The system becomes logically closed when each of the logical implications which can be derived from any one proposition within the system finds its statement in another proposition in the same system.

Houdton: Cap and Gown Press 1987. Sutton The Radical Marxist. D.

Parsons analyzed the work of Émile Durkheim and Vilfredo Pareto and evaluated their contributions through the paradigm of voluntaristic action. For Parsons "structural functionalism" was a particular stage in the methodological development of the social science and "functionalism" was a universal method; neither term was a name for any specific school. Parsons was also largely responsible for introducing and interpreting Max Weber's work to American audiences.