Strauss, Leo, "What Can We Learn from Political Theory?" Review of Politics 69, no. 4 (Fall 2007).  Talk given in July 1942 at the New School for Social Research.

Excerpt:

The title of this lecture is not entirely of my own choosing. I do not like very much the term political theory; I would prefer to speak of political philosophy. Since this terminological question is not entirely verbal, I beg leave to say a few words about it. The term “political theory” implies that there is such a thing as theoretical knowledge of things political.  This implication is by no means self-evident. Formerly, all political knowledge was considered practical knowledge, and not theoretical knowledge. I recall the traditional division of the sciences in to theoretical and practical sciences. According to that division, political philosophy, or political science, together with ethics and economics, belongs to the practical sciences, just as mathematics and the natural sciences belong to the theoretical sciences.  Whoever uses the term “political theory” tacitly denies that traditional distinction. That denial means one of these two things or both of them:) the denial of the distinction between theoretical and practical sciences: all science is ultimately practical (scientia propter otentiam) the basis of all reasonable practice is pure theory. A purely theoretical, detached knowledge of things political is the safest guide for political action, just as a purely theoretical, detached knowledge of things physical is the safest guide toward conquest of nature: this is the view underlying the very term political theory.

Online:
JSTOR