Introduction

The aspiration for world peace is among the oldest and most persistent themes in political thought. From ancient religious visions of harmony to modern international law, human societies have repeatedly imagined a future free of war. Yet the intensity and character of this aspiration have varied dramatically across historical periods. At certain moments, world peace appeared not merely desirable but imminent, a goal within the reach of rational statesmanship and institutional design. At other times, the very idea was dismissed as naive or dangerous utopianism, a distraction from the hard realities of power politics.

This article examines the historical oscillation between optimism and pessimism regarding world peace. It asks three interrelated questions: In which historical periods did thinkers and political actors most strongly believe that world peace was achievable? What factors, whether intellectual, institutional, or material, drove these waves of optimism? And what caused successive generations to retreat from the ideal, concluding that perpetual peace was unattainable or that its pursuit was itself a source of danger?

The analysis proceeds chronologically, beginning with the early modern peace projects and the Enlightenment, moving through the nineteenth century Concert of Europe, the interwar liberal internationalism, the post-1945 institutional order, the post-Cold War moment, and contemporary debates. Each section identifies the dominant theories of peace, the mechanisms through which peace was expected to arrive, and the events or structural changes that ultimately undermined confidence in those theories.

Early Modern Peace Projects and the Enlightenment Vision

The earliest systematic proposals for perpetual peace in the Western tradition emerged in the seventeenth century, though their intellectual roots extend to medieval Christian universalism and classical Stoic cosmopolitanism. The modern discourse on world peace, however, took shape in response to the devastating religious wars that convulsed Europe between the sixteenth and seventeenth centuries. The Thirty Years’ War (1618–1648), which killed an estimated eight million people, created the political conditions for both the Westphalian state system and the first serious proposals to transcend it.

Among the earliest notable peace proposals was William Penn’s Essay Towards the Present and Future Peace of Europe (1693), which called for the creation of a European parliament to settle disputes between states (Van Den Dungen, 2000). Penn, a Quaker pacifist, envisioned a supranational body with powers of mediation that would render war unnecessary. Shortly thereafter, John Bellers published Some Reasons for an European State (1710), proposing a similar federation of nations. These Quaker peace plans reflected a distinctive theological conviction that human beings, guided by the inner light of conscience, could construct institutions capable of overcoming the violence of the state system.

The most influential early modern peace project was the Abbé de Saint-Pierre’s Projet pour rendre la paix perpétuelle en Europe (1713), published during the Congress of Utrecht that ended the Wars of Spanish Succession. Saint-Pierre proposed a grand alliance of European sovereigns who would renounce war, submit disputes to mediation, and guarantee mutual security against both foreign aggression and domestic revolution (Saint-Pierre, 1713). The project was ambitious in scope and remarkably detailed in its institutional provisions. Saint-Pierre believed that the self-interest of rulers, properly understood, would lead them to embrace collective security, since war was far costlier than the maintenance of a permanent alliance.

Reactions to Saint-Pierre’s project were mixed and illuminating. Voltaire and other philosophes ridiculed it as impractical, while Montesquieu and Rousseau treated it with greater sympathy even as they questioned its feasibility. Rousseau, who prepared an abridgment of the project in 1761, praised its moral vision but argued that the very sovereigns who would need to establish the alliance had no rational incentive to do so, since the existing system served their interests. In his Jugement sur la paix perpétuelle (published posthumously in 1782), Rousseau concluded that perpetual peace could not be achieved without revolutions, and that the cure might be worse than the disease (Frey, 2012).

The culminating philosophical statement of the Enlightenment peace vision was Immanuel Kant’s Zum ewigen Frieden (Toward Perpetual Peace), published in 1795. Kant’s essay broke with the convention of earlier peace projects in several important respects. Rather than appealing to the enlightened self-interest of monarchs, Kant argued that perpetual peace required three structural preconditions: republican constitutions within states, a federation of free states in international relations, and a cosmopolitan right of universal hospitality (Kant, 1795/2006). Kant rejected the idea of a single world government, which he feared would degenerate into tyranny, and instead advocated a voluntary federation that would grow gradually as republics demonstrated the benefits of peaceful cooperation.

What distinguished Kant’s theory was its combination of moral idealism and historical realism. Kant believed that perpetual peace was not merely a utopian dream but a practical duty grounded in the moral law. At the same time, he argued that the unsocial sociability of human nature, including the tendency toward competition, vanity, and conflict, would paradoxically drive humanity toward peace through a process of painful historical learning. Wars would eventually teach nations that cooperation was preferable to destruction, and the spread of commerce would make peaceful exchange more profitable than conquest (Kleingeld, 2006).

The Enlightenment period thus represents the first major flowering of systematic optimism about world peace. Several factors converged to make this optimism possible: the exhaustion produced by centuries of religious and dynastic warfare, the rise of rationalist philosophy and its faith in human perfectibility, the growth of international commerce and early globalization, and the emergence of republican political thought. The peace projects of this era were, however, largely theoretical exercises with limited practical influence on statecraft. The French Revolutionary and Napoleonic Wars (1792–1815), which engulfed Europe in two decades of nearly continuous warfare, demonstrated the enormous gap between philosophical aspiration and political reality.

The Nineteenth Century: Commerce, Concert, and Cautious Optimism

The aftermath of the Napoleonic Wars produced a new institutional experiment in peace maintenance: the Concert of Europe. Established informally at the Congress of Vienna (1815), the Concert was a system of regular consultations among the great powers, designed to manage disputes and prevent the recurrence of general war. While it never aspired to perpetual peace in the Kantian sense, the Concert represented a practical acknowledgment that the balance of power required active diplomatic management rather than mere equilibrium.

The relative peace that prevailed in Europe between 1815 and 1914 (sometimes called the Pax Britannica) fostered a growing belief that war between civilized nations was becoming obsolete. This belief was grounded in two developments: the expansion of international commerce and the codification of international law. The first Geneva Convention of 1864 and the Hague Conventions of 1899 and 1907 established rules governing the conduct of war and the peaceful settlement of disputes, reflecting a conviction that the international system could be progressively regulated through legal norms (Pedersen, 2007).

The most influential articulation of commercial pacifism came from Norman Angell, whose book The Great Illusion (1910) argued that economic interdependence had rendered war between industrial nations futile and self-defeating. Angell contended that because modern wealth was founded on credit and commercial contract rather than territorial possession, military conquest could not enrich the conqueror without destroying the very economic system on which prosperity depended (Angell, 1910). The book sold over two million copies and was translated into twenty-five languages, reflecting the enormous appetite for reassurance that war had become irrational.

Angell’s thesis was widely misinterpreted as predicting that war was impossible. In fact, Angell explicitly stated that war remained possible and even likely; his argument was that it was economically futile, not that it could not occur (Ceadel, 2011). Nevertheless, the popular reception of The Great Illusion illustrates the degree to which late nineteenth and early twentieth century publics were willing to believe that modernity had rendered large-scale war obsolete. The outbreak of World War I in 1914 shattered this confidence catastrophically, demonstrating that economic interdependence, far from preventing war, could amplify its destructive consequences.

The nineteenth century’s cautious optimism about peace was thus grounded in material conditions, specifically the growth of trade, the development of international law, and the relative stability of the European balance of power, rather than in philosophical conviction about human perfectibility. When those material conditions proved insufficient to prevent war, the optimism collapsed with extraordinary speed, giving way to the disillusionment and trauma that would define the interwar period.

The Interwar Period: Idealism, Institutionalism, and Catastrophic Failure

World War I, with its unprecedented scale of destruction and its approximately twenty million deaths, produced a paradoxical reaction: simultaneous horror at the reality of modern war and renewed determination to create institutions that would prevent its recurrence. The interwar period (1919–1939) represents perhaps the most intense and consequential phase of optimism about world peace, precisely because the stakes of failure were so visibly enormous.

The institutional centerpiece of interwar peace efforts was the League of Nations, founded in 1920 as part of the Paris Peace Conference. The League was the first intergovernmental organization whose principal mission was to maintain world peace through collective security, disarmament, and the peaceful settlement of disputes (Pedersen, 2007). Its creation was driven primarily by U.S. President Woodrow Wilson, who articulated his vision for a new international order in his Fourteen Points address of January 1918. Wilson argued that the balance of power system had failed catastrophically and must be replaced by a system of collective security in which aggression against any member would be met by the united response of all (Wilson, 1918).

The optimism surrounding the League was considerable, particularly in its early years. Scholarship from the interwar period reveals a pattern of cautious but genuine hope among academics and public intellectuals. Harriman, writing in 1927, expressed optimism for the League’s future while acknowledging institutional weaknesses (McGlinchey, 2010). Potter similarly noted that while the League had proven less successful than hoped, the prospect of a future without any international organization was unthinkable. Among British scholars of the period, idealism and support for the League were similarly pervasive. The League of Nations Union in Britain mobilized hundreds of thousands of citizens around the vision of collective security and world citizenship, creating what scholars have described as an emotional terrain of hope and international friendship (Wright, 2024).

Alongside the League, the interwar period produced other ambitious peace initiatives. The Kellogg-Briand Pact of 1928, signed by sixty-three nations, formally renounced war as an instrument of national policy. The Pact emerged from a broad-based outlawry movement that sought to delegitimize war entirely rather than merely regulate its conduct (Hathaway & Shapiro, 2017). The signing ceremony in Paris was greeted with popular enthusiasm, and the Pact was at the time the most rapidly ratified treaty in history.

The theoretical foundations of interwar peace optimism rested on what E. H. Carr (1939) would later term utopianism or idealism: the belief that rational argumentation, institutional design, and the force of public opinion could overcome the anarchic tendencies of the international system. Liberal internationalist scholars of the period denounced nationalism as a destructive ideology and viewed state sovereignty as a hindrance to peaceful interstate relations and human welfare (Öztığ, 2021). The catastrophic consequences of World War I had become a catalyst for theorizing about the conditions underlying peace, tapping into the rising anti-war sentiments among European societies.

The collapse of interwar optimism was dramatic and thorough. The League’s failure to respond effectively to the Japanese invasion of Manchuria in 1931 and Italy’s invasion of Ethiopia in 1935 exposed the fatal weakness of collective security without enforcement mechanisms. The years 1933–1934 marked a turning point: idealism seeking international cooperation was in retreat, while realism and the drive toward military expansion were on the rise (Park, 2023). The Kellogg-Briand Pact, lacking any enforcement provisions, proved powerless to prevent the rearmament of Germany, the expansion of fascism, and the march toward World War II.

Carr’s The Twenty Years’ Crisis, 1919–1939, published in 1939 on the eve of World War II, provided the definitive critique of interwar idealism. Carr argued that the liberal internationalist project had confused the interests of the satisfied powers with universal moral principles, that collective security was a fiction masking the refusal of status quo powers to enforce their own order, and that any viable international system must be grounded in a realistic assessment of power relations rather than in utopian aspiration (Carr, 1939). Carr’s work became foundational to the realist school of international relations, which would dominate the discipline for decades.

Several factors contributed to the collapse of interwar peace optimism. First, the institutional design of the League was fundamentally flawed: it lacked an independent military force, the United States never joined, and its decision-making procedures gave every member a veto. Second, the Versailles settlement created enormous grievances, particularly in Germany, that the League was unable to address. Third, the global economic crisis of the 1930s destroyed the material foundations of international cooperation and fueled the rise of fascist and militarist regimes. Finally, the ideological diversity of the international system, encompassing liberal democracies, fascist states, and the Soviet Union, meant that there was no shared normative framework on which collective security could rest.

The Post-1945 Order: Nuclear Peace, Institutions, and Bounded Optimism

The end of World War II in 1945 did not produce the kind of unbounded optimism that had characterized the immediate aftermath of World War I. The Holocaust, the atomic bombings of Hiroshima and Nagasaki, and the emerging Cold War confrontation between the United States and the Soviet Union tempered expectations dramatically. Nevertheless, the post-1945 period saw the construction of the most elaborate institutional architecture for peace in human history, including the United Nations, the Bretton Woods economic institutions, the European Coal and Steel Community (later the European Union), and a web of multilateral treaties and organizations.

The United Nations Charter (1945) explicitly drew on the lessons of the League’s failure. The Security Council was given enforcement powers, including the authorization of military force, that the League had lacked. Yet the veto power of the five permanent members ensured that the UN could not act against the interests of any major power, effectively reproducing the great-power concert system within a formally universal organization. The optimism of the post-1945 settlement was therefore more modest and pragmatic than its interwar predecessor: the goal was not to abolish war but to manage great-power conflict and prevent nuclear catastrophe.

The concept of the Long Peace, a term coined to describe the absence of direct military conflict between the major powers since 1945, became central to post-war discussions of international security. Pinker (2011) argued that this period represented part of a broader, centuries-long decline in violence, driven by the rise of the modern state, the expansion of commerce, the spread of literacy and cosmopolitanism, and the development of institutions of international cooperation. For Pinker, the Long Peace was not accidental but reflected deep structural changes in human civilization that favored peaceful cooperation over violent conflict.

Critics challenged this optimistic reading on multiple grounds. Clauset (2018) conducted a statistical analysis of war data from 1815 to the present and found that the apparent decline in major wars could plausibly be attributed to chance variation rather than a genuine structural trend. He concluded that recent trends would need to continue for another century or more before any statistically significant decline could be confirmed. Others pointed to the enormous destructiveness of proxy wars, civil conflicts, and state-sponsored violence in the developing world during the Cold War period, arguing that the Long Peace was a Eurocentric concept that ignored the ongoing suffering of populations in Asia, Africa, and Latin America.

The post-1945 period thus produced a form of bounded optimism: confidence that major war between great powers could be deterred through nuclear weapons, managed through institutions, and gradually rendered less likely through economic interdependence and the spread of democratic governance, but without the expectation that war itself would be abolished or that a truly global peace was imminent.

The Post-Cold War Moment: The End of History and the Democratic Peace

The collapse of the Soviet Union between 1989 and 1991 produced the most intense burst of peace optimism since the interwar period. The end of the Cold War appeared to vindicate the liberal internationalist vision: the ideological confrontation that had structured global politics for four decades had been resolved in favor of liberal democracy, and the spread of democratic governance promised to create the conditions for lasting peace.

The intellectual figurehead of this moment was Francis Fukuyama, whose essay “The End of History?” appeared in The National Interest in the summer of 1989, months before the fall of the Berlin Wall. Fukuyama argued that the end of the Cold War represented not merely the conclusion of a particular geopolitical conflict but the endpoint of humanity’s ideological evolution, with liberal democracy emerging as the final form of human government (Fukuyama, 1989). Drawing on Hegelian philosophy as mediated through Alexandre Kojève, Fukuyama contended that there were no viable ideological alternatives to liberalism, and that the major sources of conflict in human history, namely the struggle between competing political and economic systems, had been definitively resolved.

Fukuyama explicitly connected his thesis to the Kantian peace tradition, answering Kant’s question of whether a universal history from a cosmopolitan point of view was possible in the affirmative (Glendinning, 2021). The expanded version of his argument, published as The End of History and the Last Man (1992), made the democratic peace theory a central pillar of his analysis.

The democratic peace theory, which holds that democracies rarely or never go to war with one another, provided the empirical and theoretical foundation for post-Cold War optimism. The modern scholarly formulation of the theory emerged in the early 1980s with Michael Doyle’s seminal two-part article connecting Kant’s philosophy to contemporary liberal internationalism (Doyle, 1983a, 1983b). Doyle argued that liberal states had established a separate peace among themselves while remaining aggressive toward non-liberal states, and that the expansion of the liberal zone of peace offered the best prospect for global peace.

Bruce Russett and Zeev Maoz subsequently provided extensive statistical support for the democratic peace proposition, demonstrating that the correlation between joint democracy and the absence of war remained significant even after controlling for numerous potential confounding variables (Maoz & Russett, 1993). Russett argued that democratic culture affects how leaders manage conflicts, and that the normative expectation of peaceful dispute resolution within democracies extends to their relations with other democracies. Russett and John Oneal further developed what they called the Kantian peace theory, arguing that democracy, economic interdependence, and membership in international organizations jointly reduce the risk of war (Russett & Oneal, 2001).

The post-Cold War moment also saw the application of democratic peace theory to policy. Russett argued that promoting democracy offered the possibility of strengthening existing peaceful relations and expanding their scope globally (Russett, 2013). This logic informed the foreign policies of Western governments, particularly the United States, and provided intellectual justification for democracy promotion and, in some cases, military intervention.

The optimism of this period was further reinforced by material developments. The rapid expansion of global trade and financial integration in the 1990s recalled the commercial peace arguments of Angell and the nineteenth-century liberal tradition. Thomas Friedman’s popular “Golden Arches Theory of Conflict Prevention,” which held that no two countries with McDonald’s franchises would go to war, captured the spirit of the era in popularized form, echoing Kant’s perpetual peace through the lens of late-twentieth-century globalization (Friedman, 1999).

The Retreat from Optimism: The Twenty-First Century Reassessment

The post-Cold War euphoria proved short-lived. A series of events in the early twenty-first century progressively undermined confidence in the liberal peace thesis and the broader project of democratic peace.

The September 11 attacks of 2001 marked what many commentators called “the end of the end of history.” Fareed Zakaria used precisely this phrase, while George Will declared that history had “returned from vacation” (Fukuyama, 2001). The subsequent wars in Afghanistan and Iraq demonstrated that liberal democracies were quite willing to wage war, that democracy promotion through military force produced catastrophic results, and that the post-Cold War order was far more fragile than its architects had imagined.

The theoretical foundations of the democratic peace also came under sustained scholarly criticism. Rosato (2003) argued that the causal logic of democratic peace theory was flawed, challenging both the normative and institutional mechanisms that were supposed to explain why democracies avoid war with each other. Experimental research tested the micro-foundations of the theory and found limited support: neither regime type nor liberal norms appeared to significantly influence individuals’ willingness to support the use of force (Doolaege, 2020). The statistical foundations were similarly contested: scholars debated whether the observed absence of war between democracies reflected a genuine causal relationship or was an artifact of measurement decisions, the relative novelty of widespread democracy, or confounding variables.

Geopolitical developments further eroded confidence in the democratic peace. The rise of China as a major economic and military power without significant democratic liberalization challenged the expectation that modernization would inevitably produce political liberalization. Russia’s annexation of Crimea in 2014 and its full-scale invasion of Ukraine in 2022 demonstrated that territorial conquest, which the post-1945 order was supposed to have rendered obsolete, remained a tool of great-power statecraft. The retreat of democracy in countries such as Turkey, Hungary, and the Philippines undermined the assumption of democratic consolidation and expansion that had underlain the optimism of the 1990s.

Fukuyama himself, writing on the twenty-fifth anniversary of his original essay, acknowledged that while liberal democracy still lacked a serious ideological competitor, he was less idealistic than he had been during the heady days of 1989. He noted the failures of the Orange Revolution and the Arab Spring, as well as democratic backsliding in multiple countries, conceding that the biggest challenge for democratically elected governments was not ideological competition but their own failure to deliver security, economic growth, and basic public services (Fukuyama, 2014).

The early twenty-first century thus witnessed a comprehensive reassessment of the liberal peace thesis. The factors driving this reassessment were multiple: the persistence of armed conflict in many regions of the world, the rise of authoritarian great powers that showed no signs of converging toward liberal democracy, the fragility of democratic institutions even within established democracies, the weaponization of economic interdependence as a tool of coercion rather than a guarantor of peace, and the emergence of new forms of conflict, including cyber warfare and information warfare, that blurred the boundaries between war and peace.

Discussion: Patterns, Causes, and the Cyclical Nature of Peace Optimism

The historical survey presented above reveals several recurring patterns in the rise and fall of world peace as a political ideal. Understanding these patterns is essential for evaluating both the prospects for peace and the limitations of the theories that have been constructed to explain and promote it.

The catalytic role of war. Every major wave of peace optimism has followed a period of devastating conflict. The peace projects of the early eighteenth century emerged from the Wars of Spanish Succession; Kant’s perpetual peace was written during the French Revolutionary Wars; the League of Nations and the Kellogg-Briand Pact followed World War I; the United Nations and the European integration project followed World War II; and the democratic peace thesis gained its greatest influence after the Cold War. The paradox is striking: the very catastrophes that demonstrated the fragility of peace also generated the political will and intellectual energy to imagine alternatives. As Carr (1939) noted, the science of international relations was born from the aspiration to prevent the recurrence of war, and each generation of peace theorists drew its urgency from the disasters of the preceding generation.

The role of material and institutional conditions. Optimism about peace has consistently been associated with specific material conditions: economic interdependence, institutional innovation, and the perceived rationality of cooperative behavior. Angell’s commercial pacifism, Kant’s emphasis on the pacific benefits of trade, and the post-Cold War confidence in globalization all rested on the assumption that economic integration creates incentives for peaceful cooperation that outweigh the potential gains from conflict. The repeated failure of this assumption, most dramatically in 1914, suggests that economic interdependence is a necessary but insufficient condition for peace, and that it can be overridden by political passions, ideological commitments, and security dilemmas.

The importance of regime type. The democratic peace theory, which represents the most sustained modern argument for the achievability of world peace, rests on the claim that the domestic political character of states is the primary determinant of their external behavior. This idea, traceable to Kant’s insistence on republican constitutions, has received substantial empirical support in the finding that democracies rarely fight each other (Russett, 1993; Doyle, 1983a). However, the theory has struggled to explain why democracies remain willing to wage war against non-democracies, why democratic transitions are often associated with increased conflict, and why the expansion of democracy has not produced the global peace that the theory predicted. The theory’s limitations suggest that regime type is one important factor among many, rather than a sufficient condition for peace.

The problem of enforcement. A recurring theme in the history of world peace projects is the gap between aspiration and enforcement. Saint-Pierre’s grand alliance, the League of Nations, and the Kellogg-Briand Pact all suffered from the same fundamental weakness: they lacked credible mechanisms to compel compliance. Carr’s critique of interwar idealism, which emphasized the absence of any international authority capable of enforcing collective decisions, remains applicable to subsequent institutional arrangements. Even the United Nations Security Council, designed with enforcement powers, has been constrained by the veto mechanism and the reluctance of great powers to subordinate their interests to collective decisions.

The tension between universalism and pluralism. Theories of world peace have consistently assumed that the expansion of a particular set of values, whether Enlightenment rationalism, liberalism, democracy, or market capitalism, would create the normative consensus necessary for lasting peace. This assumption has been challenged by the persistence of ideological and cultural diversity in the international system. The interwar period demonstrated that fascism and communism offered powerful alternatives to liberal internationalism; the post-Cold War period has shown that authoritarianism can persist and even thrive alongside globalization. The universalist assumptions of peace theory have been further criticized from postcolonial perspectives, which point out that the liberal peace has historically been associated with imperial domination and the exclusion of non-Western societies from the benefits of the international order (Hobson, 2012).

Conclusion

The history of world peace as a political ideal reveals a recurring pattern of aspiration, institutional innovation, partial success, and disillusioning failure. Each generation of peace theorists has identified real and important factors that contribute to peaceful international relations, whether republican governance, economic interdependence, international institutions, or normative change. Yet each generation has also tended to overestimate the sufficiency of these factors and to underestimate the resilience of the forces that drive conflict: nationalism, security competition, ideological rivalry, and the sheer contingency of historical events.

The cyclical character of peace optimism is not, however, evidence that the pursuit of peace is futile. The institutional achievements of successive waves of peace activism, from the Concert of Europe to the United Nations to the European Union, have demonstrably reduced the frequency and destructiveness of interstate war, even if they have not eliminated it (Hathaway & Shapiro, 2017; Pinker, 2011). The challenge for contemporary peace theory is to retain the ambition of the Kantian tradition while incorporating the realist insight that peace requires not merely good intentions and institutional design but the management of power, the accommodation of diversity, and the recognition that progress is neither linear nor inevitable.

Perhaps the most enduring lesson of this history is that the belief in world peace flourishes precisely when it is most needed, in the aftermath of catastrophe, and recedes precisely when it is most tested, in the face of resurgent conflict. The task for scholars and statesmen is to sustain the institutions and norms that promote peace through periods of disillusionment, so that the achievements of one generation are not squandered by the complacency or despair of the next. As Kant recognized more than two centuries ago, perpetual peace is not a prediction but a duty: a moral obligation to be pursued regardless of whether its full realization is assured (Kant, 1795/2006).

 

References

Angell, N. (1910). The great illusion: A study of the relation of military power in nations to their economic and social advantage. G. P. Putnam’s Sons.

Carr, E. H. (1939). The twenty years’ crisis, 1919–1939: An introduction to the study of international relations. Macmillan.

Ceadel, M. (2011). The founding text of international relations? Norman Angell’s seminal yet flawed The Great Illusion (1909–1938). Review of International Studies, 37(4), 1671–1693.

Clauset, A. (2018). Trends and fluctuations in the severity of interstate wars. Science Advances, 4(2), eaao3580.

Doolaege, L. (2020). The microfoundations of normative democratic peace theory: Experiments in the US, Russia and China. Journal of International Relations and Development, 23(4), 951–975.

Doyle, M. W. (1983a). Kant, liberal legacies, and foreign affairs. Philosophy & Public Affairs, 12(3), 205–235.

Doyle, M. W. (1983b). Kant, liberal legacies, and foreign affairs, Part 2. Philosophy & Public Affairs, 12(4), 323–353.

Doyle, M. W. (1986). Liberalism and world politics. American Political Science Review, 80(4), 1151–1169.

Frey, D. (2012). La guerre et la paix perpétuelle de l’abbé de Saint-Pierre à Rousseau. Revue des sciences religieuses, 86(4), 455–473.

Friedman, T. L. (1999). The Lexus and the olive tree: Understanding globalization. Farrar, Straus and Giroux.

Fukuyama, F. (1989). The end of history? The National Interest, 16, 3–18.

Fukuyama, F. (1992). The end of history and the last man. Free Press.

Fukuyama, F. (2014, June 6). At the ‘end of history’ still stands democracy. The Wall Street Journal.

Glendinning, S. (2021). Europe: A philosophical history, Part 2: Beyond modernity. Routledge.

Hathaway, O. A., & Shapiro, S. J. (2017). The internationalists: How a radical plan to outlaw war remade the world. Simon & Schuster.

Hobson, J. M. (2012). The Eurocentric conception of world politics: Western international theory, 1760–2010. Cambridge University Press.

Kant, I. (2006). Toward perpetual peace: A philosophical sketch. In P. Kleingeld (Ed. & Trans.), Toward perpetual peace and other writings on politics, peace, and history (pp. 67–109). Yale University Press. (Original work published 1795)

Kleingeld, P. (2006). Editor’s introduction: Kant on politics, peace, and history. In P. Kleingeld (Ed.), Toward perpetual peace and other writings on politics, peace, and history (pp. xv–xliv). Yale University Press.

Maoz, Z., & Russett, B. (1993). Normative and structural causes of democratic peace, 1946–1986. American Political Science Review, 87(3), 624–638.

McGlinchey, S. (2010). E. H. Carr and the failure of the League of Nations: A historical overview. E-International Relations. https://www.e-ir.info/2010/09/08/e-h-carr-and-the-failure-of-the-league-of-nations-a-historical-overview/

Öztığ, L. I. (2021). Liberal IR theorizing during the early twentieth century: 1900–1939. In K. E. Jørgensen (Ed.), The liberal international theory tradition in Europe (pp. 23–48). Palgrave Macmillan.

Park, J. (2023). Disarmament conferences and a crisis of diplomacy in the interwar period: The road to World War II. In International security: A history of the modern world (pp. 137–168). Springer.

Pedersen, S. (2007). Back to the League of Nations: Review essay. American Historical Review, 112(4), 1091–1117.

Pinker, S. (2011). The better angels of our nature: Why violence has declined. Viking.

Rosato, S. (2003). The flawed logic of democratic peace theory. American Political Science Review, 97(4), 585–602.

Russett, B. (1993). Grasping the democratic peace: Principles for a post-Cold War world. Princeton University Press.

Russett, B. (2013). Liberalism. In T. Dunne, M. Kurki, & S. Smith (Eds.), International relations theories: Discipline and diversity (3rd ed., pp. 94–113). Oxford University Press.

Russett, B., & Oneal, J. (2001). Triangulating peace: Democracy, interdependence, and international organizations. Norton.

Saint-Pierre, C.-I. C. de. (1713). Projet pour rendre la paix perpétuelle en Europe. A. Schouten.

Van Den Dungen, P. (2000). The Abbé de Saint-Pierre and the English ‘Irenists’ of the 18th century (Penn, Bellers, and Bentham). International Journal on World Peace, 17(2), 5–31.

Wilson, W. (1918, January 8). Fourteen Points [Address to joint session of Congress]. Washington, DC.

Wright, S. (2024). “Some change of feeling and purpose”: The League of Nations Union, emotions, and world citizenship in Britain. Journal of Social History, forthcoming.