What do you mean by offensive and defensive realism?

Shared ground

• Both follow Kenneth Waltz’s third-image start: the international system is anarchic. There is no world government.
• Survival is the first goal. Intentions of others are uncertain. Capabilities matter more than speeches.
• The security dilemma, developed by John Herz and Robert Jervis, is the shared mechanism: steps that one State takes to be safe can look like threats to another.

Defensive realism

• Waltz’s Theory of International Politics is the main defensive text. States seek enough power to be secure, not maximum power.
• Excess power triggers balancing. Conquest is often self-defeating because of nationalism, nuclear weapons, and the costs of occupation.
• Stephen Walt’s balance-of-threat and Jervis’s offence-defence balance sit in this family: moderation can be rational.
• Stability is more likely when defence is easy and when great powers accept a balance.

Offensive realism

• John Mearsheimer’s The Tragedy of Great Power Politics holds that great powers seek regional hegemony and as much power as they can get, because only hegemony ends the survival problem.
• The structure creates revisionist behaviour even among status-quo-minded leaders. Buck-passing and war are expected tools.
• Offshore balancers, in this view, try to stop a peer hegemon in another region, which is how Mearsheimer reads United States policy toward potential Asian hegemons.

Distinction that matters

• Defensive realism predicts more restraint and more balancing against expansion. Offensive realism predicts more expansion and more tragedy.
• Neither is Keohane’s institutionalism. Institutions, for both realisms, are thin. For Keohane they can still shape cheating and information.
• India’s nuclear and Quad choices can be read in both frames: minimum deterrence looks defensive; concern to prevent Chinese regional hegemony looks closer to Mearsheimer’s problem.