ItIs customary to describe the development of political science since the Second World War as a step toward the creation of an empirical science of politics. Not its empiricism, however, but rather its concern for theory is understood to be the defining characteristic of the new way. The prescientific period was also empirically oriented, but it was naive, unthinking empiricism which treated the acquisition of political knowledge as a matter of collecting political facts as one might collect butterflies. Empiricism became scientific, it is said, only when it became theoretical, when its practitioners realized that before they could collect butterflies they had first to fashion a proper net and devise a scheme for ordering the specimens to be caught. At the heart, then, of what we mean today by the science of politics stands political theory, understood as the self-conscious construction of conceptual systems for ordering reality and of hypotheses to explain the interconnections of the parts of these systems. Beside the scientist as survey researcher and statistician stands the scientist as theorist, as author of approaches, frameworks, and models.