This article draws on Hobbes and existentialist philosophy to contend that anxiety needs to be integrated into international relations (IR) theory as a constitutive condition, and proposes theoretical avenues for doing so. While IR scholars routinely base their assumptions regarding the centrality of fear and self-help behavior on the Hobbesian state of nature, they overlook the Hobbesian emphasis on anxiety as the human condition that gives rise to the state of nature. The first section of the article turns to existentialist philosophy to explicate anxiety's relation to fear, multiple forms, and link to agency. The second section draws on some recent interpretations to outline the role that anxiety plays in Hobbesian thought. Finally, I argue that an ontological security (OS) perspective that is enriched by insights from existentialism provides the most appropriate theoretical venue for integrating anxiety into IR theory and discuss the contributions of this approach to OS studies and IR theory.
