In a few days, students in the United States will return to university, and thousands of them will enroll in international relations (IR) courses. They will be instructed on the major theories of IR, like realism, liberalism, and constructivism. Unfortunately, for them and for the discipline, one of those theories is increasingly unhelpful for understanding how global affairs really work.
Perhaps ironically, realism has become unrealistic.
Prominent realists have emerged as outspoken critics of U.S. foreign policy, arguing that Washington should pursue a less ambitious, more restrained approach to the world. Yet this theoretical approach has become unsustainable. If, for decade after decade, the world’s most powerful country is not behaving the way that realist theory predicts, then at a certain point, it is the theory—rather than Washington—that needs to change.
International relations is a type of social science. Social sciences, like economics, political science, psychology, sociology, and anthropology, attempt to explain how the social world works. Specifically, IR seeks to explain conflict and cooperation among nation-states. This is, in social science jargon, the dependent variable—the outcome to be explained. Why do states cooperate? They engage in international trade and investment, form alliances, and transfer arms. And why do states sometimes come into conflict? They issue demarches, sanction each other’s economies, and, at the extreme, fight wars.
The major IR theories differ primarily in terms of—to return to scientific jargon—their preferred independent variables. These are the most important causes or driving forces. Realists believe that power, especially military power, is the central driving force. Liberals believe that a triumvirate of independent variables (international institutions, economic interdependence, and democracy) facilitates international cooperation. And constructivists hold that ideas, especially norms and identities, shape patterns of conflict and cooperation.
Philosophers of science, like Karl Popper and Imre Lakatos, have explained how social scientists should develop theories that can account for empirical realities. When there are many empirical anomalies that a theory cannot explain, then that theory needs to be revised or discarded in favor of a theory that can better make sense of the empirical world.
Liberals and constructivists are, for the most part, following the scientific method and developing theories to effectively explain international relations. Liberal scholars, for example, have documented how international institutions, like the World Trade Organization, can reduce transaction costs and facilitate international trade. Constructivists have shown how norm entrepreneurs have persuaded powerful states to sign and comply with human rights treaties. The list goes so on.
Classical realism, the body of realist tradition tracing back to the ancient world, also sheds much light on global affairs. Classical realist thinkers, like Thucydides, Niccolo Machiavelli, Hans Morgenthau, and Henry Kissinger taught us that the world is a dangerous place and that competition and conflict among the major powers is a natural and enduring part of politics among nations. States protect themselves by building military power. Since all states want to dominate, but none want to be dominated, a balance of power tends to form that provides a measure of global stability.
The modern variants of realism, so-called neorealism, however, have proved to be a poor guide to understanding the real world.
Naturally, one key task for any IR scholar is to explain the behavior of the United States—the most powerful country in the world over the past century. After World War II, Washington and its allies sought to build a liberal international order, predicated on strong alliances in Europe and Asia, as well as cooperation through international institutions, free trade, democracy and human rights.
This effort was deepened and expanded after the end of the Cold War. Countries previously locked behind the Iron Curtain were welcomed into the free world and NATO expanded. Many countries in the global south adopted free-market democracy as the only legitimate political and economic system.
That was not what realists expected. On grand strategy, many realists argued that the United States, protected by oceans, friendly neighbors, and nuclear weapons, would not need a globally engaged foreign policy. Realists argued that Washington should pursue a grand strategy of restraint and offshore balancing. It could mind its own business in the Western Hemisphere, and if a hostile rival, like China, threatened to overturn a regional balance, then it could intervene from offshore to restore the balance of power. Instead, as realists themselves have lamented, Washington pursued a grand strategy of liberal hegemony.
On Europe and NATO, realists argued that, with the Cold War over, Washington would come home and rivalry would return among Western European powers. Instead, Washington doubled down on its commitment to Europe and pursued a policy of NATO enlargement.
Realists predicted that the United States would only need a minimal and secure second-strike nuclear deterrent. Instead, Washington built thousands of nuclear weapons and missile defenses, and it strived for nuclear superiority over rivals.
Realists argued that using extreme measures, like military force, to stop the spread of nuclear weapons and counter terrorism was too costly. Instead, Washington did just that.
They argued that it would be counterproductive to support vulnerable front-line states, like Taiwan, Israel, and Ukraine. Once again, Washington did the opposite.
They argued that Washington should not worry about the credibility of its commitments. In defiance of the theorists, Washington used military force with the explicit goal of upholding the credibility of its commitments.
In short, the standard-bearers of the realist movement have gotten wrong almost every theoretical prediction about the behavior of the most important great-power nation in the history of the world. For a theory that claims to excel in explaining the security policies of great powers, this is a fatal indictment.
Instead of revising their theories, realists simply insisted that the world was at fault. According to many realists, the last 80 (or at least 35 years) of U.S. foreign policy have been one big, costly mistake. In his 2018 book, The Great Delusion: Liberal Dreams and International Realities, realist scholar John Mearsheimer argues that:
It is widely believed in the West that the United States should spread liberal democracy across the world, foster an open international economy, and build international institutions. The policy of remaking the world in America’s image is supposed to protect human rights, promote peace, and make the world safe for democracy. But this is not what has happened. Instead, the United States has become a highly militarized state fighting wars that undermine peace, harm human rights, and threaten liberal values at home.
What about the U.S. policy of building a robust nuclear arsenal to extend deterrence to its more than 30 treaty allies? That is also a mistake. In a recent Foreign Policy column, for example, Stephen Walt argued that Washington’s large nuclear arsenal “makes no sense.”
What about the U.S. policy of NATO enlargement since the end of the Cold War? Reckless. The close U.S. security partnership with Israel? A strategic liability. Supporting Ukraine? Remarkably foolish.
A formulaic, color-by-number agenda for realist research has emerged: identify a central pillar of the U.S. bipartisan foreign-policy consensus; design a study, often just a small number of qualitative case studies, to prove that Washington is doing it wrong; conclude that it would be better if Washington followed realist principles instead. This is ideology masquerading as social science.
As a result, realist theory today falls between two stools. Academic political scientists, of the sort who publish research articles in journals like the American Political Science Review, do not take this branch of realist scholarship seriously but nonetheless assume that it has an important impact on public-policy debates in Washington. Yet in Washington, policymakers have long ignored realists’ unrealistic policy recommendations, continuing, for example, to support Ukraine and Taiwan and a robust nuclear posture. But these policymakers still assume that, however impractical, realists must be making important theoretical contributions within the realm of academia.
In fact, by trying to be both scholarly and policy-relevant, realists are doing neither. They have instead become like physicists angrily insisting that airplanes should not fly.
Power, especially military power, is an important force in world affairs. Scholars who believe that should update and revise realist theory so that they may educate—rather than gaslight—the next generation of curious students.
