This post is an advance version of a review essay that will appear in Humanity volume 10. It will be posted in five parts: one each day this week. This is part 5.
The interwar period was a time of heightened confusion about the boundary between war and peace. The meaning of both terms became thoroughly destabilized by political events. In this context the legal effort to end war through outlawry had unexpected and counterproductive effects. For by removing war from the realm of acceptable legal practices, it in fact increased the space for political actions that constituted war in all but name. The legal character of the ban on aggressive war has placed a permanent premium on de facto wars compared to de jure wars; if open war is illegal, then situations that are conflictual in real terms but have no existence in law are preferable to the transparent war as duel of the Old World Order.
Hathaway and Shapiro’s characterization of Shotwell, Levinson, Kellogg, Welles, and Lauterpacht as “Internationalists” is in keeping with the recent focus among historians to take internationalism as an umbrella term for various projects of transnational solidarity, exchange, cooperation, and institution-building. This literature has shown how such internationalists had quite complex relationships to nationalisms and partial allegiances of various kinds even as they engaged in their transnational work. Most of these men and women sincerely abhorred war. And as The Internationalists convincingly shows, a talented subset of American legal internationalists dedicated their careers to banishing it.
Yet we should not lose sight of the fact that many internationalists in the interwar period and thereafter also worked within war-making states. Many advocates of the League hoped that they could avoid war not so much because force had become irrelevant, but because after World War I the liberal powers held a preponderant share of it. Liberal states committed to internationalism were armed to the teeth and remained willing to use serious force against their opponents. The divide between realists and liberals in international relations and U.S. foreign policy, into which Hathaway and Shapiro cast their argument about the importance of the Paris Peace Pact, is not about whether this force should be used—that is something which both approaches agree on—but about the principles governing its use.
It is laudable and important that the ascendance of liberal internationalism has banished wars of aggression. Hathaway and Shapiro are frank about the fact that this internationalism has not resulted in the disappearance of war. But perhaps they do not go quite far enough to acknowledge that there are now many intra-state conflicts where there used to be inter-state wars. A sober view of the twentieth century shows that it is not just small and weak states that are involved in warfare. Liberal countries committed to internationalism have also continued to wage wars. It is worth bearing in mind that the three countries that fought most in the twentieth century were Britain, which has been involved in at least thirty wars from the Boer War in 1899 to the Kosovo War in 1999, followed closely by France (twenty-five wars) and the United States (twenty-one wars). The two Anglo-Saxon powers that defended liberalism thus fought substantially more wars than Germany (which fought five wars). Germany nonetheless remains the paragon of a warfare state in modern history.
Two problems surrounding war are particularly acute in the present. One is the end of formal declarations of war. The United States government has not formally declared war on another nation for the last 76 years. Thus interventions that are belligerent in all but name—air strikes, special forces raids, temporary incursions and occupations, economic sanctions, and blockades—have become ways to preserve alleged security and defend perceived national interests that in the Old World Order would have been recognized as forms of war. Declarations of war have legal consequences, because they bring into effect international humanitarian law and thereby confer rights and duties on both parties involved in the conflict. The virtual disappearance of declared wars has produced a situation in which wars have been stripped of much of their juridical baggage. Unsurprisingly, powerful countries are the main beneficiaries of this legal ambiguity. In a de jure war weak opponents are able to invoke international law to make claims for protection; in a condition of de facto war, this recourse to international law is impossible.
The second issue is that the hegemony of the language of non-aggression has been accompanied by an enormous inflation of the concept of self-defense. As Hathaway and Shapiro recount in detail, in the 1920s James Shotwell opposed Salmon Levinson because he wanted to make explicit that under the Pact “defensive war” would be the sole legal form of conflict. Levinson won that discussion, but Shotwell need not have worried: since Kellogg-Briand, defensive wars are the only modality of inter-state war. Even the initiation of the most destructive war of all time was shaped by the new discourse of non-aggression. A false flag attack carried out by SS soldiers in Polish uniforms against a German radio station on August 31, 1939 was used by Hitler to justify his invasion of Poland one day later under the pretext of self-defense. Hathaway and Shapiro’s claim that Kellogg-Briand’s ban on aggressive war was a major change is undeniably true at the discursive level. That even the most blatantly aggressive ideology in modern history paid lip service to non-aggression is proof of its rhetorical power. But it also raises serious questions about whether this idea alone could inaugurate the end of war tout court. It is the permissive flipside of non-aggression, the concept of self-defense, that has marked the history of international conflict from 1928 until today. Article 51 of the UN Charter does not only allow states to fight in response to attacks against themselves, but also to take up arms in defense of their allies—so-called “collective self-defense.” In the post-1945 period, the increased number of independent states caught up in the ideological struggle of the Cold War provided an unending source of legitimation for Third World interventions by the United States, European states, and the Soviet Union. European military responses to the breakdown of their colonial empires also exposed the imperial aspect of the bargain struck in Paris in 1928. After all, the colonial independence struggles that erupted from Indonesia to Algeria in the 1940s and 1950s faced massive military responses that were either in conformity with or almost invisible to international law. Exactly because it prevented aggression, Kellogg-Briand gave colonial authorities more leeway to wage counterinsurgency campaigns against native populations in the name of law and order, without having to fear their escalation into inter-state conflict.
The progressive redefinition of warfare in terms of self-defense has reached its apogee in the War on Terror. For the last sixteen years, the United States has lead a global effort against an unspecified enemy with an unclear geographic scope. The great paradox of the War on Terror is that even though it is waged against non-state actors, it has degraded and circumscribed the statehood of an increasing number of African, Middle Eastern, and Asian nations. Hathaway and Shapiro do not mention the War on Terror in their book, focusing instead of the more visible recent conflicts in Eastern Europe and the Middle East. They argue that “unless we want more Syrias and Ukraines, we must keep this background prohibition [on war] in place” (370). This is true, but also insufficient, for the ban on aggressive war did not prevent these civil wars from breaking out and spiraling out of control. Indeed, the stigmatization of inter-state aggression has encouraged all parties in these conflicts to keep their contributions either covert or dressed up as aid to states fighting in self-defense.
One may also ask whether a purely procedural definition of aggression—aggression is whatever the UN Security Council says it is—is sufficient. All too often such a definition appears to make the determination of war a question of power politics—the very Might makes Right situation that Hathaway and Shapiro want to escape. Hathaway and Shapiro show how the proceduralism of Shotwell and Levinson was key to the success of their outlawry movement. Agreeing on a substantive definition of aggression would have been too difficult. Brevity was the soul of peace. Yet, while adhering to a proceduralist understanding of the history of inter-state war and its demise, the final chapters of The Internationalists rest on more substantive criteria of just and unjust belligerents. Hathaway and Shapiro’s survey of contemporary conflicts and challenges often slips into morally and politically loaded language. In a revealing remark, they regretfully note that “the rules of the New World Order that provide so much benefit protect all states from the use of force, including those we do not want to protect because they are too feeble, chaotic, authoritarian, or, for lack of a better word, evil” (369). Besides the striking need to reach for the theological term evil to describe those states they deign unworthy of legal sovereignty, one wonders what their criterion is for deciding which states deserve to exist and which do not. These ruminations on contemporary politics are an unfinished aspect of the analysis of our modern world with which The Internationalists concludes its sweeping narrative.
By casting in such black-and-white terms the long-term development of international law, and the history of moral and political thought about war and peace with which it is bound up, Hathaway and Shapiro have produced a compelling and readable narrative, but a dubious and oversimplified account of history. It is tempting to write the histories with this kind of Manichean plot. A succession of two mutually opposed epochs divided by a clean break—a true pivotal moment at which value signs are inverted and old dogmas are completely overturned—makes for a dramatic narrative. Carl Schmitt’s Nomos der Erde remains one of the most striking instances of this form. Marti Koskenniemi’s standard history of international law was considerably more balanced, though it still ended on a wistful note. More recently, Isabel Hull has made a very thorough case for Germany’s uniquely hostile attitude to international law in World War I (ironically, Hull ended up reproducing the narrative structure of Schmitt’s Nomos about a stable and civilized international consensus challenged by a rogue power, but with a belligerent Imperial Germany rather than a crusading United States in the role of Great Disruptor).
Altogether, framing The Internationalists as an intervention into the enduring standoff between realists and idealists—in which Kellogg-Briand is chalked up as a victory for the latter—is less fruitful than trying to understand what these two approaches have in common: the Euro-American idea of symmetrical inter-state war between equals. The increase in the size, frequency, and intensity of inter-state and inter-imperial warfare between the seventeenth and the mid-twentieth centuries led legal thinkers and intellectual critics of war, from the perpetual peace theorists of the Enlightenment to the internationalists of the interwar years, to take this specific form of conflict as their chief object of regulation and target of criticism. The Internationalists is at its best a philosophical account of how this phenomenon was targeted, confronted, and decisively condemned. It shows the real and significant advance constituted by Kellogg-Briand and the radical opposition between different legal orders over time.
However, the Euro-American understanding of inter-state war covers only a portion of all the forms of violence and uses of force that cause death, cruelty, and suffering around the world. Western wars for hegemony peaked twice, first in the late eighteenth and early nineteenth century and then once more in the first half of the twentieth century. But they alternated with periods in which, as the historians Michael Geyer and Charles Bright have noted, “the multiplicity and disaggregation of conflicts matters most” and “violence [was] radically dispersed and decentered.” The challenge of war in the twenty-first century is much less likely to be a dark Schmittian revenge tragedy by revanchist rogue states than a continuing degeneration of conflict into an undeclared de facto “forever war” by the West and its allies against various imaginary enemies at the gates. This forever war sustains and is sustained by civil conflicts, and remains relatively unassailable because it is undeclared and justified by invoking self-defense. New legal, philosophical, and above all political tools will be needed to bring it into clearer focus, to contest the terms on which it is being waged, and to minimize its occurrence.
In fact, the disaggregation of modern wars into asymmetrical civil conflicts may force us to return to Grotius. The Dutch thinker was not only an international jurist, but also a historian and political thinker. His history of the Dutch Revolt Annales et Historiae de rebus Belgicis (1612-1613) puts forward a republican view of government and political order. Inspired by Tacitus’ writings on the tumultuous internal politics of the Roman Republic, Grotius emphasized the internal divisions among Dutch Protestants, the lure of collusion with foreign powers, the struggles between townspeople and their overlords, and the mutual suspicion between merchants and elites. He was not solely a theorist of inter-state war but one of civil war as well. In this sense, Grotius is a better guide to the modern world of dispersed violence than is suggested by Hathaway and Shapiro’s depiction of him, and a more thoroughly political analyst of the various forms of war.
The Internationalists is an ambitious book that raises big questions, recovers the important history of the outlawry movement, and deftly crosses disciplinary boundaries. But by viewing its limited cast of protagonists uncritically and portraying them as the long-lost forebears of contemporary liberal internationalism, it misses or distorts important historical trends and provides a very partial picture of the demise of inter-state war. While the book’s stylized transition from old to new world orders makes for a neat narrative, it constrains the accuracy of its arguments, especially where the League of Nations, neutrality, economic sanctions, and the development of territorial conquest are concerned. Hopefully future scholars can deepen and extend the discussion Hathaway and Shapiro have initiated with their work while avoiding both undue nostalgia about the past as well as excessive complacency about our own time, an era of wars that dare not speak their name.
 For a useful and concise genealogy of the war-peace binary from Grotius to the Cold War, see Anders Stephanson, “Fourteen Notes on the Very Concept of the Cold War,” in Rethinking Geopolitics, ed. Gearóid Ó Tuathail and Simon Dalby (London and New York: Routledge, 1998), 62–85.
 Hew Strachan has also acutely observed that since “international law has arrogated the decision to go to war, except in cases of national self-defense, to the United Nations. Even states involved in a de facto war do not declare war, so as to avoid breaches of international law. Paradoxically, therefore, international law has deregulated war. The notion that waging war is no longer something that states do is particularly prevalent in America and Europe” because “enemies tend to be portrayed either as non-state actors, or, when they are not, as failed states (the description applied to Afghanistan) or rogue states (that deemed appropriate in the case of Iraq).” The Direction of War: Contemporary Strategy in Historical Perspective (Cambridge: Cambridge University Press, 2013), 42.
 See, for example, Daniel Gorman, The Emergence of International Society in the 1920s (Cambridge: Cambridge University Press, 2012); Glenda Sluga, Internationalism in the Age of Nationalism (Philadelphia: University of Pennsylvania Press, 2013); Patricia Clavin, Securing the World Economy: The Reinvention of the League of Nations, 1920-1946 (2014); and the diverse array of essays in Glenda Sluga and Patricia Clavin, eds., Internationalisms: A Twentieth-Century History (Cambridge: Cambridge University Press, 2016).
 Hew Strachan, “Essay and Reflection: On Total War and Modern War,” The International History Review XXII, no. 2 (June 2000): 342.
 Carl Schmitt, The Nomos of the Earth in the International Law of the Jus Publicum Europaeum (Telos Press, 2006).
 Marti Koskenniemi, The Gentle Civilizer of Nations: The Rise and Fall of International Law, 1870-1960 (Cambridge: Cambridge University Press, 2001).
 Isabel Hull, A Scrap of Paper: Breaking and Making International Law During the Great War (Ithaca: Cornell University Press, 2014).
 See Michael Geyer and Charles Bright, “Global Violence and Nationalizing Wars in Eurasia and America: The Geopolitics of War in the Mid-Nineteenth Century,” Comparative Studies in Society and History 38, no. 4 (October 1996): 629. The first instance of this condition was in the mid-nineteenth century, when civil wars, rebellions, and uprisings occurred everywhere: the revolutions of 1848, the Taiping Rebellion (the single deadliest conflict of the entire nineteenth century with an estimated 20 to 30 million deaths, more than the entire First World War), the Indian Revolt of 1857, the American Civil War, the Paris Commune. The second period has occurred toward the end of the Cold War. As Hathaway and Shapiro note, the number of intra-state wars has spiked since the 1990s, with civil wars in the former Yugoslavia, the Caucasus, Afghanistan, the horn of Africa, the Sahel region, and Central Africa (particularly the DR Congo and Rwanda, where a major regional war between 1998 and 2003 caused over 5 million deaths) preceding a series of extremely bloody civil wars in Libya, Syria, Yemen that continue today.