Theories of International Relations

In October 1962, the United States and the Soviet Union came within hours of nuclear war over missiles in Cuba. Two totally different schools of thought have spent decades arguing about why that crisis ended peacefully — and why nations go to war or cooperate at all. Understanding those schools of thought is how diplomats, analysts, and policymakers make sense of a chaotic world.

- The core claims of Realism, Liberalism, and Constructivism - How each theory would explain the same historical event differently - Key vocabulary: anarchy, sovereignty, balance of power, interdependence - How to analyze a current event through more than one theoretical lens

Realism, associated with thinkers like Hans Morgenthau and later Kenneth Waltz, argues that the international system is anarchic — meaning there is no world government or higher authority forcing states to behave. Because of this, Realists argue every state's top priority is survival, and states build military power and alliances to protect themselves, a concept called 'balance of power.' A Realist reading of the Cuban Missile Crisis says the USSR placed missiles in Cuba to balance against U.S. missiles already stationed in Turkey, and the crisis ended because both superpowers rationally calculated that nuclear war served no one's survival.

Liberalism, developed by scholars like Robert Keohane and Joseph Nye, disagrees that states are doomed to endless competition. Liberals argue that trade, international institutions (like the United Nations or NATO), and economic interdependence give states strong incentives to cooperate rather than fight, because war becomes too costly for everyone's economy. A Liberal analysis of the Cold War's end points to growing trade ties and international agreements (like arms-control treaties) as key reasons tensions eventually eased — not just military calculation.

Constructivism, championed by Alexander Wendt, argues that international politics isn't just about raw power or economics — it's shaped by ideas, identities, and shared beliefs. Wendt's famous phrase is 'anarchy is what states make of it,' meaning the same anarchic system can lead to war or peace depending on how states view each other (as enemies or partners). A Constructivist would point out that the U.S. doesn't fear British nuclear weapons the way it fears North Korean ones, even though both are technically threats — because of the different identities and relationships involved.