Lucas Interview

Stephen Williamson notes an interview of Robert Lucas:

SED Newsletter: Lucas Interview: The November 2012 SED Newsletter has ... an interview with Robert Lucas, which is a gem. Some excerpts:

... Microfoundations:

ED: If the economy is currently in an unusual state, do micro-foundations still have a role to play?

RL: "Micro-foundations"? We know we can write down internally consistent equilibrium models where people have risk aversion parameters of 200 or where a 20% decrease in the monetary base results in a 20% decline in all prices and has no other effects. The "foundations" of these models don't guarantee empirical success or policy usefulness.

What is important---and this is straight out of Kydland and Prescott---is that if a model is formulated so that its parameters are economically-interpretable they will have implications for many different data sets. An aggregate theory of consumption and income movements over time should be consistent with cross-section and panel evidence (Friedman and Modigliani). An estimate of risk aversion should fit the wide variety of situations involving uncertainty that we can observe (Mehra and Prescott). Estimates of labor supply should be consistent aggregate employment movements over time as well as cross-section, panel, and lifecycle evidence (Rogerson). This kind of cross-validation (or invalidation!) is only possible with models that have clear underlying economics: micro-foundations, if you like.

This is bread-and-butter stuff in the hard sciences. You try to estimate a given parameter in as many ways as you can, consistent with the same theory. If you can reduce a 3 orders of magnitude discrepancy to 1 order of magnitude you are making progress. Real science is hard work and you take what you can get.

"Unusual state"? Is that what we call it when our favorite models don't deliver what we had hoped? I would call that our usual state.