The Rise and Fall of Euro-American Inter-State War: Introduction

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.

The Internationalists: How a Radical Plan to Outlaw War Remade the World

Oona A. Hathaway and Scott J. Shapiro

New York: Simon & Schuster, 2017. xxii + 430 pp.

If one asked a group of historians, political scientists, and lawyers what they would consider the most important single treaty or international agreement of the last two centuries, one could expect a familiar set of names to be mentioned: Vienna, Versailles, the Geneva Conventions, Bretton Woods, Yalta, San Francisco, the GATT, Rome, Helsinki. Few would name the 1928 General Treaty for the Renunciation of War as an Instrument of National Policy, also known as the Paris Peace Pact and the Kellogg-Briand Pact, as the most significant. Yet this is the claim put forward by Oona Hathaway and Scott Shapiro in The Internationalists. The book is an original and provocative work that is grippingly written and makes an ambitious set of arguments spanning several different fields including history, international relations, political science, and international law. Hathaway and Shapiro are distinguished legal scholars at Yale Law School, where Hathaway teaches and works mainly on international law (besides her legal scholarship she has also served as Special Counsel to the General Counsel for National Security Law at the Pentagon); Shapiro holds appointments at the Law School as well as in the Philosophy Department at Yale.

The Internationalists contains three layers of analysis. The first recovers the Kellogg-Briand Pact and underscores its singular importance to world history. Yet the Paris Peace Pact emerges from the book not so much as a significant episode in its own right—only a dozen or so pages are devoted to the way the treaty actually came to be—but rather as a pivotal point in the history of international law since the early seventeenth century. The essential argument of the book therefore resides at a deeper level, in what Hathaway and Shapiro call the turn from the Old World Order to the New World Order.

The Old World Order is the umbrella term they use to describe the ensemble of basic assumptions underlying the law of nations between the early seventeenth and early twentieth century. Its premise was that war was the basic legal procedure for righting wrongs. International law did not care about which party to a conflict possessed a rightful claim, and whose cause was therefore the most just. War was the main arbiter of inter-state disputes, with the spoils and the mantle of justice accruing to the victor. Four legal rules followed from this: first, territorial conquest was legal; second, gunboat diplomacy was normal and permitted; third, economic sanctions as an alternative to war did not exist, because imposing them violated the impartiality that was essential to remaining legally neutral; and fourth, once a state of war existed, soldiers could kill, maim and slaughter without being held individually accountable.

Hathaway and Shapiro anoint Hugo Grotius (1583-1645) as the archetypal thinker of this order. Although they trace the key features of his thinking, their picture of the Old World Order does not depend on Grotius’ ideas alone. Hathaway and Shapiro provide a lucid tour d’horizon of the early modern philosophy of the laws of war. They point out the importance of war manifestos as expressions of grievances, shedding light on an understudied topic among historians of international law. Another chapter illuminates how the existence of a legal state of war allowed individuals to get away with murder. The overall picture that emerges is that of a legal universe that is radically different from the one we inhabit today. For centuries war was not only tolerated, but had an important regulative function in the international order because there were no overarching principles of right and wrong—in short, no substantive universal understanding of justice—on which all countries agreed.

The Old World Order is a stylized depiction of a historical era, but this is the point of the analysis: to create an ideal type of how the laws of war functioned. One of the key tenets of the Grotian system, inspired by a long tradition of humanist and republican thinking about war, was to suspend judgment on the justice or injustice of war between states. It did not matter who was right or wrong to begin a war—the outcome of war would be the source of subsequent right. Land and goods thus conquered became the sovereign soil and property of their conquerors (in a particularly interesting passage, Hathaway and Shapiro explain how this solved the problem of determining just title to property in a world where trade and war-making went hand in hand). This non-discriminating philosophy of war avoided the chaos of an international legal order in which every country had to victims and aggressors by themselves. The major price of seeing war as natural was that aggressive conquest was the normal way of expanding power and influence. Hathaway and Shapiro sum up the essential issue with the Old World Order by positing that “in the absence of global courts, if war is legal, Might must be Right, even if it is wrong” (55).

The philosophy of what they label the New World Order emerged after World War I. Abhorred by the violence of this enormous global conflict, the American internationalists Salmon Levinson and James Shotwell worked, in different contexts, to build support for a movement that would declare war itself illegal. The so-called outlawry movement became a significant social movement in the United States. Though they differed in their proposals, the shared basis of Levinson and Shotwell’s thinking was that an international legal ban on war would allow countries to disarm and embrace non-violent ways of settling their differences. They thought that restricting the horrors of war through more “humanity in warfare” was a fool’s errand: it was war itself that should be banned. The goal of the outlawry movement was to overturn the entire legal edifice built on the principle that Might made Right.

After many years of hard lobbying and organizing, these internationalists managed to convince French statesman Aristide Briand to propose a Franco-American treaty to renounce war. Though American Secretary of State Frank Kellogg was taken aback by the suggestion and offended by the backchannel diplomacy involved, he eventually came around to the idea, but proposed to turn it into a multilateral treaty. Thus Levinson and Shotwell’s cause achieved an unlikely triumph when in August 1928 the world’s statesmen gathered in Paris to sign the treaty that would come to be identified with the names of Briand and Kellogg. Within two years, it had been signed and ratified by sixty-three countries—nearly the entire global community at the time. The treaty’s signatories promised to “condemn recourse to war for the solution of international controversies, and renounce it, as an instrument of national policy in their relations with one another” and to “agree that the settlement or solution of all disputes or conflicts of whatever nature or of whatever origin they may be, which may arise among them, shall never be sought except by pacific means.”[1] The entire document could be fitted on a postcard, and it went further than any other international agreement ever had in outlawing war.

The New World Order contained in Kellogg-Briand reversed every aspect of the Old World Order. Now that war was no longer the principal procedure to settle disputes, conquest became illegitimate, neutrality largely disappeared from international law, economic sanctions became possible, and the atrocities committed as part of war became criminally punishable. The New World Order did not emerge overnight. A crucial intermediate step was the Stimson Doctrine, announced in 1931, which declared that the United States government would no longer recognize any newly conquered territory as belonging to the conqueror. With a few exceptions, from this point onward conquest no longer conferred legal title to territory.

Even so, the Kellogg-Briand Pact did not prevent a final cataclysmic war of aggression from breaking out in the late 1930s. Only during and after World War II did the political conditions arise in which the ban could be institutionalized effectively and used to create new jurisprudence. The International Military Tribunal (IMT, 1945-46) at Nuremberg and the associated twelve trials of the American Nuremberg Military Tribunals (NMT, 1946-1949) established important principles of international criminal justice. One of the strongest arguments for Hathaway and Shapiro’s case is that without Kellogg-Briand, the Allies would not have been able to indict Nazi leaders for the crimes of aggression and conspiracy to engage in aggressive war. The chapters on the outlawing of aggression and the Nuremberg trials are some of the best in the book, outlining the varied contributions of jurists like Hersch Lauterpacht, Carl Schmitt, Hans Kelsen, Bohuslav Ečer, William Chanler, Hermann Jahrreiss, and Hartley Shawcross. The post-war order also rested on the creation of the United Nations in 1945, whose Charter was significantly shaped by the Kellogg-Briand Treaty and by the ideas of James Shotwell and other American planners working under Sumner Welles at the State Department during World War II.

The third part of The Internationalists presents a series of empirical claims about the prevalence of wars of conquest and the changing forms of conflict over the last two centuries. These are based largely on datasets provided by the Correlates of War project, the Polity IV project and the World Bank. Hathaway and Shapiro demonstrate that wars of conquest in which large amounts of territory were exchanged almost disappeared after the consolidation of the New World Order in the late 1940s. They also claim that the Kellogg-Briand Pact made the world safer for small states to attain independence and protection against conquest. In this respect they note that although the international system has over three times as many states today as it did in 1928, many of these are weak polities that often suffer from intra-state (i.e. civil) wars. Finally, Hathaway and Shapiro propose that inter-state war as the way to solve to disputes has given way to practices of “outcasting” against transgressors of international norms by depriving them benefits of membership in global circuits of economic, cultural and technological exchange. They thus welcome the increasing use of economic sanctions as the key enforcement procedure of the New World Order.

Hathaway and Shapiro’s account is rich and provocative. The larger argument is powerfully made and pays attention to legal principle as well as the careers and personalities of the protagonists. The principal weakness of The Internationalists is its quite narrow and limited understanding of war and peace. The book assumes that war is a stable object or state of affairs that is either to be condoned (in the Old World Order) or condemned (in the New World Order). Hathaway and Shapiro understand the issue of what legally counts as war as a procedural question, or else a legal-philosophical one. While both these perspectives are valid, it ignores that war and peace assume their meaning through a process that is also always political in nature. Hathaway and Shapiro’s account ends in an explicit defense of early twenty-first-century liberal internationalism. As I will argue, this political orientation expresses itself in the particular type of war that is the focus of their book, first as the main form of justice, then as the target of outlawry. This concept of war is Euro-American, symmetrical, aggressive and inter-state in its character, and it is thus a much more historically and geographically specific phenomenon than they assume.

Underlying this misapprehension of the particular for the universal is Hathaway and Shapiro’s neglect of mediating domains between law and the state, especially the economic. The story that The Internationalists constructs about neutrality, sanctions, and gunboat diplomacy is too abstract and formalistic in its approach. A stronger account would consider how changes in the world economy and its international organization form an important backdrop to the decline of wars of conquest. The development of international law as well as the intellectual critique of war in the eighteenth and nineteenth century was bound up not only with the rise of the modern ‘Westphalian’ state system central to IR theory. It also happened as part of the expansion of a European-dominated global capitalism. As a result, international law always had a dual function: as a system of symmetrical rules to govern inter-state relations in Europe on the one hand, and as a vector for the creation of hierarchy in the global economy on the other. Tensions and transformations in this arrangement continued far into the twentieth century, and they are important to understanding what Kellogg-Briand did and did not mean.

In what follows, I will examine the strengths and weaknesses of The Internationalists in the aforementioned three domains, treating first its historical claims about the development of outlawry and treaties against aggression; then its legal-philosophical characterization of neutrality, gunboat diplomacy, and sanctions; and finally its empirical claims about the relation between trade, statehood, and conquest. I will add a few remarks about the importance of the boundary between war and peace, and conclude by placing the book in the wider historiography about war, peace, and international law.

[1] “Kellogg-Briand Pact 1928,” The Avalon Project: Documents in Law, History and Diplomacy, available at:

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About Nicholas Mulder

Nicholas Mulder is a PhD candidate in the Department of History at Columbia. He works on twentieth-century modern European and international history, with a special interest in political economy, varieties of internationalism, and the history of war. He is currently finishing his dissertation "The Economic Weapon: Interwar Internationalism and the Rise of Sanctions,'' which examines the interwar origins of economic sanctions in Euro-American politics between 1914 and 1945, and charts how this instrument initially became established as part of the disciplinary toolkit of today's international order. He will be a Postdoctoral Associate in 2019-2020 and Assistant Professor of Modern European History at Cornell University starting in fall 2020.