• Paul Krugman [2009]: “How did economists get it so wrong?”,  The New York Times, 2009-09-06.
• J. Doyne Farmer and Duncan Foley [2009]: “The economy needs agent-based modeling“,  Nature, 460, 685-686 (6 August 2009).
• Mark Buchanan [2009]:  “Economics: Meltdown modeling“, Nature, 460, 680-682 (6 August 2009).

From Krugman’s article:

“As I see it, the economics profession went astray because economists, as a group, mistook beauty, clad in impressive-looking mathematics, for truth. Until the Great Depression, most economists clung to a vision of capitalism as a perfect or nearly perfect system. That vision wasn’t sustainable in the face of mass unemployment, but as memories of the Depression faded, economists fell back in love with the old, idealized vision of an economy in which rational individuals interact in perfect markets, this time gussied up with fancy equations. The renewed romance with the idealized market was, to be sure, partly a response to shifting political winds, partly a response to financial incentives. But while sabbaticals at the Hoover Institution and job opportunities on Wall Street are nothing to sneeze at, the central cause of the profession’s failure was the desire for an all-encompassing, intellectually elegant approach that also gave economists a chance to show off their mathematical prowess.

Unfortunately, this romanticized and sanitized vision of the economy led most economists to ignore all the things that can go wrong. They turned a blind eye to the limitations of human rationality that often lead to bubbles and busts; to the problems of institutions that run amok; to the imperfections of markets — especially financial markets — that can cause the economy’s operating system to undergo sudden, unpredictable crashes; and to the dangers created when regulators don’t believe in regulation.

It’s much harder to say where the economics profession goes from here. But what’s almost certain is that economists will have to learn to live with messiness. That is, they will have to acknowledge the importance of irrational and often unpredictable behavior, face up to the often idiosyncratic imperfections of markets and accept that an elegant economic “theory of everything” is a long way off. In practical terms, this will translate into more cautious policy advice — and a reduced willingness to dismantle economic safeguards in the faith that markets will solve all problems.

 . . . .

Such Keynesian thinking underlies the Obama administration’s economic policies — and the freshwater economists are furious. For 25 or so years they tolerated the Fed’s efforts to manage the economy, but a full-blown Keynesian resurgence was something entirely different. Back in 1980, Lucas, of the University of Chicago, wrote that Keynesian economics was so ludicrous that “at research seminars, people don’t take Keynesian theorizing seriously anymore; the audience starts to whisper and giggle to one another.” Admitting that Keynes was largely right, after all, would be too humiliating a comedown.

And so Chicago’s Cochrane, outraged at the idea that government spending could mitigate the latest recession, declared: “It’s not part of what anybody has taught graduate students since the 1960s. They [Keynesian ideas] are fairy tales that have been proved false. It is very comforting in times of stress to go back to the fairy tales we heard as children, but it doesn’t make them less false.” (It’s a mark of how deep the division between saltwater and freshwater runs that Cochrane doesn’t believe that “anybody” teaches ideas that are, in fact, taught in places like Princeton, M.I.T. and Harvard.)

Meanwhile, saltwater economists, who had comforted themselves with the belief that the great divide in macroeconomics was narrowing, were shocked to realize that freshwater economists hadn’t been listening at all. Freshwater economists who inveighed against the stimulus didn’t sound like scholars who had weighed Keynesian arguments and found them wanting. Rather, they sounded like people who had no idea what Keynesian economics was about, who were resurrecting pre-1930 fallacies in the belief that they were saying something new and profound.

And it wasn’t just Keynes whose ideas seemed to have been forgotten. As Brad DeLong of the University of California, Berkeley, has pointed out in his laments about the Chicago school’s “intellectual collapse,” the school’s current stance amounts to a wholesale rejection of Milton Friedman’s ideas, as well. Friedman believed that Fed policy rather than changes in government spending should be used to stabilize the economy, but he never asserted that an increase in government spending cannot, under any circumstances, increase employment. In fact, rereading Friedman’s 1970 summary of his ideas, “A Theoretical Framework for Monetary Analysis,” what’s striking is how Keynesian it seems.

And Friedman certainly never bought into the idea that mass unemployment represents a voluntary reduction in work effort or the idea that recessions are actually good for the economy. Yet the current generation of freshwater economists has been making both arguments. Thus Chicago’s Casey Mulligan suggests that unemployment is so high because many workers are choosing not to take jobs: “Employees face financial incentives that encourage them not to work . . . decreased employment is explained more by reductions in the supply of labor (the willingness of people to work) and less by the demand for labor (the number of workers that employers need to hire).” Mulligan has suggested, in particular, that workers are choosing to remain unemployed because that improves their odds of receiving mortgage relief. And Cochrane declares that high unemployment is actually good: “We should have a recession. People who spend their lives pounding nails in Nevada need something else to do.”

Personally, I think this is crazy. Why should it take mass unemployment across the whole nation to get carpenters to move out of Nevada? Can anyone seriously claim that we’ve lost 6.7 million jobs because fewer Americans want to work? But it was inevitable that freshwater economists would find themselves trapped in this cul-de-sac: if you start from the assumption that people are perfectly rational and markets are perfectly efficient, you have to conclude that unemployment is voluntary and recessions are desirable.

Yet if the crisis has pushed freshwater economists into absurdity, it has also created a lot of soul-searching among saltwater economists. Their framework, unlike that of the Chicago School, both allows for the possibility of involuntary unemployment and considers it a bad thing. But the New Keynesian models that have come to dominate teaching and research assume that people are perfectly rational and financial markets are perfectly efficient. To get anything like the current slump into their models, New Keynesians are forced to introduce some kind of fudge factor that for reasons unspecified temporarily depresses private spending. (I’ve done exactly that in some of my own work.) And if the analysis of where we are now rests on this fudge factor, how much confidence can we have in the models’ predictions about where we are going?”

There were six papers accepted for the special issue after peer-review by anonymous reviewers:  

• Borissov N, Neumann D, Weinhardt C: Automated bidding in computational markets: An application in market-based allocation of computing services.
• Lewis PR, Marrow P, Yao X: Resource allocation in decentralised computational systems: An evolutionary market-based approach.
• Niu J, Cai K, Parsons S, McBurney P, Gerding E: What the 2007 TAC Market Design Game tells us about effective auction mechanisms.
• Sarne D, Manisterski E, Kraus S:  Multi-goal economic search using dynamic search structures.  
• Phelps S, McBurney P, Parsons S: Evolutionary mechanism design: A review.
• Vetsikas IA, Jennings NR: Bidding strategies for realistic multi-unit sealed-bid auctions.

We are very grateful to all those submitted papers to the special issue and to the preceeding international workshop, and to those who undertook peer reviews of the submissions.  The papers will be available from the journal web-pages in due course.

“But as the business grew, Kamangar and Veach decided to price the slots on the side of the page by means of an auction. Not an eBay-style auction that unfolds over days or minutes as bids are raised or abandoned, but a huge marketplace of virtual auctions in which sealed bids are submitted in advance and winners are determined algorithmically in fractions of a second. Google hoped that millions of small and medium companies would take part in the market, so it was essential that the process be self-service. Advertisers bid on search terms, or keywords, but instead of bidding on the price per impression, they were bidding on a price they were willing to pay each time a user clicked on the ad. (The bid would be accompanied by a budget of how many clicks the advertiser was willing to pay for.) The new system was called AdWords Select . . .” 

“Since the 1970s economists have been engaged in a grand project. The project’s objective is that macroeconomics should have microeconomic foundations. In everyday language, that means that what we say about big policy issues – growth and inflation, boom and bust – should be grounded in the study of individual behaviour. Put like that, the project sounds obviously desirable, even essential. I confess I was long seduced by it.

Most economists would claim that the project has been a success. But the criteria are the self-referential criteria of modern academic life. The greatest compliment you can now pay an economic argument is to say it is rigorous. Today’s macroeconomic models are certainly that.

But policymakers and the public at large are, rightly, not interested in whether models are rigorous. They are interested in whether the models are useful and illuminating – and these rigorous models do not score well here.

Indeed, at an early stage of the project Robert Lucas, one of its principal architects, who received the Nobel prize for his contributions, developed what is known as the Lucas critique. He argued that ordinary standards of statistical validity should not be applied to the project’s predictions. According to his colleague Thomas Sargent, Lucas was concerned that such tests rejected “too many really good models”.

Economists, like physicists, have been searching for a theory of everything. If there were to be such an economic theory, there is really only one candidate, based on extreme rationality and market efficiency. Any other theory would have to account for the evolution of individual beliefs and the advance of human knowledge, and no one imagines that there could be a single theory of all human behaviour. Not quite no one: a few deranged practitioners of the project believe that their theory really does account for all human behaviour, and that concepts such as goodness, beauty and truth are sloppy sociological constructs.

But these people discredit themselves by opening their mouths. That people respond rationally to incentives, and that market prices incorporate information about the world, are not terrible assumptions. But they are not universal truths either. Much of what creates profit opportunities and causes instability in the global economy results from the failure of these assumptions. Herd behaviour, asset mispricing and grossly imperfect information have led us to where we are today.”

(Hat tip:  SP)