Realism (international relations)

Based on Wikipedia: Realism (international relations)

The World Is a Dangerous Place, and Everyone Knows It

Here's an uncomfortable truth that most politicians won't say out loud but nearly all of them believe: the international system is essentially a jungle. There's no world government, no global police force, no impartial referee. When push comes to shove, every nation is on its own.

This isn't cynicism. It's the foundation of what scholars call "realism" in international relations—the oldest and arguably most influential way of understanding why countries behave the way they do.

Realism starts with a simple observation: the world has no supreme authority. The United Nations can pass resolutions, but it can't force a powerful country to comply. International law exists, but there's no world court with the power to enforce its rulings against nations that refuse to show up. This absence of higher authority is what political scientists call "anarchy"—not chaos, but the absence of a ruler above the rulers.

In this environment, realists argue, states behave like rival firms in an unregulated market. They compete for advantage. They eye each other warily. They make alliances when convenient and break them when necessary. And above all, they accumulate power—because in a world where no one else will protect you, power is the only reliable guarantee of survival.

The Ancient Roots of a Modern Theory

Realism isn't a twentieth-century invention. Its intellectual roots stretch back over two thousand years to an Athenian general named Thucydides, who wrote the definitive account of the Peloponnesian War between Athens and Sparta in the fifth century before the common era.

Thucydides recorded a chilling exchange known as the Melian Dialogue. The powerful Athenians arrived at the small island of Melos and demanded surrender. The Melians appealed to justice, to the gods, to international norms. The Athenians replied with what became the founding statement of realist thought: "The strong do what they can, and the weak suffer what they must."

The Melians refused to surrender. Athens conquered them anyway, killed all the men, and enslaved the women and children.

Brutal? Absolutely. But Thucydides wasn't celebrating this outcome—he was documenting how power actually works when the stakes are high enough. His lesson echoed through the centuries.

In Renaissance Italy, Niccolò Machiavelli advised princes that it was better to be feared than loved, because fear is more reliable. In seventeenth-century England, Thomas Hobbes described the natural state of humanity as "a war of all against all," where life was "solitary, poor, nasty, brutish, and short." In Prussia, Carl von Clausewitz—the great military theorist—declared that war was simply "the continuation of politics by other means."

These thinkers shared a conviction that moral ideals, however noble, couldn't override the basic dynamics of power and self-interest that govern relations between states.

The Security Dilemma: Why Good Intentions Make Things Worse

One of realism's most troubling insights is something called the security dilemma. It explains why even peaceful nations can end up in arms races and wars—not because anyone wants conflict, but because of the logic of the situation itself.

Imagine two neighboring countries, neither of which wants war. But both are nervous. Country A decides to build up its military—purely for defense, purely because you can never be too careful. Country B notices this buildup. From B's perspective, how can they be sure A's intentions are peaceful? They can't read minds. So B builds up its own forces, just to be safe.

Now A sees B arming itself and thinks: "We were right to be worried. They're clearly preparing for something." So A accelerates its military spending. B responds in kind. Before long, both countries are heavily armed, deeply suspicious, and far less secure than when they started—even though neither wanted this outcome.

This is the security dilemma in action. It's why realists are skeptical of arms control agreements and international institutions. Even when everyone has good intentions, the structure of the international system—anarchic, uncertain, self-help—pushes states toward competition.

The Cold War provides the clearest example. The United States and the Soviet Union spent four decades amassing enough nuclear weapons to destroy human civilization several times over. Was this rational? In the narrow sense of realism, yes. Each side feared the other. Neither could be certain of the other's intentions. So both kept building, creating the terrifying stability of Mutually Assured Destruction—aptly abbreviated as M.A.D.

What Realism Is Not

Realism is often confused with cynicism, with warmongering, with the belief that might makes right. But this misunderstands what realists are actually claiming.

Realism is a descriptive theory, not a moral prescription. When a realist says states pursue power, they're not saying states should pursue power—they're saying this is what states actually do, whether we like it or not. Understanding this behavior is the first step toward managing it.

Consider a doctor diagnosing a disease. The doctor isn't endorsing the disease by describing how it works. They're trying to understand it so they can treat it. Realists make a similar argument: if you want peace, you need to understand war. If you want cooperation, you need to understand why competition is the default.

Realism also differs from the related concept of Realpolitik—a German term that roughly translates to "practical politics." Realpolitik is a prescriptive approach to statecraft: it tells leaders how to act pragmatically in pursuit of national interests. Realism is broader. It's an entire framework for analyzing international relations, one that can inform policy but isn't itself a policy.

Some realists are quite dovish. They oppose foreign interventions, military adventures, and attempts at nation-building—not because they're pacifists, but because such actions often backfire and waste power that could be better preserved. Other realists are hawkish, advocating for military strength as the best guarantee of peace. The theory itself is neutral on these questions.

Liberalism: The Great Rival

To understand realism fully, you need to understand what it argues against. Its primary intellectual opponent is liberalism in international relations—not to be confused with the liberal or progressive label in domestic politics.

Liberal international relations theory holds that cooperation between states is possible and sustainable. Liberals point to international institutions like the World Trade Organization, the International Monetary Fund, and the European Union as evidence that nations can bind themselves to rules and benefit from doing so. They argue that democracies rarely fight each other—the so-called "democratic peace"—and that economic interdependence creates incentives for peaceful behavior.

For liberals, the anarchic international system isn't destiny. It's a problem to be solved through institution-building, free trade, and the spread of democratic governance. Woodrow Wilson, the American president who championed the League of Nations after World War One, represents the high point of liberal internationalism. His vision was of a world where nations would resolve disputes through collective security rather than balance-of-power politics.

Realists view this as dangerously naive.

They point out that the League of Nations collapsed utterly in the face of fascist aggression in the nineteen-thirties. International institutions, realists argue, only work when powerful states want them to work. When vital interests are at stake, nations abandon institutional constraints without hesitation. The United Nations Security Council, for instance, is routinely paralyzed by vetoes from its permanent members—precisely because those members won't accept constraints on their own behavior.

The liberal response is that international cooperation has nonetheless grown deeper and more durable over time, that trade and democracy have indeed reduced conflict, and that realism's pessimism is self-fulfilling. If leaders expect conflict, they prepare for conflict, and their preparations make conflict more likely.

This debate remains unresolved. Every major event in international relations—the end of the Cold War, the expansion of the North Atlantic Treaty Organization (NATO), the rise of China, the war in Ukraine—gets interpreted through both lenses, with each side claiming vindication.

The Different Schools of Realist Thought

Realism isn't a single unified theory. It's a family of related approaches that share core assumptions but diverge on crucial details.

Classical realism, associated with thinkers like Hans Morgenthau and Reinhold Niebuhr, locates the source of international conflict in human nature itself. Humans are inherently self-interested, power-seeking creatures. States, being composed of humans and led by humans, inherit these qualities. Competition and conflict are therefore inevitable, rooted in the fundamental drives of the species.

Morgenthau, a German-Jewish refugee from Nazi persecution, brought this perspective to America in the nineteen-forties. His book "Politics Among Nations" became the founding text of American realism, shaping a generation of diplomats and scholars. His view was deeply influenced by his experience of European collapse—the failure of the League of Nations, the rise of totalitarianism, the catastrophe of World War Two. Idealism, he concluded, was a luxury that got people killed.

Neorealism—sometimes called structural realism—emerged in the nineteen-seventies, primarily through the work of Kenneth Waltz. Waltz argued that human nature was beside the point. What mattered was the structure of the international system itself.

Think of it this way: even if every state were led by angels, the anarchic system would still push them toward competition. With no higher authority to enforce agreements or punish aggression, every state must worry about its own security. This structural pressure, not human wickedness, explains why states behave the way they do.

Neorealism was more "scientific" than classical realism—it sought to explain international politics through abstract structural variables rather than historical narratives or assumptions about human nature. This made it more rigorous but also more abstract and, critics argued, less attuned to the actual complexity of foreign policy decisions.

Within neorealism, a further split emerged between defensive realists and offensive realists.

Defensive realists, like Waltz himself and Stephen Walt, argue that states primarily seek security, not power for its own sake. Expansion is usually counterproductive because it triggers balancing coalitions. Smart states therefore maintain enough power to defend themselves but avoid the costs and risks of aggressive expansion.

Offensive realists, led by John Mearsheimer, take a darker view. They argue that states can never be certain of each other's intentions, and the only way to guarantee survival is to become so powerful that no one can threaten you. This drives great powers toward hegemony—dominance of the international system. The logical endpoint of offensive realism is a world where great powers constantly compete for supremacy, with conflict always lurking on the horizon.

Mearsheimer's analysis of China's rise follows this logic. As China becomes more powerful, he argues, it will inevitably challenge American dominance in Asia—not because Chinese leaders are evil, but because the logic of great power politics compels rising powers to seek regional hegemony. The United States, following the same logic, will inevitably resist. Conflict, in some form, is therefore highly likely.

Neoclassical Realism: Bringing Everything Together

The newest strand of realist thought, neoclassical realism, attempts to synthesize classical and neorealist insights while addressing their limitations.

Named by scholar Gideon Rose in the nineteen-nineties, neoclassical realism accepts that the structure of the international system matters—the neorealist insight—but argues that structure alone can't explain foreign policy. States face the same systemic pressures but respond differently. Why?

Because domestic factors intervene between systemic pressures and policy outcomes. The nature of a state's government, its political culture, the beliefs of its leaders, the influence of interest groups—all these factors shape how states perceive and respond to the international environment.

Consider how different democracies and autocracies might respond to the same threat. Or how a state with a recent history of invasion might be more security-conscious than one that feels geographically protected. Neoclassical realism provides tools for analyzing these variations.

This approach is more complicated than pure neorealism, but arguably more useful for understanding actual events. It acknowledges that leaders matter, that perceptions matter, that domestic politics matter—without abandoning the core realist insight that power and security remain the fundamental currency of international relations.

The Liberal Realist Compromise

Not all scholars accept the sharp division between realism and liberalism. The English School, developed primarily by British scholars like Hedley Bull, offers a middle path.

Bull's influential work "The Anarchical Society," published in nineteen seventy-seven, argues that the international system is indeed anarchic—there's no world government—but this doesn't mean it's lawless chaos. States have developed what Bull calls an "international society": shared norms, rules, and institutions that create order even without enforcement.

This society includes diplomacy, international law, the balance of power, and great power management. These mechanisms don't eliminate conflict, but they constrain and channel it. Wars still happen, but they typically follow certain rules. Treaties get broken, but they also get kept—far more often than pure realism would predict.

The English School suggests that realists and liberals are both partly right. The international system is competitive and dangerous, but it's not simply a war of all against all. Norms and institutions matter, even if they're not as decisive as liberals hope.

America's Endless Debate

The tension between realism and liberal internationalism has defined American foreign policy debates for over a century.

The Founding Fathers were essentially realists. George Washington warned against "entangling alliances" and foreign adventures. John Quincy Adams declared that America "goes not abroad in search of monsters to destroy." The early republic focused on continental expansion and staying out of European power politics.

Woodrow Wilson changed everything. After World War One, he championed a new world order based on collective security, self-determination, and international law. His vision was rejected by the Senate, which refused to join the League of Nations, but Wilsonian idealism became a permanent strand of American foreign policy thinking.

Franklin Roosevelt and Harry Truman built the post-World War Two order—the United Nations, the International Monetary Fund, the General Agreement on Tariffs and Trade, NATO—that embodied liberal internationalist principles while being shaped by realist power calculations. America would lead the "free world" against Soviet communism, but it would do so through multilateral institutions that bound allies together and legitimized American leadership.

The Cold War's end in nineteen eighty-nine unleashed a new wave of liberal optimism. With the Soviet threat gone, some argued that history had ended—democracy and capitalism had won, and the spread of these systems would gradually eliminate great power conflict. The nineteen-nineties saw American interventions in Somalia, Haiti, Bosnia, and Kosovo, justified in humanitarian terms that would have made Wilson proud.

Realists pushed back. George Kennan, the architect of Cold War containment strategy, opposed NATO expansion into Eastern Europe, warning that it would provoke Russia without adding meaningful security. Other realists opposed the two thousand three invasion of Iraq, arguing that it was based on faulty threat assessments and would destabilize the region. John Mearsheimer and Stephen Walt became prominent critics of American foreign policy, arguing that liberal adventurism was wasting American power and creating unnecessary enemies.

The debate continues today. Is China a revisionist power that must be contained, or a potential partner that can be integrated into the liberal international order? Should America maintain its global alliance network, or retrench to focus on core interests? Is promoting democracy abroad a vital interest or a dangerous distraction?

Realists and liberals give different answers to these questions—and whoever wins the argument shapes the policies that follow.

What Realism Gets Wrong

For all its influence, realism has significant blind spots that its critics are eager to highlight.

First, realism struggles to explain change. If the international system is structurally anarchic and states are driven by eternal security concerns, why has the world changed so dramatically over time? Why don't democracies fight each other? Why has Western Europe, historically the most war-torn region on earth, been peaceful for eighty years? Why has outright conquest become rare?

Liberals argue that these changes reflect the growing influence of institutions, norms, and economic interdependence—factors that realism systematically downplays.

Second, realism treats states as unified rational actors—"black boxes" or "billiard balls" that respond predictably to external pressures. But states are complex entities with multiple, often conflicting interests. Domestic politics, bureaucratic competition, and individual leadership all shape foreign policy in ways that pure structural analysis misses.

Third, realism focuses almost exclusively on great powers and military security. But much of international politics involves economics, the environment, public health, migration, and other issues that don't fit neatly into the power-and-security framework. The global response to climate change, for instance, can't be understood purely through a realist lens.

Fourth, realism has a questionable predictive record. Realists predicted that the end of the Cold War would lead to renewed great power competition in Europe and the collapse of NATO. Instead, Europe integrated further and NATO expanded. Realists expected rising powers like China to immediately challenge the existing order. Instead, China spent decades integrating into that order and benefiting from it.

Defenders of realism respond that the theory is meant to explain long-term tendencies, not short-term events. The peaceful decades after the Cold War, they argue, were an anomaly enabled by American dominance. As that dominance fades, realist predictions are being vindicated: great power competition is returning, institutions are weakening, and the liberal order is under strain.

Why Realism Persists

Despite its limitations, realism endures for a simple reason: it captures something important about how the world actually works.

When crises hit, states still reach for power. When vital interests are threatened, states still ignore international law. When push comes to shove, states still prioritize their own survival over abstract principles. The invasion of Ukraine in two thousand twenty-two, the rising tensions between the United States and China, the collapse of arms control agreements—all these developments seem to vindicate the realist worldview.

Realism also appeals because it's modest about what can be achieved. It doesn't promise utopia. It doesn't claim that the right institutions or the right policies will eliminate conflict. It offers a sober assessment of human limitations and counsels prudence rather than crusading.

For policymakers navigating a dangerous world, this modesty can be valuable. Better to be prepared for conflict and wrong than to assume peace and be caught off guard.

Whether you find realism convincing or disturbing—or both—understanding it is essential. Its assumptions shape how governments think about national security, how diplomats negotiate treaties, and how analysts assess threats. When a president talks about "national interests" or a general discusses "the balance of power," they're speaking the language of realism, whether they know it or not.

The theory that began with Thucydides watching Athens and Sparta tear the Greek world apart remains, twenty-five centuries later, one of the most powerful frameworks we have for understanding why nations do what they do. The strong do what they can. The weak suffer what they must. And everyone, strong and weak alike, keeps a wary eye on everyone else.