ICYMI, this week serious questions were raised about a controversial and influential paper by Harvard economists Carmen Reinhart and Kenneth Rogoff that purported to show -- or at least has been taken to show -- that when a country's national debt reaches about 90% of GDP, that debt acts as a significant drag on growth. On April 15, Thomas Herndon, Michael Ash and Robert Polin published a paper alleging that Reinhart and Rogoff's paper contained, along with various methodological errors, a coding error in an Excel spread sheet. In response, Reinhart and Rogoff acknowledge the error, but defend their methodology and maintain that the error does not materially affect their conclusions. They also claim that they never stated categorically that higher debt caused lower growth. It's that question of how a politically freighted point is communicated and received that interests me here.
On his blog, Paul Krugman cried "casuistry" on that last point:
And the everyone hyping Reinhart-Rogoff very much included Reinhart and Rogoff themselves. Matt O’Brien has the goods. It’s true that their papers never said outright that the relationship was causal, but they weren’t anywhere near that scrupulous in op-eds and other media presentations. And the truth is that the papers may not have stated causation flatly, but it was clearly insinuated. By trying to claim now that they never meant to imply such a thing, R-R are falling down seriously in the menschhood test.
Today, Krugman, austerity's most stalwart enemy, devoted a whole column to the kerfuffle. And while I'm happy to see him hammer away at the foundations of the case for austerity, I must say that he replicates the alleged rhetorical error. That is, he gets cutesy with causality. The whole essay is set up to convey a conclusion that he somewhat airily dismisses in the final sentence.
The opening paragraph poses a pretty grandiose premise:
