From "The Deflationist", Larissa MacFarquhar on Paul Krugman, The New Yorker, 1.3. 2010
Again, as in his trade theory, it was not so much his idea that was significant as the translation of the idea into mathematical language. “I explained this basic idea”—of economic geography—“to a non-economist friend,” Krugman wrote, “who replied in some dismay, ‘Isn’t that pretty obvious?’ And of course it is.” Yet, because it had not been well modelled, the idea had been disregarded by economists for years. Krugman began to realize that in the previous few decades economic knowledge that had not been translated into models had been effectively lost, because economists didn’t know what to do with it. His friend Craig Murphy, a political scientist at Wellesley, had a collection of antique maps of Africa, and he told Krugman that a similar thing had happened in cartography. Sixteenth-century maps of Africa were misleading in all kinds of ways, but they contained quite a bit of information about the continent’s interior—the River Niger, Timbuktu. Two centuries later, mapmaking had become much more accurate, but the interior of Africa had become a blank. As standards for what counted as a mappable fact rose, knowledge that didn’t meet those standards—secondhand travellers’ reports, guesses hazarded without compasses or sextants—was discarded and lost. Eventually, the higher standards paid off—by the nineteenth century the maps were filled in again—but for a while the sharpening of technique caused loss as well as gain.
Translating unmappable facts into economic discourse, it turned out, was what Krugman was better at than anyone else: he could take an intriguing notion that had come up in real-world discussions, pare away the details (knowing just what to take out and what was essential), and refine what was left into a clean, clever, “cute” (as he liked to put it), and simple model. “It’s poetry,” Kenneth Rogoff, an economist at Harvard, says. “I mean, you go back to his first book and there was this beautiful chart about what the Volcker contraction did to output that swept aside so much—he just drew this little graph which really cleared the air. I’ve heard economists use the word ‘poet’ in describing him for decades.”
Krugman’s theories of trade and economic geography are still taught everywhere. “I think there’s a pretty good case to be made that the stuff that I stressed in the models is a less important story than the things that I left out because I couldn’t model them, like spillovers of information and social networks,” he says. But failure to represent reality accurately is rarely a fatal flaw in an economics model—what’s valued is the model’s usefulness as an analytic tool. The most successful paper Krugman ever wrote was about target zones, and it was completely wrong. In the years before Europe adopted the euro, it was thought that establishing something between floating exchange rates and fixed ones—a “target zone” within which a currency would be allowed to float—might reap some of the advantages of each. He estimates that by the time the paper was officially published, in 1991, some hundred and fifty derivative papers had already appeared. “Empirically, it doesn’t work at all,” Krugman says. “People loved it as an academic thing, but it had some very strong predictions about interest rates inside target zones. Those predictions all turned out to be wrong. But nobody attacked me for that. I was showing that if target zones worked the way that people say they’re supposed to work, then this is how it would play out.”
