Understanding Realism in International Relations

When India calls for “strategic autonomy” or refuses to take sides in a global conflict, it is reflecting a way of thinking about world politics that is over two thousand years old. That way of thinking is called Realism. Also known as Political Realism or Realpolitik, it is one of the oldest and most influential theories used to explain why states behave the way they do on the world stage. At its core, Realism makes a simple but uncomfortable claim: international politics is a constant struggle for power, and survival matters more than morality. This post explains what Realism is, where it came from, what assumptions hold it together, and why it continues to dominate the study of international relations.

What is Realism? 🔗

Realism is a theoretical framework that views world politics as an ongoing competition among self-interested states, each seeking power and security in a system with no central authority above them. According to this view, states act as rational primary actors navigating a world shaped by power politics and national interest. There is no global government, no world police, and no supreme court that can enforce rules between nations. This condition is called anarchy, and it forms the starting point for almost everything Realists argue.

The most important word to understand here is “anarchy,” but not in the everyday sense of chaos or violence. In international relations, anarchy simply means there is no governing authority above sovereign states. Inside a country, a government makes laws, the police enforce them, and courts punish those who break them. Between countries, no such structure exists. Each state must therefore look after itself, because no higher power will guarantee its safety.

Realists believe the proper job of a scholar or statesman is to study the world as it actually is, not as we wish it could be. They argue that wishing for a peaceful, cooperative world does not make one appear, and that decisions based on idealistic hopes can lead to disaster. For Realists, power and self-interest are the true currency of international affairs, and morality usually takes a back seat.

The historical roots of Realism 🔗

Although Realism became a formal theory only in the twentieth century, its core ideas are ancient. Realists themselves trace their intellectual ancestry back thousands of years, which gives the theory a sense of timeless authority.

Thucydides and the Melian Dialogue 🔗

The earliest and most famous expression of Realist thinking comes from the ancient Greek historian Thucydides, often called the intellectual godfather of Realism. In his History of the Peloponnesian War, he recorded a confrontation between Athens and the small neutral island of Melos in 416 BCE. In this episode, known as the “Melian Dialogue,” the powerful Athenians offered the Melians a stark choice: surrender or be destroyed. The Melians appealed to justice, neutrality, and the gods. The Athenians dismissed these appeals, and when Melos refused to submit, the Athenians invaded, killed the men, and enslaved the women and children.

The dialogue captures the essence of Realism in a single brutal line attributed to the Athenians: the strong do what they can and the weak suffer what they must. This text is studied in nearly every introductory international relations course because it illustrates two competing worldviews, with realism prioritising power and idealism prioritising morality and ethics. It is worth noting, however, that Thucydides himself did not simply endorse Athenian cynicism. After conquering Melos, the overconfident Athenians launched a disastrous campaign against Sicily and ultimately lost the war, suggesting that relying on power alone can be dangerously shortsighted.

Machiavelli and Hobbes 🔗

Centuries later, two more thinkers deepened the Realist tradition. The Italian writer Niccolò Machiavelli emphasised power, survival, and pragmatic statecraft, arguing that rulers must sometimes act ruthlessly to protect the state. The English philosopher Thomas Hobbes contributed the idea of the “state of nature,” a condition without any central authority in which life is insecure and individuals must seek power to survive. Hobbes argued that without a central authority, individuals are compelled to seek power to protect themselves, producing a cycle of fear, mistrust, and pre-emptive aggression. When this logic is applied to nations, it becomes the foundation of the modern Realist worldview.

Realism as a reaction to idealism 🔗

Realism emerged as a distinct school in the twentieth century, largely as a response to idealism (also called liberalism or utopianism). After the horrors of the First World War, many thinkers and statesmen hoped that international law, organisations like the League of Nations, and the spread of democracy could prevent future wars. They believed that cooperation and shared moral values could tame international conflict.

The outbreak of the Second World War shattered this optimism. Realists argued that idealists had ignored the harsh realities of power and had built their hopes on wishful thinking. They insisted that the study of international politics should focus on conflicting national interests rather than abstract principles of peace and justice. The core question dividing the two camps was clear: can international politics be based on a moral order derived from principles of peace and justice, or will it remain the playground of conflicting national interests and power? Realists answered firmly in favour of the second view.

The core assumptions of Realism 🔗

Realism is held together by a set of shared assumptions. While different Realists disagree on details, most accept the following building blocks.

States are the main actors 🔗

For Realists, the state is the most important actor in international politics. While international organisations, corporations, and individuals exist, they are far less significant than sovereign states. Special attention is given to great powers, because they have the most leverage on the international stage. For India, this assumption explains why national governments, not the United Nations, ultimately decide questions of war, trade, and security.

The system is anarchic 🔗

As discussed earlier, the absence of any authority above states forces each country to rely on self-help. Since no one else will protect them, states must build their own strength to survive. This is why nations maintain armies, develop weapons, and form alliances even during peacetime.

States pursue power and national interest 🔗

Realists believe that states are guided above all by the national interest, which is usually defined in terms of power and security. The most influential Realist, Hans Morgenthau, captured this in his famous claim that international politics, like all politics, is a struggle for power. A state’s foreign policy, in this view, should be judged by whether it advances national interest, not by whether it is morally admirable.

Survival comes before morality 🔗

Realists do not deny that morality exists, but they argue that in an anarchic world, survival must come first. Morgenthau argued that human nature remains unchanged and that power is a universal goal in politics, while morality often becomes secondary to the pursuit of power. A leader who sacrifices national security for the sake of ethical purity, a Realist would say, is being naive and irresponsible.

Hans Morgenthau and the six principles 🔗

No discussion of Realism is complete without Hans J. Morgenthau, whose 1948 book Politics Among Nations: The Struggle for Power and Peace turned Realism into a comprehensive theory. The book was a watershed moment in twentieth-century international relations theory and directly shaped American foreign policy for decades.

Morgenthau laid out six principles of political realism. He argued that politics is governed by objective laws rooted in human nature, that the key signpost guiding states is interest defined as power, and that universal moral principles cannot be applied to state actions in their abstract form. One of his most quoted ideas is that the Realist “thinks in terms of interest defined as power,” just as an economist thinks in terms of wealth. This concept of interest defined as power remains the single most important idea in the entire Realist tradition.

Classical Realism versus Neo-Realism 🔗

Over time, Realism split into two major branches. Understanding the difference is essential for any student of the theory.

Classical Realism 🔗

Classical Realism, associated with thinkers like Morgenthau and E.H. Carr, locates the source of conflict in human nature. According to this view, humans are inherently driven by a desire for power, and since states are made up of humans, this lust for power translates into the behaviour of nations. Morgenthau, influenced by Hobbes, placed selfishness and an insatiable human lust for power, which he called animus dominandi, at the centre of his picture of human existence.

Neo-Realism (Structural Realism) 🔗

In 1979, Kenneth Waltz developed Neo-Realism, also called Structural Realism, in his book Theory of International Politics. Waltz shifted the explanation for conflict away from human nature and toward the structure of the international system itself. Neo-realism explains state behaviour by looking at the international system, defined by anarchy and the distribution of power, rather than what happens inside individual states. In other words, states compete for power not because people are wicked, but because the anarchic system gives them no other safe option.

The key difference is straightforward. Classical realists locate the roots of conflict in an imperfect human nature, while neo-realists find the deep causes in the anarchic international system. Neo-Realism later branched further into offensive realism, associated with John Mearsheimer, which holds that states always want more power, and defensive realism, associated with Waltz, which holds that states seek only enough power to feel secure.

The security dilemma 🔗

One of the most important concepts to come out of Realism, especially Neo-Realism, is the security dilemma. It describes how the actions a state takes to protect itself can end up making everyone less safe. When one state builds up its military purely for defence, neighbouring states cannot be sure those forces are defensive, so they arm themselves in response, leaving everyone less secure despite no one wanting conflict.

This idea helps explain arms races and rising tensions in regions across the world, including South Asia. When one country strengthens its defences, its rivals often respond in kind, even when neither side intends to attack. The root of the problem is uncertainty: in an anarchic system, a state can observe another’s capabilities but can never be fully certain of its intentions.

Criticisms of Realism 🔗

Despite its dominance, Realism faces serious criticism. Liberals and constructivists argue that it underestimates the role of cooperation, international law, and shared ideas. Critics of structural realism argue that the involvement of states in international institutions challenges the theory because it fails to recognise the positive relationships that can develop between nations. The growth of bodies like the World Trade Organization and the United Nations, and the everyday cooperation between countries on trade, climate, and health, suggests that the world is not purely a battlefield of competing interests.

Critics also point out that Realism struggles to explain non-state actors such as terrorist networks and multinational corporations, and that its focus on power can become a self-fulfilling prophecy. If leaders assume everyone is a potential enemy, they may behave in ways that create the very hostility they feared.

Why Realism still matters 🔗

Even with these criticisms, Realism remains one of the most influential theories in international relations. Since the Second World War, realism has been considered the most dominant school of thought, and it remains ever-present in twenty-first century politics. Its strength lies in its honest, sometimes harsh, focus on power and survival. When nations build militaries, form strategic partnerships, protect their borders, and put national interest first, they are acting in ways that Realists predicted thousands of years ago. For students trying to make sense of conflict, diplomacy, and the choices states make, Realism offers a powerful starting lens, even if it is not the only one worth looking through.

What do you think? Is the pursuit of national interest and power an unavoidable feature of international politics, or can cooperation and shared values genuinely overcome the logic of anarchy? And when a state’s survival conflicts with its moral principles, which one should ultimately come first?

References

1. https://en.wikipedia.org/wiki/Realism_(international_relations)
2. https://fiveable.me/theories-of-international-relations/unit-1/structural-realism-neorealism/study-guide/h5GEor9aKalY9Wxc
3. https://www.rand.org/pubs/commentary/2025/04/the-realists-grand-experiment.html
4. https://history2705.wordpress.com/thucydides-and-the-melian-dialogue/
5. https://plato.stanford.edu/archives/spr2023/entries/realism-intl-relations/
6. https://objectiveias.in/political-science/classical-realism-n-neo-realism/
7. https://philarchive.org/archive/KORHIR
8. https://www.e-ir.info/2009/07/23/comparing-and-contrasting-classical-realism-and-neo-realism/
9. https://plato.stanford.edu/entries/realism-intl-relations/
10. https://www.ebsco.com/research-starters/social-sciences-and-humanities/morgenthau-advances-realist-school-power-politics
11. https://ondisc.nd.edu/news-media/news/an-introduction-to-realism-in-international-relations/
12. https://www.e-ir.info/2012/01/24/the-differences-between-classical-realism-and-neo-realism/