An entire generation of political scientists trained in the field of comparative politics with a Latin American specialization grew up reading the Thesis, as it was called (Kling 1956). I know: I am part of that generation. I first read Kling's piece as an undergraduate enrolled in the only Latin American politics course that was offered (rather irregularly, I should add) at my institution. I recall the piece to this day because it made such a strong impression on me, being, as it was, in such sharp contrast to so much of the scholarship of the period. Re-reading it today gives us surprising insight into the epistemological battles of Kling's day. First, a brief background about the author of this highly cited paper. I never had the honor of meeting Kling, but a little digging on the web and consultation with those who knew him allow me to sketch out the bare outlines of his academic life. Unlike the lives of our itinerant contemporary scholars, who do their undergraduate studies at one institution, their PhD degrees at another, get their starter jobs at a third, and often move several more times before retiring, Kling received his BA, MA and PhD from Washington University and joined the Political Science Department faculty in 1946, three years before completing his PhD in 1949. He wrote a dissertation that is perhaps best classified as diplomatic history, a subject much in vogue at the time (Kling 1949). Kling spent the rest of his career at Washington University, rising through the ranks and, at a relatively young age, moved into university administration, serving as dean of arts and sciences and also as provost. Despite the strong reception to the article under discussion here (as evidenced by the high citation rates of the piece), Kling did not prove to be a prolific scholar. While today's electronic search engines may have missed some of his writings, as far as I can tell, this piece and few others were his only published studies.1 When Kling retired as provost from Washington University in 1983, a chair was established in his honor. Curiously enough, it was not in political science but was designated the Merle Kling Professor of Modern letters and has been held ever since by scholars in the humanities. The first two paragraphs of the Kling article, 'Towards a Theory of Power and Political Instability in Latin make it clear that it was going to be different from the standard political science papers of the day. Despite its title, focused on power and stability Latin America, Kling does not mention these topics at all in his introduction. Rather, he begins by making a forceful statement about the philosophy and practice of the social sciences. The terminology he uses will, no doubt, confuse the young social scientist of today. Kling begins by criticizing empiricism, yet the rest of the article self-consciously provides a great deal of data. Kling uses the term empiricism, however, in the manner in which physicians do when they refer with derision to empirical medicine, that is, treating the symptoms presented by a patient without any attempt to diagnose the underlying illness. Kling's critique is to make a strong case against what he calls speculations unrelated to experience (p. 21) and demands that political scientists start to build explicit theories based on real-life data. Kling directly targeted the field of political theory. He says: Academically, in fact, the field of political theory, within the discipline of political science, traditionally has defined its role as recording, with varied degrees of interpretation, the history of metaphysical speculations in the area of politics and the state (p. 21). To support his argument he cites approvingly what was later to become a long-standing classic, written by the then Young Turk David Easton in his 1953 book, The Political System: An Inquiry into the State of Political Science. With one bold stroke, Kling on the one hand condemns the subfield of political theory as being hopelessly removed from observation, while on the other he seeks to legitimize the enterprise of theory building based on evidence. …