In this paper an analysis of Hobbes' argument in favor of the Leviathan is combined with a reassessment in a new security environment. The analysis shows that Hobbes' premises are complex and lead to conclusions that differ from the realist as well as from the world-state position, both attributed to Hobbesian logic in IR theory. A strict application of the Hobbesian argument in today's security context leads to a rationale of multilateral institution-building among states. In the first part of the paper the internationalist analogy in the concept of war of all against all is uncovered and analyzed in relation to the security dilemma, domestic analogy, and methodological individualism. The second part reassesses the Hobbesian security rationale in a security environment which is assumed to be shaped by transnational terrorism and nuclear WMD.