Complexity, and the capacity for dealing with it, however, is not just the hidden motive, the unifying purpose behind the whole conceptual orientation of the functional method; it is at the same time the most fundamental substantive problem for functional research. It is only from the standpoint of its uttermost complexity that it is worthwhile attacking the problem of the world as a whole, the universal horizon of all human experience. Since it has no boundaries, the world is not a system. There being nothing external to it, it cannot be threatened. Even radical changes in its form of energy can be interpreted only as events within the world. The world poses a problem only in relation to the existence of true and consistent identities, due to its spatial and temporal complexity and due to its superabundance of realities and possibilities, which make it virtually impossible for stable expectations to emerge. This inhibits successful adaptation to the world by the individual. From its interior the world appears as unmanageable complexity, and this is the aspect of the problem that it presents for systems which seek to maintain themselves in the world.

Niklas Luhmann, Trust and Power, loc. 98