'Mathiness in the Theory of Economic Growth'

Paul Romer:

My Paper “Mathiness in the Theory of Economic Growth”: 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. It should eventually be available on the AER website but has not been posted yet. 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. As scientists, we have to hold ourselves to a standard that requires us to reach a consensus about which model is right, and then to move on to other questions.

The alternative to science is academic politics, where persistent disagreement is encouraged as a way to create distinctive sub-group identities.

The usual way to protect a scientific discussion from the factionalism of academic politics is to exclude people who opt out of the norms of science. The challenge lies in knowing how to identify them.

From my paper:

The style that I am calling mathiness lets academic politics masquerade as science. Like mathematical theory, mathiness uses a mixture of words and symbols, but instead of making tight links, it leaves ample room for slippage between statements in natural versus formal language and between statements with theoretical as opposed to empirical content.

Persistent disagreement is a sign that some of the participants in a discussion are not committed to the norms of science. Mathiness is a symptom of this deeper problem, but one that is particularly damaging because it can generate a broad backlash against the genuine mathematical theory that it mimics. If the participants in a discussion are committed to science, mathematical theory can encourage a unique clarity and precision in both reasoning and communication. It would be a serious setback for our discipline if economists lose their commitment to careful mathematical reasoning.

I focus on mathiness in growth models because growth is the field I know best, one that gave me a chance to observe closely the behavior I describe. ...

The goal in starting this discussion is to ensure that economics is a science that makes progress toward truth. ... Science is the most important human accomplishment. An investment in science can offer a higher social rate of return than any other a person can make. It would be tragic if economists did not stay current on the periodic maintenance needed to protect our shared norms of science from infection by the norms of politics.

[I cut quite a bit -- see the full post for more.]