One World, Rival Theories

The study of international relations is supposed to tell us how the world works. It's a tall order, and even the best theories fall short. But they can puncture illusions and strip away the simplistic brand names — such as "neocons" or "liberal hawks" — that dominate foreign-policy debates. Even in a radically changing world, the classic theories have a lot to say.


The U.S. government has endured several painful rounds of scrutiny as it tries to figure out what went wrong on Sept. 11, 2001. The intelligence community faces radical restructuring; the military has made a sharp pivot to face a new enemy; and a vast new federal agency has blossomed to coordinate homeland security. But did September 11 signal a failure of theory on par with the failures of intelligence and policy? Familiar theories about how the world works still dominate academic debate. Instead of radical change, academia has adjusted existing theories to meet new realities. Has this approach succeeded? Does international relations theory still have something to tell policymakers?

The U.S. government has endured several painful rounds of scrutiny as it tries to figure out what went wrong on Sept. 11, 2001. The intelligence community faces radical restructuring; the military has made a sharp pivot to face a new enemy; and a vast new federal agency has blossomed to coordinate homeland security. But did September 11 signal a failure of theory on par with the failures of intelligence and policy? Familiar theories about how the world works still dominate academic debate. Instead of radical change, academia has adjusted existing theories to meet new realities. Has this approach succeeded? Does international relations theory still have something to tell policymakers?

Six years ago, political scientist Stephen M. Walt published a much-cited survey of the field in these pages (“One World, Many Theories,” Spring 1998). He sketched out three dominant approaches: realism, liberalism, and an updated form of idealism called “constructivism.” Walt argued that these theories shape both public discourse and policy analysis. Realism focuses on the shifting distribution of power among states. Liberalism highlights the rising number of democracies and the turbulence of democratic transitions. Idealism illuminates the changing norms of sovereignty, human rights, and international justice, as well as the increased potency of religious ideas in politics.

The influence of these intellectual constructs extends far beyond university classrooms and tenure committees. Policymakers and public commentators invoke elements of all these theories when articulating solutions to global security dilemmas. President George W. Bush promises to fight terror by spreading liberal democracy to the Middle East and claims that skeptics “who call themselves ‘realists’…. have lost contact with a fundamental reality” that “America is always more secure when freedom is on the march.” Striking a more eclectic tone, National Security Advisor Condoleezza Rice, a former Stanford University political science professor, explains that the new Bush doctrine is an amalgam of pragmatic realism and Wilsonian liberal theory. During the recent presidential campaign, Sen. John Kerry sounded remarkably similar: “Our foreign policy has achieved greatness,” he said, “only when it has combined realism and idealism.” International relations theory also shapes and informs the thinking of the public intellectuals who translate and disseminate academic ideas.

During the summer of 2004, for example, two influential framers of neoconservative thought, columnist Charles Krauthammer and political scientist Francis Fukuyama, collided over the implications of these conceptual paradigms for U.S. policy in Iraq. Backing the Bush administration’s Middle East policy, Krauthammer argued for an assertive amalgam of liberalism and realism, which he called “democratic realism.” Fukuyama claimed that Krauthammer’s faith in the use of force and the feasibility of democratic change in Iraq blinds him to the war’s lack of legitimacy, a failing that “hurts both the realist part of our agenda, by diminishing our actual power, and the idealist portion of it, by undercutting our appeal as the embodiment of certain ideas and values.”

Indeed, when realism, liberalism, and idealism enter the policymaking arena and public debate, they can sometimes become intellectual window dressing for simplistic worldviews. Properly understood, however, their policy implications are subtle and multifaceted. Realism instills a pragmatic appreciation of the role of power but also warns that states will suffer if they overreach. Liberalism highlights the cooperative potential of mature democracies, especially when working together through effective institutions, but it also notes democracies’ tendency to crusade against tyrannies and the propensity of emerging democracies to collapse into violent ethnic turmoil. Idealism stresses that a consensus on values must underpin any stable political order, yet it also recognizes that forging such a consensus often requires an ideological struggle with the potential for conflict.

Each theory offers a filter for looking at a complicated picture. As such, they help explain the assumptions behind political rhetoric about foreign policy. Even more important, the theories act as a powerful check on each other. Deployed effectively, they reveal the weaknesses in arguments that can lead to misguided policies.


At realism’s core is the belief that international affairs is a struggle for power among self-interested states. Although some of realism’s leading lights, notably the late University of Chicago political scientist Hans J. Morgenthau, are deeply pessimistic about human nature, it is not a theory of despair. Clearsighted states can mitigate the causes of war by finding ways to reduce the danger they pose to each other. Nor is realism necessarily amoral; its advocates emphasize that a ruthless pragmatism about power can actually yield a more peaceful world, if not an ideal one.

In liberal democracies, realism is the theory that everyone loves to hate. Developed largely by European émigrés at the end of World War II, realism claimed to be an antidote to the naive belief that international institutions and law alone can preserve peace, a misconception that this new generation of scholars believed had paved the way to war. In recent decades, the realist approach has been most fully articulated by U.S. theorists, but it still has broad appeal outside the United States as well. The influential writer and editor Josef Joffe articulately comments on Germany’s strong realist traditions. (Mindful of the overwhelming importance of U.S. power to Europe’s development, Joffe once called the United States “Europe’s pacifier.”) China’s current foreign policy is grounded in realist ideas that date back millennia. As China modernizes its economy and enters international institutions such as the World Trade Organization, it behaves in a way that realists understand well: developing its military slowly but surely as its economic power grows, and avoiding a confrontation with superior U.S. forces.

Realism gets some things right about the post-9/11 world. The continued centrality of military strength and the persistence of conflict, even in this age of global economic interdependence, does not surprise realists. The theory’s most obvious success is its ability to explain the United States’ forceful military response to the September 11 terrorist attacks. When a state grows vastly more powerful than any opponent, realists expect that it will eventually use that power to expand its sphere of domination, whether for security, wealth, or other motives. The United States employed its military power in what some deemed an imperial fashion in large part because it could.

It is harder for the normally state-centric realists to explain why the world’s only superpower announced a war against al Qaeda, a nonstate terrorist organization. How can realist theory account for the importance of powerful and violent individuals in a world of states? Realists point out that the central battles in the “war on terror” have been fought against two states (Afghanistan and Iraq), and that states, not the United Nations or Human Rights Watch, have led the fight against terrorism.

Even if realists acknowledge the importance of nonstate actors as a challenge to their assumptions, the theory still has important things to say about the behavior and motivations of these groups. The realist scholar Robert A. Pape, for example, has argued that suicide terrorism can be a rational, realistic strategy for the leadership of national liberation movements seeking to expel democratic powers that occupy their homelands. Other scholars apply standard theories of conflict in anarchy to explain ethnic conflict in collapsed states. Insights from political realism — a profound and wide-ranging intellectual tradition rooted in the enduring philosophy of Thucydides, Niccolò Machiavelli, and Thomas Hobbes — are hardly rendered obsolete because some nonstate groups are now able to resort to violence.

Post-9/11 developments seem to undercut one of realism’s core concepts: the balance of power. Standard realist doctrine predicts that weaker states will ally to protect themselves from stronger ones and thereby form and reform a balance of power. So, when Germany unified in the late 19th century and became Europe’s leading military and industrial power, Russia and France (and later, Britain) soon aligned to counter its power. Yet no combination of states or other powers can challenge the United States militarily, and no balancing coalition is imminent. Realists are scrambling to find a way to fill this hole in the center of their theory. Some theorists speculate that the United States’ geographic distance and its relatively benign intentions have tempered the balancing instinct. Second-tier powers tend to worry more about their immediate neighbors and even see the United States as a helpful source of stability in regions such as East Asia. Other scholars insist that armed resistance by U.S. foes in Iraq, Afghanistan, and elsewhere, and foot-dragging by its formal allies actually constitute the beginnings of balancing against U.S. hegemony. The United States’ strained relations with Europe offer ambiguous evidence: French and German opposition to recent U.S. policies could be seen as classic balancing, but they do not resist U.S. dominance militarily. Instead, these states have tried to undermine U.S. moral legitimacy and constrain the superpower in a web of multilateral institutions and treaty regimes — not what standard realist theory predicts.

These conceptual difficulties notwithstanding, realism is alive, well, and creatively reassessing how its root principles relate to the post-9/11 world. Despite changing configurations of power, realists remain steadfast in stressing that policy must be based on positions of real strength, not on either empty bravado or hopeful illusions about a world without conflict. In the run-up to the recent Iraq war, several prominent realists signed a public letter criticizing what they perceived as an exercise in American hubris. And in the continuing aftermath of that war, many prominent thinkers called for a return to realism. A group of scholars and public intellectuals (myself included) even formed the Coalition for a Realistic Foreign Policy, which calls for a more modest and prudent approach. Its statement of principles argues that “the move toward empire must be halted immediately.” The coalition, though politically diverse, is largely inspired by realist theory. Its membership of seemingly odd bedfellows — including former Democratic Sen. Gary Hart and Scott McConnell, the executive editor of the American Conservative magazine — illustrates the power of international relations theory to cut through often ephemeral political labels and carry debate to the underlying assumptions.


The liberal school of international relations theory, whose most famous proponents were German philosopher Immanuel Kant and U.S. President Woodrow Wilson, contends that realism has a stunted vision that cannot account for progress in relations between nations. Liberals foresee a slow but inexorable journey away from the anarchic world the realists envision, as trade and finance forge ties between nations, and democratic norms spread. Because elected leaders are accountable to the people (who bear the burdens of war), liberals expect that democracies will not attack each other and will regard each other’s regimes as legitimate and nonthreatening. Many liberals also believe that the rule of law and transparency of democratic processes make it easier to sustain international cooperation, especially when these practices are enshrined in multilateral institutions.

Liberalism has such a powerful presence that the entire U.S. political spectrum, from neoconservatives to human rights advocates, assumes it as largely self-evident. Outside the United States, as well, the liberal view that only elected governments are legitimate and politically reliable has taken hold. So it is no surprise that liberal themes are constantly invoked as a response to today’s security dilemmas. But the last several years have also produced a fierce tug-of-war between disparate strains of liberal thought. Supporters and critics of the Bush administration, in particular, have emphasized very different elements of the liberal canon.

For its part, the Bush administration highlights democracy promotion while largely turning its back on the international institutions that most liberal theorists champion. The U.S. National Security Strategy of September 2002, famous for its support of preventive war, also dwells on the need to promote democracy as a means of fighting terrorism and promoting peace. The Millennium Challenge program allocates part of U.S. foreign aid according to how well countries improve their performance on several measures of democratization and the rule of law. The White House’s steadfast support for promoting democracy in the Middle East — even with turmoil in Iraq and rising anti-Americanism in the Arab world — demonstrates liberalism’s emotional and rhetorical power.

In many respects, liberalism’s claim to be a wise policy guide has plenty of hard data behind it. During the last two decades, the proposition that democratic institutions and values help states cooperate with each other is among the most intensively studied in all of international relations, and it has held up reasonably well. Indeed, the belief that democracies never fight wars against each other is the closest thing we have to an iron law in social science.

But the theory has some very important corollaries, which the Bush administration glosses over as it draws upon the democracy-promotion element of liberal thought. Columbia University political scientist Michael W. Doyle’s articles on democratic peace warned that, though democracies never fight each other, they are prone to launch messianic struggles against warlike authoritarian regimes to “make the world safe for democracy.” It was precisely American democracy’s tendency to oscillate between self-righteous crusading and jaded isolationism that prompted early Cold War realists’ call for a more calculated, prudent foreign policy.

Countries transitioning to democracy, with weak political institutions, are more likely than other states to get into international and civil wars. In the last 15 years, wars or large-scale civil violence followed experiments with mass electoral democracy in countries including Armenia, Burundi, Ethiopia, Indonesia, Russia, and the former Yugoslavia. In part, this violence is caused by ethnic groups’ competing demands for national self-determination, often a problem in new, multiethnic democracies. More fundamental, emerging democracies often have nascent political institutions that cannot channel popular demands in constructive directions or credibly enforce compromises among rival groups. In this setting, democratic accountability works imperfectly, and nationalist politicians can hijack public debate. The violence that is vexing the experiment with democracy in Iraq is just the latest chapter in a turbulent story that began with the French Revolution.

Contemporary liberal theory also points out that the rising democratic tide creates the presumption that all nations ought to enjoy the benefits of self-determination. Those left out may undertake violent campaigns to secure democratic rights. Some of these movements direct their struggles against democratic or semidemocratic states that they consider occupying powers — such as in Algeria in the 1950s, or Chechnya, Palestine, and the Tamil region of Sri Lanka today. Violence may also be directed at democratic supporters of oppressive regimes, much like the U.S. backing of the governments of Saudi Arabia and Egypt. Democratic regimes make attractive targets for terrorist violence by national liberation movements precisely because they are accountable to a cost-conscious electorate.

Nor is it clear to contemporary liberal scholars that nascent democracy and economic liberalism can always cohabitate. Free trade and the multifaceted globalization that advanced democracies promote often buffet transitional societies. World markets’ penetration of societies that run on patronage and protectionism can disrupt social relations and spur strife between potential winners and losers. In other cases, universal free trade can make separatism look attractive, as small regions such as Aceh in Indonesia can lay claim to lucrative natural resources. So far, the trade-fueled boom in China has created incentives for improved relations with the advanced democracies, but it has also set the stage for a possible showdown between the relatively wealthy coastal entrepreneurs and the still impoverished rural masses.

While aggressively advocating the virtues of democracy, the Bush administration has shown little patience for these complexities in liberal thought — or for liberalism’s emphasis on the importance of international institutions. Far from trying to assure other powers that the United States would adhere to a constitutional order, Bush “unsigned” the International Criminal Court statute, rejected the Kyoto environmental agreement, dictated take-it-or-leave-it arms control changes to Russia, and invaded Iraq despite opposition at the United Nations and among close allies.

Recent liberal theory offers a thoughtful challenge to the administration’s policy choices. Shortly before September 11, political scientist G. John Ikenberry studied attempts to establish international order by the victors of hegemonic struggles in 1815, 1919, 1945, and 1989. He argued that even the most powerful victor needed to gain the willing cooperation of the vanquished and other weak states by offering a mutually attractive bargain, codified in an international constitutional order. Democratic victors, he found, have the best chance of creating a working constitutional order, such as the Bretton Woods system after World War II, because their transparency and legalism make their promises credible.

Does the Bush administration’s resistance to institution building refute Ikenberry’s version of liberal theory? Some realists say it does, and that recent events demonstrate that international institutions cannot constrain a hegemonic power if its preferences change. But international institutions can nonetheless help coordinate outcomes that are in the long-term mutual interest of both the hegemon and the weaker states. Ikenberry did not contend that hegemonic democracies are immune from mistakes. States can act in defiance of the incentives established by their position in the international system, but they will suffer the consequences and probably learn to correct course. In response to Bush’s unilateralist stance, Ikenberry wrote that the incentives for the United States to take the lead in establishing a multilateral constitutional order remain powerful. Sooner or later, the pendulum will swing back.


Idealism, the belief that foreign policy is and should be guided by ethical and legal standards, also has a long pedigree. Before World War II forced the United States to acknowledge a less pristine reality, Secretary of State Henry Stimson denigrated espionage on the grounds that “gentlemen do not read each other’s mail.” During the Cold War, such naive idealism acquired a bad name in the Kissingerian corridors of power and among hardheaded academics. Recently, a new version of idealism — called constructivism by its scholarly adherents — returned to a prominent place in debates on international relations theory. Constructivism, which holds that social reality is created through debate about values, often echoes the themes that human rights and international justice activists sound. Recent events seem to vindicate the theory’s resurgence; a theory that emphasizes the role of ideologies, identities, persuasion, and transnational networks is highly relevant to understanding the post-9/11 world.

The most prominent voices in the development of constructivist theory have been American, but Europe’s role is significant. European philosophical currents helped establish constructivist theory, and the European Journal of International Relations is one of the principal outlets for constructivist work. Perhaps most important, Europe’s increasingly legalistic approach to international relations, reflected in the process of forming the European Union out of a collection of sovereign states, provides fertile soil for idealist and constructivist conceptions of international politics.

Whereas realists dwell on the balance of power and liberals on the power of international trade and democracy, constructivists believe that debates about ideas are the fundamental building blocks of international life. Individuals and groups become powerful if they can convince others to adopt their ideas. People’s understanding of their interests depends on the ideas they hold. Constructivists find absurd the idea of some identifiable and immutable “national interest,” which some realists cherish. Especially in liberal societies, there is overlap between constructivist and liberal approaches, but the two are distinct. Constructivists contend that their theory is deeper than realism and liberalism because it explains the origins of the forces that drive those competing theories.

For constructivists, international change results from the work of intellectual entrepreneurs who proselytize new ideas and “name and shame” actors whose behavior deviates from accepted standards. Consequently, constructivists often study the role of transnational activist networks — such as Human Rights Watch or the International Campaign to Ban Landmines — in promoting change. Such groups typically uncover and publicize information about violations of legal or moral standards at least rhetorically supported by powerful democracies, including “disappearances” during the Argentine military’s rule in the late 1970s, concentration camps in Bosnia, and the huge number of civilian deaths from land mines. This publicity is then used to press governments to adopt specific remedies, such as the establishment of a war crimes tribunal or the adoption of a landmine treaty.

These movements often make pragmatic arguments as well as idealistic ones, but their distinctive power comes from the ability to highlight deviations from deeply held norms of appropriate behavior.

Progressive causes receive the most attention from constructivist scholars, but the theory also helps explain the dynamics of illiberal transnational forces, such as Arab nationalism or Islamist extremism. Professor Michael N. Barnett’s 1998 book Dialogues in Arab Politics: Negotiations in Regional Order examines how the divergence between state borders and transnational Arab political identities requires vulnerable leaders to contend for legitimacy with radicals throughout the Arab world — a dynamic that often holds moderates hostage to opportunists who take extreme stances.

Constructivist thought can also yield broader insights about the ideas and values in the current international order. In his 2001 book, Revolutions in Sovereignty: How Ideas Shaped Modern International Relations, political scientist Daniel Philpott demonstrates how the religious ideas of the Protestant Reformation helped break down the medieval political order and provided a conceptual basis for the modern system of secular sovereign states.

After September 11, Philpott focused on the challenge to the secular international order posed by political Islam. “The attacks and the broader resurgence of public religion,” he says, ought to lead international relations scholars to “direct far more energy to understanding the impetuses behind movements across the globe that are reorienting purposes and policies.” He notes that both liberal human rights movements and radical Islamic movements have transnational structures and principled motivations that challenge the traditional supremacy of self-interested states in international politics. Because constructivists believe that ideas and values helped shape the modern state system, they expect intellectual constructs to be decisive in transforming it — for good or ill.

When it comes to offering advice, however, constructivism points in two seemingly incompatible directions. The insight that political orders arise from shared understanding highlights the need for dialogue across cultures about the appropriate rules of the game.

This prescription dovetails with liberalism’s emphasis on establishing an agreed international constitutional order. And, yet, the notion of cross-cultural dialogue sits awkwardly with many idealists’ view that they already know right and wrong. For these idealists, the essential task is to shame rights abusers and cajole powerful actors into promoting proper values and holding perpetrators accountable to international (generally Western) standards. As with realism and liberalism, constructivism can be many things to many people.


None of the three theoretical traditions has a strong ability to explain change — a significant weakness in such turbulent times. Realists failed to predict the end of the Cold War, for example. Even after it happened, they tended to assume that the new system would become multipolar (“back to the future,” as the scholar John J. Mearsheimer put it). Likewise, the liberal theory of democratic peace is stronger on what happens after states become democratic than in predicting the timing of democratic transitions, let alone prescribing how to make transitions happen peacefully. Constructivists are good at describing changes in norms and ideas, but they are weak on the material and institutional circumstances necessary to support the emergence of consensus about new values and ideas.

With such uncertain guidance from the theoretical realm, it is no wonder that policymakers, activists, and public commentators fall prey to simplistic or wishful thinking about how to effect change by, say, invading Iraq or setting up an International Criminal Court. In lieu of a good theory of change, the most prudent course is to use the insights of each of the three theoretical traditions as a check on the irrational exuberance of the others. Realists should have to explain whether policies based on calculations of power have sufficient legitimacy to last. Liberals should consider whether nascent democratic institutions can fend off powerful interests that oppose them, or how international institutions can bind a hegemonic power inclined to go its own way. Idealists should be asked about the strategic, institutional, or material conditions in which a set of ideas is likely to take hold.

Theories of international relations claim to explain the way international politics works, but each of the currently prevailing theories falls well short of that goal. One of the principal contributions that international relations theory can make is not predicting the future but providing the vocabulary and conceptual framework to ask hard questions of those who think that changing the world is easy.

Jack Snyder is the Robert and Renée Belfer professor of international relations at Columbia University.

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