Memory is not a stored past. The past is past and can never become current again. Memory is rather a kind of consistency check, whereby it is typically not necessary to remember when one has learned or not learned something specific. If I speak German now, I don't need to know when I learned this language and how it came about in the first place, or when I first used certain words like " autopoiesis" or read them for the first time. What is decisive for what one wants to achieve in the future in the context of expectations, of anticipations, of objectives and the like, is the current retrievability, the current testing of the breadth of use, if you will, of structures. In that sense, this is quite a pragmatist approach. There is a connection between memory theory on the one hand and a pragmatic future orientation on the other, which is always conducted nice and tight, so that one could perhaps also say that memory is nothing other than an ongoing consistency check of different information with regard to certain expectations, be it that one wants to achieve something, be it that one fears something, be it that one sees something coming and wants to react to it. We are not dealing with a theory of memory that provides for any kind of memory. […]
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Luhmann, Einführung in die Systemtheorie, p. 102.