You might think that my undergraduate degree is the kind of thing I’d remember. But if so, you’d be wrong. A colleague noticed that in my post about protecting the norms of science, I wrote that I had an undergraduate degree in physics, but my CV says (correctly) that my undergraduate degree from the University of Chicago is a B.S. in Math. I was a physics major for most of my time there, and physics was the focus of my coursework.

In a recent post, Simon Wren-Lewis suggests: i) that there is something wrong in economics, and ii) that the problem lies at a level that is deeper than individual models that are wrong. I agree with both assertions. To make point (ii), he writes, “the discussion needs to be about methodology, rather than individual models.” I suggest that we frame this look at the deeper level in a slightly different way–in terms of the norms of science, not in terms of methodology.

In his comment on my Mathiness paper, Noah Smith asks for more evidence that the theory in the McGrattan-Prescott paper that I cite is any worse than the theory I compare it to by Robert Solow and Gary Becker. I agree with Brad DeLong’s defense of the Solow model. I’ll elaborate, by using the familiar analogy that theory is to the world as a map is to terrain. There is no such thing as the perfect map.

In my Mathiness article, I refer to this quote from Lucas (2009): Some knowledge can be ‘embodied’ in books, blueprints, machines and other kinds of physical capital, and we know how to introduce capital into a growth model, but we also know that doing so does not by itself provide an engine of sustained growth. Ask yourself these three questions: 1. Which logical quantifier on the set of models does Lucas need to insert before “doing so does not …” to make the clause that follows the conjunction “but” true?

I have a new paper in the Papers and Proceedings Volume of the AER that is out in print and on the AER website. A short version of the supporting appendix is available here and on the AER website. A longer version with more details behind the calculations is available here. The point of the paper is that if we want economics to be a science, we have to recognize that it is not ok for macroeconomists to hole up in separate camps, one that supports its version of the geocentric model of the solar system and another that supports the heliocentric model.