Why did Hans Morgenthau’s Politics Among Nations become influential after World War II?

Hans Morgenthau’s Politics Among Nations (1948) became highly influential after World War II because it provided a necessary, comprehensive theoretical framework for understanding international relations during a period of global transition.1

Its influence stemmed from several key factors:

• Theoretical Foundation: It established the classical realist approach, which argued that international politics is governed by immutable laws of nature centered on the pursuit of power and the national interest.21
• Response to Idealism: The work emerged as a pragmatic response to [idealism], which had previously emphasized moral and legal constraints on state behavior. Realism offered a more cynical, state-centered view that resonated with the geopolitical realities of the emerging Cold War.1
• Academic Utility: It became one of the most widely used textbooks in the United States and Britain, serving as an essential exposition of realist theory for generations of students and scholars.1

By defining state actions as rational attempts to maintain or increase power, Morgenthau provided a lens for policymakers to navigate an anarchic international system, emphasizing diplomacy and the careful calculation of national capabilities over ideological crusades.21