Tuesday, May 25, 2010

An Outsider's View of Modern Macroeconomics

Following up on a testy exchange with David Andolfatto, Mark Thoma has written a thoughtful post in which he discusses the state of modern macroeconomic theory, the appropriateness of appeals to professional authority, the shortcomings of some canonical models, and the way forward. I posted a brief comment in response, with a few constructive suggestions for mainstream macroeconomists from the perspective of an outsider. I have made these points on various occasions before, and reproduce them here (slightly edited and expanded with links to earlier posts):
  1. Rational expectations is not a behavioral hypothesis, it's an equilibrium assumption and therefore much more restrictive than "forward-looking behavior". It might be justified if equilibrium paths were robustly stable under plausible specifications of disequilibrium dynamics, but this needs to be explored explicitly instead of simply being assumed. 
  2. Think about whether a theory of economic fluctuations should be shock-dependent (in the Frisch-Slutsky tradition) or shock-independent (in the Goodwin tradition). Go back and look at Goodwin's  1951 Econometrica paper to appreciate the importance of the distinction.
  3. Build models in which leverage, collateral, and default play a central role. The work of John Geanakoplos on this is an excellent starting point. He uses equilibrium theory but allows for heterogeneous priors (so differences in beliefs can persist even if they are common knowledge.) More broadly, take a close look at Hyman Minsky's integrated analysis of real and financial activity. 
  4. Do not assume that flexible wages and prices imply labor market clearing. They do in equilibrium (by definition) but wage and price flexibility in disequilibrium can make matters worse. Keynes recognized this, and Tobin explored these mechanisms formally. Arbitrary assumptions of "sticky prices" are not necessary to account for persistent unemployment or under-utilization of capacity.
  5. Finally, show some humility. There are anonymous bloggers out there, some self-taught in economics, who may know more about the functioning of a modern economy than you do.
The last point is directed at David Andolfatto, whose arrogant appeal to professional authority jolted the normally polite Mark Thoma to respond with (justifiable) belligerence. Andolfatto's entire post was dripping with condescension, but I found the following passage particularly disturbing:
DeLong tells us that we can learn a lot of economics from Krugman. You will be forgiven for wondering whether DeLong can even tell whether he is learning economics or not. DeLong is, as far as I can tell, an historian.
As I said on Mark's blog, it could be argued that economic historians (and historians of thought) have had more useful things to say about recent events than the highest of high priests in macroeconomics. Andolfatto seems to be confusing an understanding of modern macroeconomic theory with an understanding of the modern macroeconomy. The two are not the same, and the former is neither necessary nor sufficient for the latter.
Contrast the tone of Andolfatto's post with the following passage from a recent essay by Narayana Kocherlakota, president of the Minneapolis Fed:
I believe that during the last financial crisis, macroeconomists (and I include myself among them) failed the country, and indeed the world. In September 2008, central bankers were in desperate need of a playbook that offered a systematic plan of attack to deal with fast-evolving circumstances. Macroeconomics should have been able to provide that playbook. It could not. Of course, from a longer view, macroeconomists let policymakers down much earlier, because they did not provide policymakers with rules to avoid the circumstances that led to the global financial meltdown.

Because of this failure, macroeconomics and its practitioners have received a great deal of pointed criticism both during and after the crisis. Some of this criticism has come from policymakers and the media, but much has come from other economists. Of course, macroeconomists have responded with considerable vigor, but the overall debate inevitably leads the general public to wonder: What is the value and applicability of macroeconomics as currently practiced?
Kocherlakota goes on to defend the many advances made in macroeconomic research over the past four decades, but openly acknowledges the enormous challenges that remain. He goes on to say:
The seventh floor of the Federal Reserve Bank of Minneapolis is one of the most exciting macro research environments in the country. As president, I plan to learn from our staff, consultants, and visitors.
I hope that some of those visitors (real or virtual) will be voices of dissent from beyond the inner circle of research macroeconomics. It is in this spirit of openness that my comments are offered.


Update (5/26). One item that I'd like to add to the list above is methodological pluralism. For instance, there is interesting work in macroeconomics using agent-based computational methods; see, for instance, the 2008 book on Emergent Macroeconomics by Delli Gatti, Gaffeo, Gallegati, Giulioni, and Palestrini. As I have said before, such models can provide microfoundations for macroeconomics in a manner that is both more plausible and more authentic than is the case with highly aggregative representative agent models.


Update (5/26). Some useful perspective from Malaise Precis:
The dustup between Mark Thoma and David Andolfatto... is perhaps more symptomatic of the divide between - at extreme risk of too much simplification - "new" macroeconomists and "old" macroeconomists. The macroeconomists of my generation were taught DSGE models. Facts were "stylized" facts, i.e. first and second moments of "key" economic variables such as GNP, investment and consumption. During my entire 6 years at graduate school things like institutional details and historical events that may have affected the economy were laid aside or treated as not being "relevant" to the model. Economies were frictionless and markets always cleared. Sure, some frictions were eventually introduced but perhaps the biggest elephant in the room was that the curriculum cultivated us with a certain attitude that:
  1. There are those who can build DSGE models and there are those who can't.
  2. All partial equilibrium models can be dismissed off hand.
  3. All structural equation models are completely irrelevant especially those not based on DSGE models. (IS-LM or Keynesian "cross" models are definitely in this category.)
  4. Any paper that does not present a model can be dismissed - this included narratives as well as historical papers.
Perhaps the economists who fail to understand history will be doomed to repeat [it]?

Update (5/27). David Andolfatto has posted an uncommonly gracious follow-up to his earlier remarks. As Mark points out in response, "it is possible to find shrill, over the top attacks on all sides of the debate on macroeconomic policy." What bothered me about David's earlier post was not the harshness of the language but the idea that some people are simply not qualified to speak out on certain issues. I believe that we economists need (and should welcome) voices from outside our narrow areas of specialization, and indeed outside our discipline.


  1. Rajiv: I interpret David Andolfatto's post rather differently. I see him as complaining about Paul Krugman's and Brad DeLong's own lack of humility when confronting views they don't agree with. It is sadly ironic that he should be accused of what I think he was trying to speak out against.

  2. Nick, I may have misunderstood his post and failed to see through the sarcasm (since I was not previously familiar with his blog). But it was the grounds on which he was making his case - his appeal to professional authority - that bothered me.

    Take Scott Sumner, for example, as a study in contrast. He has taken on Krugman forcefully and often, but always on the basis of evidence and reasoning as he sees it, not an appeal to a certain kind of academic training. I enjoy the back-and-forth between Scott and Paul and usually learn something from it. But I've never seen either of them pull rank on the other.

    In any case, thanks for commenting... I like your blog very much.

  3. rajiv i finally had the persistence to get a comment up here
    you are running a great blog

  4. looked at the new monetary link

    seems no fisc there at all
    no wonder fiscal policy is ineffective eh ??

    i guess that's one way to defeat the fiscalist macro
    ignore it
    pretend that lever on output doesn't exist

    you retain a genteel approach to such miscreant acts

    no wonder he admires mankiw
    a real master of sly omission
    and sleight of hand comissions
    greg in fact
    would indeed
    make the perfect
    corrective idol
    for this brash chap

  5. Thanks paine, it's been fun (but exhausting at times). I haven't read the paper that Andolfatto linked to, but wouldn't be surprised if the modeling assumptions preclude welfare-improving fiscal policy. Regarding Mankiw, though, I have never heard him claim that anyone is not qualified to comment on macro policy issues simply because of their academic training or research specialization.

  6. some times the devil with the calm manner and carefully polite patter
    is far the more effective
    and greater "evil "

    i can write this with impunity

    if i were in your position i'd be a fool to bite mankiw's ankle
    in public
    andofagoolio ?
    well maybe i could
    but i understand why you haven't

    alas some one has to be "shrill"
    might as well be a faceless commando like me
    without a position to lose
    or a philosphy of universal inter personal decency to traduce

  7. Paine, my views (here and on Mark's blog) are sincerely expressed and I'm not pulling any punches. I really did think Andolfatto's response was gracious. And regarding Mankiw, I did write this a few months ago.

  8. rajiv:

    " I don't believe for a moment that anyone here is being deliberately deceptive. Mankiw clearly believes that (suitably targeted) tax cuts are a more effective fiscal policy "

    i agree in the case of tax cuts versus expenditures greg can fig leaf his class politics
    with a possible "truth"

    none the less
    i will just have to allow us to
    see him quite differently

    btw i now you are sincere
    in your
    graciousness vis a vis
    his graciousness
    in the brief
    comic bltz like

    i read your blog
    u are a very decent chap

    i'm allowable NOT !!!!

  9. Rajiv Sethi, Professor of Economics. If YOU're an outsider, what does that make me? I am certainly not "qualified to comment on macro policy issues." So, thank heavens for the First Amendment.

    One would think, since we live in such interesting times, that economists would have better things to discuss than each other's manners.

    I think the chatter has degenerated because economists are out of ideas.

    I did like your post. Otherwise I wouldna left a comment.