"Luhmann’s take on systems theory was not conventional. It could be better likened to systems theory 2.0."
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"Systems theory 1.0 revolves around the mereological notion of whole-part theory. In this model, the system equals the whole. The parts are like organs in a body yet are thought of as more modular and static in nature. When you think of systems theory 1.0, think simple input-output machines (like a vending machine). You put a dollar in, and it spits out a snack (assuming it doesn’t get stuck)!"
See also Marc Pierson's page:
A collection of stateful parts in meaningful (recognizable) relationship (processes) with one another, that taken together has characteristics that none of the parts have alone or in lesser combinations.
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A *system* is defined by the connected components of the page reference graph. Distinct systems are fully independent. tweet 
by Konrad Hinsen