A social system is the patterned series of interrelationships existing between individuals, groups, and institutions and forming a whole.
Talcott Parsons was the first to formulate a systematic theory of social systems, which he did as a part of his AGIL paradigm. He defined a social system as only a segment (or a "subsystem") of what he called action theory.
Jay Wright Forrester described three counter-intuitive behaviours as important: causes from symptoms are often far removed in time and space, identifying leverage points and conflicting short and long-term consequences.
Niklas Luhmann believes in the significance of communicative processes...