Chapter 2: Theories of International Relations & Zombies

2.2: Theory

At its core, a theoryy is a structured explanation or model that helps us make sense of complex phenomena by identifying patterns, causes, and relationships. Think of a theory as a mental map—it doesn’t recreate the world in perfect detail, but it offers enough guidance to navigate it intelligently. In international relations, theories serve as frameworks that help scholars and policymakers understand why states behave the way they do, how conflicts arise, and what might foster cooperation. A hypothesis, by contrast, is a specific, testable proposition often derived from a theory. For example, if Realist theory emphasizes power and survival, a hypothesis might propose that “states with increasing military capabilities are more likely to initiate conflict.” In short, theories are the big-picture lenses; hypotheses are the zoom-ins.

You’ve probably heard someone dismiss an idea by saying it’s “just a theory.” But in the academic world—especially in political science and international relations—that phrase makes scholars wince. Theories are not wild guesses or untested whims. They’re rigorously developed, debated, and often supported by decades of empirical observation and historical study. Kenneth Waltz’s Theory of International Politics (1979), for instance, reshaped the field by introducing structural realism, which remains a foundational theory even when people disagree with it. Theories can be revised or even replaced, but they’re far from arbitrary—they’re essential tools for making sense of a world that often seems chaotic.

Compared to other branches of political science, international relations leans heavily on theory. Why? Because IR deals with a uniquely anarchic environment—there’s no global government enforcing rules the way national governments do within states. This lack of central authority makes outcomes harder to predict and more reliant on theoretical interpretation. Without theory, we’d just have a long list of facts—wars, treaties, trade deals—with no way to connect the dots. As we move into the next section, we’ll explore six major IR theories that have each shaped the way scholars and policymakers think about global politics. Each offers a different lens—sometimes overlapping, sometimes clashing—but all are valuable in understanding the global stage and the drama that plays out on it.