Comte pioneered the study of social "statics" (order) and "dynamics" (progress) from his investigations into the basis of social stability (Wallace & Wolf, 1995, p. 19). He stated functionalism's basic assumption of interdependence when he said the study of social systems required investigation into the action and reaction of the different parts of the social system. He also pioneered the concept of equilibrium when he borrowed biological principles of homeostasis to illustrate that a disharmony between the whole and parts of the social system was pathological (Wallace & Wolf, 1995, p. 19). However, Comte also believed that man progresses through three states of thought and society: theological, metaphysical, and the dawning "positivist" model (Wallace & Wolf, 1995, p. 47). Thus, his theory relies on an investigation into the order of society that maintains equilibrium (statics) as the society experiences the changes that lead to its evolution (progress).
Parsons and Luhmann are both heirs to Comte's practice of studying the structures that maintain equilibrium in a society as the society undergoes the necessary changes that lead to its evolution. Parsons describes a dynamic equilibrium that produces harmony for the system (Wallace & Wolf, 1995, p. 39). He argues that mechanisms of socialization and social control maintain equilibrium by fulfilling "needs" and solving recurring problems like a biological organism does in its physical environment (Wallace & Wolf, 1995, p. 43). Luhmann's definition of equilibrium is tied to his concept of a self-referential society, meaning the system can observe and reflect on itself and make decisions as a result (Wallace & Wolf, 1995, p. 70). Thus, self-referential systems can define themselves and maintain equilibrium through self-conscious mechanisms. He gives an example when he says that the scientific subsystem "reflects on itself in fundamental theorizing and in its decisions to c...