Peter Lewin notes that
It is an understanding of the incentivized behavior of human beings that allows us to understand and predict invisible-hand outcomes.
Yet, the complexity problem remains. Can we be certain, as a logical matter, that if certain conditions obtain, certain definite types of outcomes will result from the free market process? It is on this type of thinking that the more sophisticated Keynesians might base their arguments for benevolent and effective intervention in the face of economic crisis.
Both the invisible-hand and the mainstream Keynesian argument implicitly take legibility, predictability and stability to be desirable characteristics of economic outcomes. The Keynesian argument sees the illegibility and uncertainty as justification to put in place a system of control whereas the invisible-hand argument claims that the system is legible and at “equilibrium”. The latter operates in a fantasy land and the former through the very act of stabilisation renders stability all the more elusive.