The social sciences consist of a variety of disciplines, subject areas, and methods, and there is no reason to expect that these disciplines will eventually add up to a single unified theory of society. Political science, sociology, history, anthropology, economics, geography, and area studies all provide their own, largely independent, definitions of scope, research agenda, and research methods. And there is no grand plan according to which the disciplinary definitions jointly capture all that is of scientific interest about the social.
History rather than logic explains the particular configuration of social science disciplines that we now face. The major social science disciplines have grown up in the past century and a half by creating stylized answers to these topic areas: the “political” concerns institutions of coercion and governance; the “economic” has to do with production, exchange, and distribution of goods and services; the “anthropological” has to do with the cultures, values, and practices through which individuals and groups conduct their local lives. Area studies are defined according to a different axis; Asian studies or Latin American studies demand that we cut the social differently: not from the point of view of social domains, but from the point of view of geographical complexes of related social, cultural, economic, political, and normative regimes.
At the same time, we as “users” of the results of social inquiry have no inherent interest in the intra- and inter-disciplinary debates that have led to the constitution of the disciplines of the social sciences as they currently exist. The social world does not come to us labeled as “political,” “economic,” or “ethnographic.” We ordinary citizens have questions that cut across these boundaries recklessly: Why does the US state so commonly ignore the needs of poor people? Why are Indonesian rice farmers reluctant to make use of HYV rice strains? Why did the hi-tech bubble occur in the American economy in the 1990s? How do police departments succeed in recruiting good potential officers? When is the practice of charitable giving most likely to thrive or falter? Why did the Chinese Communist revolution occur? Why did it succeed? Note what a mixture of topics, human interactions, and methodologies is invoked by this collection of questions. Some of these queries raise the question of why individuals behaved as they did; some focus on group action, while others single out individual choices; some have to do with the institutions within which individuals live; some suggest turning to ethnography, comparative economics, or political science; and so forth.
The upshot is this: Users of the social sciences have a different way of parsing “the social” than is found in academic social science. We are interested in human agency and behavior — individual and collective. We are interested in the ways social relations and institutions work, and how they affect the behavior and choices of the individuals who operate within them. We are interested in how large agglomerations of human activity work — how they emerge, how they behave over time, and how they go wrong (cities, states, corporations, networks of friends, …), and we are interested in the dynamics of face-to-face social interaction.
This suggests that new thinking about the social sciences needs to start with the idea of acquiring a strong commitment to interdisciplinary study of common social topics.
(Here are several other posts on "social science disciplines" (tag).)