Scarce Differences: Toward a Material and Systemic Foundation for Offensive and Defensive Realism

A divide has opened up between offensive and defensive realism as to the relative scarcity of security in the international system, with powerful implications for the vision each approach offers about the nature of international politics. Yet we still do not understand why the two diverge given their common neorealist foundations. This article reviews implicit, explicit, and other potential explanations of that difference-the relationship between power and security, the offense-defense balance, the prevalence and efficiency of balancing vs. bandwagoning, and the role played by uncertainty in decision-making-and finds them lacking in their ability to provide an adequate account that is systemic and structural in nature, does not violate arguments the scholars have made in practice, and does not confuse cause with effect. Finding prior efforts lacking, this article proposes that the distinction could be logically rooted in material scarcity, a familiar theme in realism historically that has been ignored in more recent formulations. Drawing a distinction between a "dangerous world" in which uncertainty is the core problem and a "competitive world" in which scarcity bedevils state relations helps explain where offensive and defensive realism both diverge and converge.