Neorealism, also called structural realism, is most closely associated with Kenneth Waltz's Theory of International Politics (1979). It reframed classical realism by locating the cause of state behavior in the structure of the international system rather than in human nature or domestic politics, as Hans Morgenthau had emphasized.
Waltz argued that the international system has three defining features: it is anarchic (no central authority above states), its units (states) are functionally similar in that they all must provide for their own security, and they differ mainly in the distribution of capabilities among them. Because no world government can enforce agreements, states operate in a self-help system where survival is the primary goal and relative power matters more than absolute gains.
From these premises neorealists derive several expectations: states balance against concentrations of power, alliances are temporary and interest-based, and cooperation is difficult because of cheating and relative-gains concerns. Waltz also argued that bipolar systems (like the Cold War) tend to be more stable than multipolar ones because uncertainty and miscalculation are reduced.
The school later split into two main branches:
- Defensive realism (Waltz, Stephen Van Evera, Charles Glaser): states seek an appropriate amount of power; excessive expansion provokes balancing and is self-defeating.
- Offensive realism (John Mearsheimer, The Tragedy of Great Power Politics, 2001): states maximize relative power and aspire to regional hegemony because intentions can never be known with certainty.
Neorealism has been criticized for underexplaining change (the peaceful end of the Cold War surprised most neorealists), downplaying domestic politics and ideology, and treating states as undifferentiated "billiard balls." Constructivists like Alexander Wendt countered that "anarchy is what states make of it," while liberal institutionalists such as Robert Keohane argue that institutions can mitigate the effects neorealism predicts.
Example
Neorealists pointed to NATO's eastward enlargement after 1999 as a predictable trigger for Russian balancing behavior, an argument John Mearsheimer made repeatedly regarding Ukraine from 2014 onward.
Frequently asked questions
Classical realism (e.g., Morgenthau) traces conflict to human nature and the lust for power; neorealism locates the cause in the anarchic structure of the system, which compels even benign states to compete for security.
Keep learning