Thursday, September 22, 2016

Paul Romer Has A Follow Up To Last Week's "The Trouble With Macroeconomics" (and some digressive commentary)

In his latest piece Professor Romer sounds a tad crabby.
Here's the link and the digression from Bond Economics:

What (Some) Mathematicians Do With Incorrect Proofs In Journals
Paul Romer has a followup article about "post-Real" economics. I just wanted to launch a digression around his comments about mathematicians and incorrect proofs. Although there might be some useful conclusions for academic economics, the problems faced by the field are more difficult than the issue of incorrect proofs.

Romer writes:
This is just post-real Calvinball used as a shield from criticism. Imagine someone saying to a mathematician who finds an error in a theorem that is false,  “you can’t criticize the proof until you come up with valid proof.” 
(As an aside, I should note that agree that DSGE macro stinks, and I have used the Calvinball metaphor myself.)

My academic experience was in Control Systems Theory, a branch of applied mathematics. I ran into a case where I was an anonymous referee for a submitted paper. The new paper contained Theorem B, and Theorem B cited Theorem A within its proof. Meanwhile, Theorem A was contained in another paper that was published in the #2 journal in the field.

The result looked dubious, and I managed to disprove Theorem A within 10 seconds of picking up the volume that held it. (Luckily, the volume opened close to the page with the alleged "proof.") That was a personal speed record, and it was the most entertaining moment of my academic career.

I was able to write a short response rejecting the paper, explaining that the cited theorem was in fact incorrect; hence there was no need to pursue the new paper without a total re-write. Since it was someone else who made the original error, I was able to be quite gracious to the authors. (Although I doubt that made them any happier.)...