Luhmann N. (1994) Observing re-entries. ProtoSociology 6: 4–15. https://cepa.info/6718
ProtoSociology 6: 4–15.
Fulltext at https://cepa.info/6718
Rationality can be defined as a re-entry of a distinction in itself and in particular as a re-entry of the distincition between system and enviroment in the system. This is a paradoxical and, for practical matters, utopian concept. It has the advantage that one can show that different “unfoldments” of the paradox are possible and that choosing one of them depends upon historical conditions of plausibility.