From the point of view of an observer, the world is the unity of the difference between system and environment. The world is the unity of every distinction made by an observer; it can never be observed as a unity, thus the world is the blind spot for every observer.
In Old-European cosmology, the world was conceived as an aggregate consisting of the entirety of all visible and invisible things (*universitas rerum or aggregatio corporum*). In the functional differentiated society [→Differentiation of Society], this term loses its references to “things” and instead refers to the indeterminacy of meaning [→Meaning Dimension].
3 meaning dimensions
The temporal dimension represents an open and therefore uncertain future that makes every plan and prognosis contingent. The fact dimension is conceived as an unending (and therefore indeterminable) network of possible causal relations that does not determine in advance which relations should be taken into account. In the social dimension, individuals are conceived as equal subjects, so that social order can no longer be based on each individual nature—on the contrary, actions are generated by the indeterminacy of each individual.
Against this background, the world can be grasped as the ultimate horizon that transcends all three meaning dimensions, as well as a formless correlate of the operations that take place within it. The world is the unity of past and future, of observer and observed, of ego and alter ego.
If we increase the degree of abstraction of the perspective taken here and refer to George Spencer Brown’s calculus, we can grasp the world as an unmarked space divided into two parts by a distinction, which introduces the possibility to distinguish an internal and an external side [→Operation/Observation]. In other words, observers can only operate in a world in which they make distinctions. The chosen distinction indicated as form allows something to be made visible, but, in the same moment, the operation causes what cannot be indicated by the distinction to be hidden—namely, the distinction itself.
However, the world must remain distinguishable by its observations and descriptions, because the observations and descriptions themselves are only possible through the operations that take place in the world. Only in this way is it possible to see which distinctions can be used for observation and distinction and what their consequences are.
In this sense, the world is a paradoxical concept [→Paradox], since it conceives of itself always as a combination of determinacy and indeterminacy, of unity and difference. The world cannot be distinguished from the outside, but its unity can only be conceived as difference, for instance as the difference between the self and outside the self, or between a system and its environment: we cannot indicate without distinguishing.
The paradox emerges in the idea of a world that includes itself [→Re-entry]. How can we distinguish something that is the unity of every distinction? How can observers indicate the unity of the distinction between themselves and their environments?
We encounter the same paradoxical situation when we start out from the idea that a distinction attempts to indicate its unity—i.e., both of its sides—through only one of the two sides. This is the case, for instance, for the codes of →symbolically generalized media, which, when applied to themselves, must simultaneously use a difference (that of the code) and indicate its own unity. [G.C.] – (Unlocking Luhmann, p 253– 254)
Social Systems (1995: Ch. 5.VIII); Weltkunst (1990); Theory of Society (2012: Ch. 1.10).