Who Needs Microfoundations?

Posted on



I’m currently reading Justin Fox’s new book, The Myth of the Rational Market, which is recommended. Specifically, immediately before leaving for work I read a brief aside he wrote about the formation of a Kuhnian “paradigm” in economics in the second half of the twentieth century and economists’ pride in having achieved that kind of methodological consensus and thus elevated themselves above the ranks of mere sociologists or some such. That’s what sprung to mind as I read this paragraph from Steven Levitt:

You might think that macro forecasting would be an important part of what academic economists would do, but in practice there is almost nothing of that sort being done. That sort of thing is left for economists at places like the Federal Reserve or private banks to do. You might think that the models that most successfully explain economic patterns would rise to the top, but in the current regime, if they are not meticulously constructed from “micro foundations,” they aren’t allowed to be considered.

From an outside perspective, what seems to be going on is that economists have unearthed an extremely fruitful paradigm for investigation of micro issues. This has been good for them, and enhanced the prestige of the discipline. No such fruitful paradigm has actually emerged for investigation of macro issues. So the decision has been made to somewhat arbitrarily impose the view that macro models must be grounded in micro foundations. Thus, the productive progressive research program of microeconomics can “infect” the more troubled field of macro with its prestige.

Which, as a sociological matter, I think you’d have to say has worked.

But as a methodological matter, it seems deeply unsound. As a general principle for investigating the world, we normally deem it desirable, but not at all necessary, that researchers exploring a particular field of inquiry find ways to “reduce” what they’re doing to a lower level. To make that concrete, in the modern day we have achieved a decent understanding of how principles of chemistry are grounded in physics’ understanding of the behavior of atoms. But it’s just not the case that advances in chemistry were made by demanding that chemists ground all their models in subatomic physics. On the contrary, chemistry moved forward in the first instance by having chemists investigate issues in chemistry and see which models and theories held up. Similarly, though psychology is intertwined with the detailed study of the biology of the brain, it’s not deemed illegitimate to research psychological issues in the absence of a specific neurological theory. Nor, for that matter, do microeconomists generally deem it necessary to explore in detail the psychological foundations of their models. The models are, rather, judged by whether or not they produce fruitful insights about economics. Trying to enhance models with better information about psychology isn’t against the rules, but it’s not required either. What’s required is that the models do useful work.

So why should it be that “in the current regime, if [macro models] are not meticulously constructed from “micro foundations,” they aren’t allowed to be considered”?