Keynes' and the Santa Fe Institute's Complexity: Same Concepts, Different Methods?

Keynes’ ‘fallacy of composition’ and, later, the ‘Santa Fe perspective’ have shown that the economy may be defined as a “complex adaptive system”, since it is not something given but results from constantly developing interactions among heterogeneous individuals. Endorsing the definition of ‘dynamic complexity’, the paper analyses the extent to which Keynes’ notion of complexity is coterminous with the one developed at the Santa Fe Institute. An analysis of the role of expectations in the General Theory, along with the dimension of time, history and path-dependence, makes it possible to conceive Keynes’ work as an open, complex evolving system and to establish a direct connection with the ‘Santa Fe perspective’. However, Keynes’ “two-stage methodology” which allows the analyst to deal with complex organic material without resorting to reductionism by means of ordinary language involves the inherent non-measurability of complex magnitudes which does not depend on the individual’s limited ability to measure the complex object. This feature may cast some doubts on the inheritance of Keynes’s methodology by the ‘Santa Fe perspective’, which attempts to handle complexity through simulation techniques implicitly based on a sophisticated mathematical formalism.