There are abbreviated definitions of the subject matters of sociology, political science, of economics -- "Sociology is the study of groups and norms," "political science is the study of the institutions and behavior through which political decisions are made," "economics is the study of rational behavior in the context of scarcity". And likewise for the core methods of inquiry and explanation. But the questions remain: Is this a logical way of covering the domain of possible inquiry?Are there areas of phenomena that are overlooked in this taxonomy? And pragmatically--is this combination of topics, scopes, and methods likely to solve the problems of explanation and policy to which we would like the social sciences to contribute?
It is worth noticing in this discussion that each of the core disciplines of the social sciences is actually an umbrella encompassing a wide range of sub-disciplines, and these sub-disciplines themselves show significant variation in assumptions about subject matter, ontology, and methodology. Within political science, for example, there are wide rifts between new institutionalists, rational choice theorists, comparativists, area specialists, and American politics specialists, and there is no common perspective that gives substantial coherence across these divides. Similar observations are true of economics, anthropology, and sociology as well.
So how should we begin to analyze the status and adequacy of the current definitions of the social science disciplines?
What would we want from a division of the disciplines in a large field of study (biology, physics, social science, psychology)? This is an epistemic question: we want to know how best to go about acquiring knowledge about a broad domain of phenomena. We would want to be sure that the most fundamental processes and the most practically important phenomena are given close scrutiny. We would want to be sure that there are a variety of methods of inquiry that are well designed and effective in probing the nature of the phenomena under study. And, of course, we would want the disciplines to be organized in such a way that practitioners are motivated and evaluated towards valid discovery. Finally, it would appear logical that we would want there to be mechanisms of scientific communication through which discoveries and insights in one discipline may inform or deepen the discoveries of other neighboring disciplines.
This last point deserves emphasis. Disciplines provide focus; they encourage researchers to dig deeply into the specialized problems and methods that have been defined by the discipline. But it is also true that specialization creates tunnel vision -- with the result that scientific understanding of a complex phenomenon may miss essential parts of the process because they overlap disciplinary definitions of subject matter. So a logical expectation of the organization of scientific knowledge would presumably include a process through which interdisciplinary sharing is encouraged and facilitated.
It needs also to be noted that it is entirely possible for a discipline to be mis-conceived. The founders may have taken a wrong turn in highlighting what appeared to be the most important phenomena and mechanisms; the discipline may have adopted methodological commitments that were fashionable at a time but poorly fitted to the research problems of the subject matter (extreme behaviorism in psychology, for example); the disciplinary institutions (journals, universities) may have designed procedures of peer review that were discouraging to genuine progress in the discipline's ability to gain knowledge about the subject matter.
There are many threads that this subject opens. But a few preliminary observations are justified. First, it is worth observing that the social world does not come to us with a prior division of phenomena into "economic," "ethnographic," or "sociological." So the social world itself does not dictate the way in which we parcel out research problems across specialists. Almost all social phenomena have dimensions of each of these characteristics, and the methods of each of these disciplines are relevant to inquiry and explanation of a single phenomenon. So the insistence on using only the methods of one's discipline in analyzing a complex social phenomenon is a problem--along the lines of the saying that "to a person with a hammer, everything looks like a nail". Second, it is noteworthy that each of the major social science disciplines has undergone harsh "methodology wars" in the past several decades--between rational choice theory and more empirical research in political science, between quantitative and qualitative researchers in sociology, or between interpretive and materialist ethnography methods. Are these disputes productive of further discovery into the workings of the social world? It is not evident that they are. And third, the points made above about the general utility of interdisciplinary communication and collaboration seem especially applicable to the social sciences. Given the inherently complex and mixed nature of social phenomena, surely the social sciences would benefit from a greater degree of interdisciplinarity and mutual respect. Pluralism in theory and method would seem to best serve the goals of the social sciences.
(See Andrew Abbott, Chaos of Disciplines, for a lively and illuminating examination of the social science disciplines.)