Dahl’s work of the late 1950s as well as that of the 1960s is characterized by a search for new avenues in the development of reliable knowledge in political science. Although these avenues prove to lead to the same destination, they are quite different in nature. The approach that Dahl took in A Preface, mainly an analytical one, generated a large number of hypotheses on the workings of the American political system that, though perhaps plausible, lack empirical support. In the 1960s, Dahl was to make an effort to fill this gap with empirical research inspired by behavioralism.