You must remember what Keynesians forgot
Guest Post by WorldComplex.
One characteristic of time series that we have been able to study through reconstructed phase spaces is the concept of long memory. In principle, the future evolution of the state of a complex system is dependent on the entire past history of the system.
The prescriptions of Keynesianism in modern economics ignores the long memory of the system. Keynesians believe that application of policy A brings about response B. In a system with long memory, the response is also dependent on the previous history of the system–hence lowering interest rates in 2011 does not bring about the same response as lowering them in 2001–because the history prior to 2011 differs from history prior to 2001.