This paper claims that some elements of the complexity approach, which has been recently applied to economics, were already contained in Keynes' economics, and argues for the fecundity of an interaction between them. One of the central ideas of the complexity approach is that individual actions have unintended overall consequences as a result of a self-organization process, which allows the functioning of the system. Keynes played around with the idea of unintended consequences of individual actions, for instance, in the formulation of the paradox of parsimony, in the analysis of the expectations formation, and in the inclusion of the multiplier effect. It is argued that the complexity of the economy, from Keynes' perspective, is firstly related to the complexity of the human being. Also, it is suggested that Keynes' view of the economy as a complex organism was influenced by the philosopher G. E. Moore.
Keynes; John Maynard; Complexity; Self-organization