Realism is the oldest and most influential paradigm in IR theory. Classical realism (Morgenthau) holds that states are driven by human nature's drive for power; neorealism (Waltz) argues the structure of the international system — specifically its anarchic character and the distribution of power — explains state behavior. Under anarchy, states prioritize survival and relative power gains, making cooperation difficult and conflict recurrent. The balance of power is a central concept: states ally to prevent any single power from achieving hegemony. Offensive realism (Mearsheimer) argues states seek to maximize power; defensive realism holds states seek sufficient security rather than maximum power.
Apply realist logic to historical cases: the alliance patterns before WWI, US containment policy during the Cold War, China's military buildup today. Evaluate where realism succeeds and where it fails to predict or explain outcomes.
From your introduction to international relations, you learned that the international system has no overarching authority — no world government that can enforce agreements or protect states from one another. Realism begins exactly there. If no one can guarantee your security, you must guarantee it yourself. This single premise — anarchy as the defining condition of world politics — is where realist logic starts and from which most of its other claims flow.
Classical realists like Hans Morgenthau grounded this in human nature: leaders pursue power because people, and by extension states, are inherently self-interested and competitive. Kenneth Waltz's neorealism shifted the explanation from human nature to system structure. For Waltz, it doesn't matter whether individual leaders are peaceful or aggressive — the structure of anarchy compels all states to behave similarly. A state that neglects its security will not survive. States are therefore "socialized" by the system into self-help behavior regardless of their domestic politics or values. This is a powerful move: it means you can predict state behavior without knowing much about internal politics.
From this structural logic flows the concept of the balance of power. Under anarchy, any state that grows too powerful threatens all others, because no one can be certain of its intentions and there is no referee to stop it. Rational states therefore balance against rising powers — forming alliances, building up their own military, and checking potential hegemons. This explains why Napoleon's France, Hitler's Germany, and potentially today's rising China all trigger coalition formation by neighboring states regardless of ideology. Offensive realism (Mearsheimer) pushes this further: because no state can ever be sure of another's intentions, the safest strategy is to maximize power relative to rivals. Defensive realism responds that this leads to counterproductive arms races; states should seek "enough" security, not maximum power.
The practical implication is that international institutions and international law, while not meaningless, are weak constraints on state behavior when core security interests are at stake. States cooperate when their interests align and defect when they don't — alliances are marriages of convenience, not commitments of principle. This is why realists were skeptical of NATO expansion, the liberal peace project, and rule-based international order: when the distribution of power shifts, the rules change with it. Realism is not a counsel of despair but a demand for clear-eyed analysis: understand the structure of power before counting on norms.
Topics in reflective domains aren't scored by quiz answers. Read, reflect, and mark when you've thought it through.