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Why do high-profile economic tussles turn so quickly to ad hominem attacks?Perhaps the most well-known recent example has been the Nobel laureate PaulKrugman’s campaign against the economists Carmen Reinhart and KennethRogoff, in which he moved quickly from criticism of an error in one of their papers to chargesabout their commitment to academic transparency.
For those who know these twosuperb international macroeconomists, as I do, it is evident that theseallegations should promptly be dismissed. But there is the larger question ofwhy the paranoid style has become so prominent.
Part of the answer isthat economics is an inexact science, with exceptions to almost every patternof behavior that economists take for granted. For example, economists predictthat higher prices for a good will reduce demand for it. But students ofeconomics will no doubt remember an early encounter with “Giffen goods,” whichviolate the usual pattern. When tortillas become more expensive, a poor Mexicanworker may eat more of them, because she now has to cut back on more expensivefood like meat.
Such “violations”occur elsewhere as well. Customers often value a good more when its price goesup. One reason may be its signalingvalue. An expensive handcrafted mechanical watch may tell time no moreaccurately than a cheap quartz model; but, because few people can afford one,buying it signals that the owner is rich. Similarly, investors flock to stocksthat have appreciated, because they have “momentum.”
The point is thateconomic behavior is complex and can vary among individuals, over time, betweengoods, and across cultures. Physicists do not need to know the behavior ofevery molecule to predict how a gas will behave under pressure. Economistscannot be so sanguine. Under some conditions, individual behavioral aberrationscancel one another out, making crowds more predictable than individuals. But,under other conditions, individuals influence one another in such a way thatthe crowd becomes a herd, led by a few.
The difficulties foreconomic policymakers do not stop there. Economic institutions can havedifferent effects, depending on their quality. In the run-up to the 2008financial crisis, macroeconomists tended to assume away the financial sector intheir models of advanced economies. With no significant financial crisis sincethe Great Depression, it was convenient to take for granted that the financialplumbing worked in the background.
Models, thussimplified, suggested policies that seemed to work – that is, until theplumbing backed up. And the plumbing malfunctioned because herd behavior –shaped by policies in ways that we are only now coming to understand –overwhelmed it.
So, why not letevidence, rather than theory, guide policy? Unfortunately, it is hard to getclear-cut evidence of causality. If high national debt is associated with sloweconomic growth, is it because excessive debt impedes growth, or because slowgrowth causes countries to accumulate more debt?
Many an econometrician’scareer has been built on finding a clever way to establish the direction ofcausality. Unfortunately, many of these methods cannot be applied to the mostimportant questions facing economic policymakers. So the evidence does notreally tell us whether a heavily indebted country should pay down its debt orborrow and invest more.
Moreover, what seemlike obvious, commonsense policy solutions all too often have unintendedconsequences, because a policy’s targets are not passive objects, as inphysics, but active agents who react in unpredictable ways. For example, pricecontrols, rather than lowering prices, often cause scarcity and the emergenceof a black market in which controlled commodities cost significantly more.
All of this impliesthat economic policymakers require an enormous dose of humility, openness tovarious alternatives (including the possibility that they might be wrong), anda willingness to experiment. This does not mean that our economic knowledgecannot guide us, only that what works in theory – or worked in the past orelsewhere – should be prescribed with an appropriate degree of self-doubt.
ut, for economistswho actively engage the public, it is hard to influence hearts and minds byqualifying one’s analysis and hedging one’s prescriptions. Better to assertone’s knowledge unequivocally, especially if past academic honors certify one’sclaims of expertise. This is not an entirely bad approach if it results insharper public debate.
The dark side of suchcertitude, however, is the way it influences how these economists engagecontrary opinions. How do you convince your passionate followers if other,equally credentialed, economists take the opposite view? All too often, thepath to easy influence is to impugn the other side’s motives and methods,rather than recognizing and challenging an opposing argument’s points. Insteadof fostering public dialogue and educating the public, the public is often leftin the dark. And it discourages younger, less credentialed economists fromentering the public discourse.
In their monumentalresearch on centuries of public and sovereign debt, the normally very carefulReinhart and Rogoff made an error in one of their working papers. The error isin neither their prize-winning 2009 book nor in a subsequent widely read paperresponding to the academic debate about their work.
Reinhart and Rogoff’sresearch broadly shows that GDP growth is slower at high levels of public debt.While there is a legitimate debate about whether this implies that high debt causes slow growth,Krugman turned to questioning their motives. He accused Reinhart and Rogoff ofdeliberately keeping their data out of the public domain. Reinhart and Rogoff,shocked by this charge – tantamount to an accusation of academic dishonesty –released a careful rebuttal, including online evidence that they had not beenreticent about sharing their data.
In fairness, givenKrugman’s strong and public positions, he has been subject to immense personalcriticism by many on the right. Perhaps the paranoid style in public debate,focusing on motives rather than substance, is a useful defensive tactic againstrabid critics. Unfortunately, it spills over into countering more reasoneddifferences of opinion as well. Perhaps respectful debate in economics ispossible only in academia. The public discourse is poorer for this.
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