Lucas Roundtable: Ask the Right Questions
In The Economist, Robert Lucas responds to recent criticism of macroeconomics ("In Defense of the Dismal Science"). Here's my entry at Free Exchange's Robert Lucas Roundtable in response to his essay:
Lucas roundtable: Ask the right questions, by Mark Thoma: In his essay, Robert Lucas defends macroeconomics against the charge that it is "valueless, even harmful", and that the tools economists use are "spectacularly useless".
I agree that the analytical tools economists use are not the problem. We cannot fully understand how the economy works without employing models of some sort, and we cannot build coherent models without using analytic tools such as mathematics. Some of these tools are very complex, but there is nothing wrong with sophistication so long as sophistication itself does not become the main goal, and sophistication is not used as a barrier to entry into the theorist's club rather than an analytical device to understand the world.
But all the tools in the world are useless if we lack the imagination needed to build the right models. Models are built to answer specific questions. When a theorist builds a model, it is an attempt to highlight the features of the world the theorist believes are the most important for the question at hand. For example, a map is a model of the real world, and sometimes I want a road map to help me find my way to my destination, but other times I might need a map showing crop production, or a map showing underground pipes and electrical lines. It all depends on the question I want to answer. If we try to make one map that answers every possible question we could ever ask of maps, it would be so cluttered with detail it would be useless, so we necessarily abstract from real world detail in order to highlight the essential elements needed to answer the question we have posed. The same is true for macroeconomic models.
But we have to ask the right questions before we can build the right models.
The problem wasn't the tools that macroeconomists use, it was the questions that we asked. The major debates in macroeconomics had nothing to do with the possibility of bubbles causing a financial system meltdown. That's not to say that there weren't models here and there that touched upon these questions, but the main focus of macroeconomic research was elsewhere.
One major debate, for example, was the rate at which the macroeconomy returns to its long run equilibrium after a shock. Both New Keynesians and Chicago type equilibrium theorists believed the economy was always moving in the right direction—toward long-run equilibrium—the question was simply how fast that movement occurred and whether there was any role for policy to help the process along. Neither side of the debate seriously considered the possibility that the economy would continue to move away from its long-run equilibrium outcome for a substantial period of time—for years—as a housing price bubble developed, and that once the bubble popped the interconnectedness of financial markets would cause the problem to spread in a falling domino fashion that would throw the entire economy into a deep recession.
The interesting question to me, then, is why we failed to ask the right questions. For example, notice Mr Lucas' defence of the simulations that failed to predict the crisis:
[T]he simulations were not presented as assurance that no crisis would occur, but as a forecast of what could be expected conditional on a crisis not occurring. Until the Lehman failure the recession was pretty typical of the modest downturns of the post-war period... Mr Mishkin’s forecast was a reasonable estimate of what would have followed if the housing decline had continued to be the only or the main factor involved in the economic downturn. After the Lehman bankruptcy, too, models very like the one Mr Mishkin had used, combined with new information, gave what turned out to be very accurate estimates of the private-spending reductions that ensued over the next two quarters.
I don't think we should be very impressed with the argument that once policymakers knew the economy was headed downward, the models were able to predict that the economy was headed downward. Further, even after it was known where the economy was headed, the models seriously underestimated the magnitude of the decline, and that led to an inadequate policy response.
But the important question is why policymakers didn't take the possibility of a major meltdown seriously. Why didn't they deliver forecasts conditional on a crisis occurring? Why didn't they ask this question of the model? Why did we only get forecasts conditional on no crisis? And also, why was the main factor that allowed the crisis to spread, the interconnectedness of financial markets, missed?
It was because policymakers couldn't and didn't take seriously the possibility that a crisis and meltdown could occur. And even if they had seriously considered the possibility of a meltdown, the models most people were using were not built to be informative on this question. It simply wasn't a question that was taken seriously by the mainstream.
Why did we, for the most part, fail to ask the right questions? Was it lack of imagination, was it the sociology within the profession, the concentration of power over what research gets highlighted, the inadequacy of the tools we brought to the problem, the fact that nobody will ever be able to predict these types of events, or something else?
It wasn't the tools, and it wasn't lack of imagination. As Brad DeLong points out, the voices were there—he points to Michael Mussa for one—but those voices were not heard. Nobody listened even though some people did see it coming. So I am more inclined to cite the sociology within the profession or the concentration of power as the main factors that caused us to dismiss these voices.
And here I think that thought leaders such as Robert Lucas and others who openly ridiculed models they disagreed with have questions they should ask themselves (e.g. Mr Lucas saying"At research seminars, people don’t take Keynesian theorizing seriously anymore; the audience starts to whisper and giggle to one another", or more recently "These are kind of schlock economics"). When someone as notable and respected as Robert Lucas makes fun of an entire line of inquiry, it influences whole generations of economists away from asking certain types of questions, some of which turned out to be important. Why was it necessary for the major leaders in macroeconomics to shut down alternative lines of inquiry through ridicule and other means rather than simply citing evidence in support of their positions? What were they afraid of? The goal is to find the truth, not win fame and fortune by dominating the debate.
We need to take a close look at how the sociology of our profession led to an outcome where people were made to feel embarrassed for even asking certain types of questions. People will always be passionate in defense of their life's work, so it's not the rhetoric itself that is of concern, the problem comes when factors such as ideology or control of journals and other outlets for the dissemination of research stand in the way of promising alternative lines of inquiry.
I don't know for sure the extent to which the ability of a small number of people in the field to control the academic discourse led to a concentration of power that stood in the way of alternative lines of investigation, or the extent to which the ideology that markets prices always tend to move toward their long-run equilibrium values caused us to ignore voices that foresaw the developing bubble and coming crisis. But something caused most of us to ask the wrong questions, and to dismiss the people who got it right, and I think one of our first orders of business is to understand how and why that happened.
There are other entries from (I'll update the list as more are added):
Don't fault the economists, by Robert Barro
Some successes, some failures by Tyler Cowen
Mind the frictions by Markus Brunnermeier
A change in tune by Brad DeLong
Posted by Mark Thoma on Friday, August 7, 2009 at 07:47 AM in Economics, Macroeconomics, Methodology |
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