Combining a theoretical genealogy and a model for the future, Critical International Theory presents a reflexive agenda for international relations (IR). Its intellectual narrative traces critical theory from its roots to the present, and situates the development of critical theory within the wider ascendance of IR theory since the 1950s. Devetak emphatically seeks to avoid a mere description of its emergence, however; his work first and foremost reappraises the archetypal ideas and theorists in critical IR. It also offers a framework for a “contextualist” mode of historical thought, in contrast to a dialectical–philosophical mode that appeals to a sense of universal reason, or a constructivist mode that interprets history through a given theoretical lens. Differentiating these modes and justifying one strain over another demands understanding the origins of each. The first chapter fixes the beginning of the relevant intellectual history within IR at the dawn of the second “great debate”; conflict between classicists and advocates of a positivist methodology, derived from the natural sciences, planted the seeds of critical theory. Devetak argues that critical theory's stature in the discipline emerged in this era, as the parties to the debate sought to elevate the discipline through theoretical abstraction. Thus, the narrative of this period begins with the methodological disputes (methodenstreit) of the 1950s and closes with the release of Waltz's Theory of International Politics, noting the wide adoption of abstraction and theorizing—even by its opponents. Alongside the classicist perspectives of Hans Morgenthau and Hedley Bull, critical theory became such an opponent to positivism within the broader methodological dispute.