Social Theory and Systems Theory : Luhmann

Luhmann's systems theory focuses on three topics, which are interconnected in his entire work.^[6]

1. Systems theory as societal theory
2. Communication theory and
3. Evolution theory

The core element of Luhmann's theory is communication. Social systems are systems of communication, and society is the most encompassing social system. Being the social system that comprises all (and only) communication, today's society is a world society. A system is defined by a boundary between itself and its environment, dividing it from an infinitely complex, or (colloquially) chaotic, exterior. The interior of the system is thus a zone of reduced complexity: Communication within a system operates by selecting only a limited amount of all information available outside. This process is also called "reduction of complexity." The criterion according to which information is selected and processed is meaning (in German, Sinn). Both social systems and psychical or personal systems (see below for an explanation of this distinction) operate by processing meaning.

Furthermore, each system has a distinctive identity that is constantly reproduced in its communication and depends on what is considered meaningful and what is not. If a system fails to maintain that identity, it ceases to exist as a system and dissolves back into the environment it emerged from. Luhmann called this process of reproduction from elements previously filtered from an over-complex environment autopoiesis (pronounced "auto-poy-E-sis"; literally: self-creation)  (Closed constituative?), using a term coined in cognitive biology by Chilean thinkersHumberto Maturana and Francisco Varela. Social systems are autopoietically closed in that while they use and rely on resources from their environment, those resources do not become part of the systems' operation. Both thought and digestion are important preconditions for communication, but neither appears in communication as such.

Luhmann likens the operation of autopoiesis (the filtering and processing of information from the environment) to a program, making a series of logical distinctions (in German,Unterscheidungen). Here, Luhmann refers to the British mathematician G. Spencer-Brown's logic of distinctions that Maturana and Varela had earlier identified as a model for the functioning of any cognitive process. The supreme criterion guiding the "self-creation" of any given system is a defining binary code. This binary code, is not to be confused with the computers operation: Luhmann (following Spencer-Brown and Gregory Bateson) assumes that auto-referential systems are continuously confronted with the dilemma of disintegration/continuation. This dilemma is framed with an ever-changing set of available choices; everyone of those potential choices can be the system's selection or not (a binary state, selected/rejected). The influence of Spencer-Brown's book, Laws of Form, on Luhmann can hardly be overestimated.

Although Luhmann first developed his understanding of social systems theory under Parsons' influence, he soon moved away from the Parsonian concept. The most important difference is that Parsons used systems merely as an analytic tool to understand certain processes going on in society; Luhmann, in contrast, treats his vision of systems ontologically, saying that "systems exist". That is, Luhmann in fact suggests to substitute the paradigm of systems theory for the ontological paradigm: the difference system/environment (which also signifies a relationship).

Luhmann himself described his theory as "labyrinth-like"or "non-linear" and claimed he was deliberately keeping his prose enigmatic to prevent it from being understood "too quickly", which would only produce simplistic misunderstandings.^{[4] (nothing new there)}

It seems clear there is lack of understanding between the systems and post-structural schools of thought

The relation between the term  "System" and "Text" : c.f the "Text" creating subject positions (Discourse Analysis)