“Anarchy,” as conceptualized by John J. Mearsheimer, refers to the absence of a central authority governing the international system. This lack of overarching governance leads to a self-help world where states, acting as rational actors, must rely primarily on their own resources and strategies for survival. Mearsheimer uses the concept of anarchy to explain why international politics is inherently competitive and conflict-prone, as states cannot depend on any higher authority for their security. In The Tragedy of Great Power Politics, anarchy is not just a structural feature of the international system but a driving force that compels states to constantly assess and respond to the power dynamics around them, often through power accumulation and strategic alliances.

“Balance of power” is a term used to describe the distribution of military and economic power among states in the international system. Mearsheimer contends that states, especially great powers, continuously adjust their strategies to prevent any single state from achieving dominance, leading to a shifting balance of power. This concept is a key driver of state behavior in his analysis of international relations.