Complexity and Economic Policy

Alan Kirman:

Complexity and Economic Policy, OECD Insights: ...Economic theory has... developed increasingly sophisticated models to justify the contention that individuals left to their own devices will self organise into a socially desirable state.  However, in so doing, it has led us to a view of the economic system that is at odds with what has been happening in many other disciplines.

Although in fields such as statistical physics, ecology and social psychology it is now widely accepted that systems of interacting individuals will not have the sort of behaviour that corresponds to that of one average or typical  particle or individual, this has not had much effect on economics. Whilst those disciplines moved on to study the emergence of non-linear dynamics as a result of the complex interaction between individuals, economists relentlessly insisted on basing their analysis on that of rational optimising individuals behaving as if they were acting in isolation. ...

Yet this paradigm is neither validated by empirical evidence nor does it have sound theoretical foundations. It has become an assumption. ...

As soon as one considers the economy as a complex adaptive system in which the aggregate behaviour emerges from the interaction between its components, no simple relation between the individual participant and the aggregate can be established. Because of all the interactions and the complicated feedbacks between the actions of the individuals and the behaviour of the system there will inevitably be “unforeseen consequences” of the actions taken by individuals, firms and governments. Not only the individuals themselves but the network that links them changes over time. The evolution of such systems is intrinsically difficult to predict, and for policymakers this means that assertions such as “this measure will cause that outcome” have to be replaced with “a number of outcomes are possible and our best estimates of the probabilities of those outcomes at the current point are…”. ...

...in trying to stabilise such systems it is an error to focus on one variable either to control the system or to inform us about its evolution. Single variables such as the interest rate do not permit sufficient flexibility for policy actions and single performance measures such as the unemployment rate or GDP convey too little information about the state of the economy.