This paper summarizes the attempt by Parsons to develop an extensive and arguably comprehensive foundational basis for sociology. Further developments published in Working Papers in the Theory of Action (with Bales and Shils) and Economy and Society (with Smelser) focused on the relationship between the social and the economic system introducing the ‘four-function paradigm’ or AGIL model.

In these books he introduces his system of ‘pattern variables’. In 1951 the results were published in two books, Towards a General Theory of Action (with Shils) and The Social System. He developed some key concepts to characterise the structure of social interaction and then expanded the scope of his framework to cover all aspects of society including some initial thoughts on how it maintains its stability and how it changes. Having developed his action frame of reference and his voluntaristic theory of action in The Structure of Social Action (described in Part A), Talcott Parsons turned his attention to the social system per se. However, the functional differentiation of society, the formation of functionally separate subsystems, was historically able to realize this social organization only in the European development of society from the early Middle Ages, which grew out of the Greco-Roman (Judeo-Christian) foundations, and during the colonizations and the spread of the European population in many parts of the world - especially in North America and Australia. These differentiations have occurred in the societies of a wide variety of civilizations when they have been able to overcome the complexity of the simple horde order and produce a form of literacy. those based on magical and priestly functions) are realized, and then later in the even more extensive literate societies, the immediate sociality of millions of interactions is subdivided into different levels, and the organizational systems that frame them are supplemented, and most importantly, the frames that make up the overall social system are separated. Whereas in the hordes of a few dozen members that make up the oldest societies, all sociality is still achieved through personal interactions, in the more fragmented tribal organizations, leadership and simpler functional divisions (e.g. In more complex societies - or, in other words, in societies that have reached a higher stage of development - the functional dimension reflects the increasing degree of differentiation of the actions that perform certain functions and the institutions that organize them. Functional organization is one of the dimensions of the structuring of society, shaped by the functional needs of society as a whole and its parts.

Structural functional theory article