  In spite of its ambiguities and weaknesses, Morgenthau’s Politics among Nations became a standard textbook and influenced thinking about international politics for a generation or so. At the same time, there was an attempt to develop a more methodologically rigorous approach to theorizing about international affairs. In the 1950s and 1960s a large influx of scientists from different fields entered the discipline of International Relations and attempted to replace the “wisdom literature” of classical realists with scientific concepts and reasoning (Brown 35). This in turn provoked a counterattack by Morgenthau and scholars associated with the so-called English School, especially Hedley Bull, who defended a traditional approach (Bull 1966).