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World / Luhmann: from the perspective of an observer the world is the unity of the difference between system and environment - as a unit it can never be observed. It is the blind spot of each observer -
Def World / Luhmann / Reese-Schäfer: the last horizon all meaning. World is related to sense as environment is related to system - an open term for all that is opposed to the mind - but not the universe - no wholeness.
Einführung in die Systemtheorie Heidelberg 1992
Die Kunst der Gesellschaft Frankfurt 1997