends in scholarship appear to favor either micro-sociological post-positivist observations or the positivist testing of variables using quantitative datasets, Simon’s work emphasizes the continued necessity for studies with an encompassing, ambitious research question and a qualitative methodology capable of identifying broad tendencies across geographic and temporal boundaries.