Chapter 2: Theories of International Relations & Zombies

2.3: Realism

Imagine a world where every state is primarily concerned with its own survival, constantly wary of others. This is the central focus of realism, one of the most influential theories in international relations. Realism emphasizes the competitive and conflictual nature of global politics, operating on the assumption that each state behaves as a unitary actor—a cohesive entity that makes decisions based solely on national interest, without internal divisions or competing interests. Like chess players, states are driven by a desire to accumulate power and secure their interests in a dangerous and anarchic world where no central authority exists to enforce rules or mediate disputes. As a result, realists argue, states are often locked in a struggle for dominance or, at the very least, for survival, and their behavior reflects this constant vigilance.

One of the core pillars of realism is the concept of hard power—the use of military and economic tools by states to influence the behavior of others. Realists argue that in an anarchic international system, where no central authority exists to enforce rules or ensure peace, power becomes the primary currency. As such, states rely on tangible capabilities—troops, tanks, aircraft carriers, and economic leverage—to secure their interests. Hans Morgenthau, one of the founding figures of classical realism, emphasized that international politics is governed by objective laws rooted in human nature, and at the center of those laws is the pursuit of power. In his seminal work Politics Among Nations (1948), Morgenthau argues that political leaders must think and act in terms of national interest defined as power, especially military power, to survive in a competitive international environment. For realists, then, the ability to project hard power isn’t just a policy choice—it’s a necessity for survival and influence on the world stage.

Two notable examples of hard power in action are the 2003 U.S. invasion of Iraq and the international sanctions imposed on Iran. In the case of Iraq, the U.S. justified its military intervention on the grounds that Saddam Hussein’s regime posed a threat to global security due to alleged weapons of mass destruction (WMDs). While the existence of such weapons was later disproven, the operation reflected a realist mindset: removing a perceived threat through overwhelming force to protect national interests and reshape the regional balance of power. This use of direct military force exemplifies hard power’s most visible form—war. In contrast, the campaign of economic sanctions against Iran, particularly those aimed at halting its nuclear program, illustrates a more subtle but still coercive application of hard power. By restricting Iran’s access to global markets and freezing financial assets, the United States and its allies sought to pressure the Iranian government into compliance without firing a single shot. Both cases demonstrate how realism views coercion—whether through bombs or bank freezes—as a necessary tool in a world defined by competition and insecurity.

This focus on power and security can lead to what is known as the security dilemma. The security dilemma occurs when one state’s actions to increase its own security—such as building up its military—make other states feel less secure. This often triggers a cycle of suspicion and arms races. One state’s pursuit of defense is seen by others as a potential threat, so they build up their own forces in response. The Cold War provides a textbook example of this dilemma: the United States and the Soviet Union both expanded their nuclear arsenals out of fear that the other side might gain an advantage. What started as defensive actions by each side eventually spiraled into a full-blown arms race. The security dilemma illustrates how, in the realist world, even efforts to stay safe can make everyone feel less secure.

This brings us to the idea of zero-sum dynamics, another key feature of realism. In a zero-sum game, one side’s gain is always another side’s loss—there’s no room for mutual benefit. Realists argue that international politics often operates in this manner. If one state increases its power, another state inevitably loses relative power. This logic is evident in territorial disputes, where control over land or resources is finite, and one state’s gain comes directly at another’s expense. For example, the ongoing South China Sea dispute pits several nations against each other over control of valuable maritime territory. Any gains in sovereignty or resources by one state result in losses for the others. In such zero-sum situations, compromise or cooperation is difficult because states are inherently focused on maximizing their own gains.

To manage the persistent risk of conflict in international relations, realism emphasizes the importance of maintaining a balance of power. This foundational concept refers to a distribution of capabilities among states in which no single actor becomes powerful enough to dominate all others. In the realist worldview, states are inherently self-interested and exist in a condition of anarchy—without a global authority to enforce rules or guarantee peace. As such, states must constantly assess and respond to the relative power of others. The structure of the international system can take different forms: a unipolar system, where one state holds overwhelming dominance (as the U.S. did after the Cold War); a bipolar system, where two major powers balance each other (as during the U.S.–Soviet rivalry of the Cold War); or a multipolar system, where power is distributed among several states (as in Europe before World War I). Realists argue that regardless of the configuration, states will engage in balancing behaviors—forming alliances, building military capabilities, or pursuing deterrence—to prevent any one actor from becoming too powerful. The goal isn’t necessarily peace, but rather stability through fear and equilibrium, where the risks of aggression are high enough to discourage it.

History offers compelling examples of the balance of power in action, particularly in 19th-century Europe. After the upheaval of the Napoleonic Wars, European states recognized the need to prevent any single power—like Napoleonic France—from overwhelming the continent again. The resulting diplomatic strategy involved a web of shifting alliances among major powers such as Britain, France, Austria, Prussia, and Russia. This approach culminated in the Congress of Vienna in 1815, which aimed to restore equilibrium by reestablishing traditional monarchies and territorial boundaries. Britain, for instance, frequently acted as an offshore balancer, supporting coalitions that opposed whichever continental power seemed most threatening at the time. These maneuvers weren’t driven by ideology or shared values, but by cold calculations of interest and threat—classic realist behavior. The long peace that followed, known as the Concert of Europe, illustrates how a carefully managed balance of power can reduce the likelihood of major war, even among rival states. But that’s all ancient history. How would realism respond if, say, a zombie apocolypse were to break out?!

Realism: Power, Survival, and Keeping Zombies Off Your Lawn

When the dead start rising, don’t expect countries to hold hands and sing “Kumbaya.” At least, that’s what a realist would say! If we view the zombie apocalypse through the lens of realism, the international response would be characterized by a fierce competition for survival. Realists believe the international system is anarchic—there’s no overarching authority to control the actions of states. In a zombie crisis, states would focus on their own survival, securing borders, and amassing military power (including hard power like weapons and secure strongholds) to protect their populations from both zombies and other states. For example, in World War Z, Israel’s decision to build a massive wall around its borders early on is a classic realist move: prioritize national security at all costs, even if it means isolating oneself from global cooperation.

Realists would expect a security dilemma to unfold during a zombie apocalypse, as states prioritize their own survival and view others with suspicion. If one country begins stockpiling military equipment and fortifying its borders to fight zombies, neighboring states might perceive this as a potential threat rather than just a defensive measure. In response, they too would amass weapons and resources—not only to combat the undead but also to prepare for possible opportunistic attacks from rival states. This creates a zero-sum situation, where one state’s increase in security makes others feel less safe, leading to an escalating arms race. As resources like food, medicine, and safe zones become scarce, fear and mistrust could push states toward preemptive invasions, seizing supplies before others have the chance. Instead of uniting against the zombie threat, nations might spiral into conflicts driven by self-preservation, proving that even in the face of an apocalyptic crisis, realists believe states would see each other as their greatest competitors—perhaps even more dangerous than the walking dead themselves.

Realism, with its focus on power, competition, and conflict, offers a straightforward explanation for much of state behavior in international politics. However, it is not without its critics. Some argue that this theory overemphasizes conflict and neglects cooperation, which will be explored in greater depth when we discuss alternative theories like liberalism in the next section. While realism provides a powerful lens for understanding the competitive nature of international relations, it may not fully account for the instances where states do manage to work together for mutual benefit. Nonetheless, understanding realism is crucial for grasping why global politics so often seems like a high-stakes game where survival, not cooperation, is the ultimate prize.