The central concept around which the theory of social systems as developed by the later Niklas Luhmann is built is the concept of autopoiesis, originally developed by the two Chilean biologists Humberto Maturana and Francisco Varela. Autopoiesis (< Greek: autos = self, poiein = to produce) means self-(re)production. Autopoietic systems thus are systems that reproduce themselves from within themselves, as for example a plant reproduces its own cells with its own cells. Luhmann argued that the basic idea of autopoiesis applied not only to biological but also to a large number of non-biological systems. He thus appropriated the originally biological concept, modified it and applied it to the social domain. In a similar way as biological systems social systems were thus conceptualised as systems that reproduced their own elements on the basis of it own elements. In this paper Luhmann’s concept of autopoietic social systems will be introduced starting with the originally biological concept of autopoiesis by Maturana / Varela and Luhmann’s modification of it as a general systems concept (section 1). Based on that Luhmann’s concept of social systems as a specific type of autopoietic system will be explained (section 2). The third and fourth sections will describe and explain the three existing types of social systems: societal system, interaction system and organisational system. In the fifth section the mathematical calculus of distinction by George Spencer Brown will be introduced, which Luhmann has been drawing on extensively in his later writings, and its relevance for Luhmann’s theory will be shown.

Niklas Luhmann’s theory of social systems has been widely influential in the German-speaking countries in the past few decades. However, despite its significance, particularly for organization studies, it is only very recently that Luhmann’s work has attracted attention on the international stage as well. This Special Issue is in response to that. In this introductory paper, we provide a systematic overview of Luhmann’s theory. Reading his work as a theory about distinction generating and processing systems, we especially highlight the following aspects: (i) Organizations are processes that come into being by permanently constructing and reconstructing themselves by means of using distinctions, which mark what is part of their realm and what not. (ii) Such an organizational process belongs to a social sphere sui generis possessing its own logic, which cannot be traced back to human actors or subjects. (iii) Organizations are a specific kind of social process characterized by a specific kind of distinction: decision, which makes up what is specifically organizational about organizations as social phenomena. We conclude by introducing the papers in this Special Issue.

Key words: autopoiesis, decision, distinction, luhmann, organization theory, theory of social systems.