Complexity, from a systems theoretical perspective, equates to a system’s horizon of possibilities. A horizon may be approached but never crossed, as it keeps receding. A choice with many equally good or equally bad possibilities is a complex choice. The key point is that systems reduce complexity in order to solve problems. Or as Luhmann ) puts it,
“[Evolutionary] advances reduce complexity in order to organize greater complexity on the basis of restriction. Thus a road network reduces the possibilities for movement to enable easier and faster movement and hence increase options for movement concretely available.”Theory of Society, 2012, p. 306
Many cities are built on grid design for this reason. The grid reduces the possibilities for automobile and pedestrian movement while enhancing the efficiency of movement. Within the limitations of the grid, options for movement actually increase because one-way and two-way streets can be built; sidewalks, by custom, may be split into left and right for movement in opposite directions; city blocks may be more or less the same length, which enhances predictability and creates a sense of rhythm.
There is more to horizons, however, because systems have two horizons, or “twin horizons” (Luhmann ). On one side there are infinite possibilities, while on the other side there are zero possibilities. Henry Ford famously said that consumers can have a car in any color they want as long as it is black. Of course, this is no choice at all, as long as the person still wants a car. Albert Einstein reportedly wore the same kind of suit every day to avoid wasting mental energy making deciding what the wear. (This anecdote may be apocryphal as innumerable quotes have been attributed to Einstein.) While in office, Barack Obama said that he only wore grey or blue suits for the same reason.