When a field of study begins to develop more rigorous methods, well-defined concepts, and greater emphasis on systematic comparison, it is well on the way to becoming a science. In the past decade or so, these traits have become increasingly evident in the study of comparative politics and international politics. But the development of sharper methodology and conceptual sophistication on the part of individual researchers is not quite sufficient. One of the earmarks of a healthy scientific discipline is the extent to which each set of findings may be compared to and combined with the results of earlier investigations; in short, research must become cumulative. Certain obstacles still inhibit us, among which might be counted: disagreement as to the precise boundaries of comparative and international politics; highly disparate theoretical frameworks; lack of consensus regarding the specification and measurement of key variables; and insufficient data storage and retrieval arrangements. Another difficulty has been in the absence of a generally agreed delineation of our empirical domains: What are the political entities whose attributes and relationships must concern us? More simply, we have not yet defined our population, and until the population is defined, we know neither the domain about which we seek to generalize, nor the criteria for selecting a sample from that population.

Although this is hardly the most pressing issue facing our two fields, and while a successful delineation of our population is far from a sufficient condition for the growth of a scientific discipline, it does strike us as a necessary precondition.