Hans Morgenthau is the intellectual father of postwar realism and arguably the most important international relations theorist of his generation. His textbook went through six editions, one of them posthumous, and was almost universally read by undergraduate and graduate students of international relations over a span of three decades. Because of Morgenthau, realism became the dominant paradigm in the field and maintained this position throughout the Cold War. In the 1980s, neorealism gained wide currency, and graduate students increasingly read Kenneth Waltz in lieu of Morgenthau as their introduction to the study of international relations. In the aftermath of the Cold War, scholars interested in power and its consequences are looking to more traditional forms of realism for insights. Morgenthau and his ideas are once again timely and need to be put into historical and intellectual context for a new generation of readers.

Like Thucydides and Clausewitz, Morgenthau has been misinterpreted. Critics misread his insistence on the enduring and central importance of power in all political relationships as an endorsement of European-style Realpolitik and its axiom that might makes right.