ニューヨーク市立大学の経済学助教授のJ.W. Masonが、7/2のこちらのパネル討論のために用意した表題の小論をEvonomicsに上げている(原題は「Five Ways to Build a New Macroeconomics」、H/T Mostly Economics)。

Jón Steinsson wrote up some thoughts for this panel about the current state of macroeconomics. He begins:

There is a narrative within our field that macroeconomics has lost its way. While I have some sympathy with this narrative, I think it is a better description of the field 10 years ago than of the field today. Today, macroeconomics is in the process of regaining its footing. Because of this, in my view, the state of macroeconomics is actually better than it has been for quite some time.

I can’t help but be reminded of Olivier Blanchard’s 2008 article on the state of macroeconomics, which opened with a flat assertion that “the state of macro is good.” I am not convinced today’s positive assessment is going to hold up better than that one.
Where I do agree with Jón is that empirical work in macro is in better shape than theory. But I think theory is in much worse shape than he thinks. The problem is not some particular assumptions. It is the fundamental approach.
We need to be brutally honest: What is taught in today’s graduate programs as macroeconomics is entirely useless for the kinds of questions we are interested in.
I have in front of me the macro comprehensive exam from a well-regarded mainstream economics PhD program. The comp starts with the familiar Euler equation with a representative agent maximizing their utility from consumption over an infinite future. Then we introduce various complications — instead of a single good we have a final and intermediate good, we allow firms to have some market power, we introduce random variation in the production technology or markup. The problem at each stage is to find what is the optimal path chosen by the representative household under the new set of constraints.
This is what macroeconomics education looks like in 2021. I submit that it provides no preparation whatsoever for thinking about the substantive questions we are interested in. It’s not that this or that assumption is unrealistic. It is that there is no point of contact between the world of these models and the real economies that we live in.
I don’t think that anyone in this conversation reasons this way when they are thinking about real economic questions. If you are asked how serious inflation is likely to be over the next year, or how much of a constraint public debt is on public spending, or how income distribution is likely to change based on labor market conditions, you will not base your answer on some kind of vaguely analogous questions about a world of rational households optimizing the tradeoff between labor and consumption over an infinite future. You will answer it based on your concrete institutional and historical knowledge of the world we live in today.
To be sure, once you have come up with a plausible answer to a real world question, you can go back and construct a microfounded model that supports it. But so what? Yes, with some ingenuity you can get a plausible Keynesian multiplier out of a microfounded model. But in terms of what we actually know about real economies, we don’t learn anything from the exercise that the simple Keynesian multiplier didn’t already tell us.
The heterogenous agent models that Jón talks about are to me symptoms of the problem, not signs of progress. You start with a fact about the world that we already knew, that consumption spending is sensitive to current income. Then you backfill a set of microfoundations that lead to that conclusion. The model doesn’t add anything, it just gets you back to your starting point, with a lot of time and effort that you could have been using elsewhere. Why not just start from the existence of a marginal propensity to consume well above zero, and go forward from there?
Then on the other hand, think about what is not included in macroeconomics education at the graduate level. Nothing about national accounting. Nothing about about policy. Nothing about history. Nothing about the concrete institutions that structure real labor and product markets.
My personal view is that we need to roll back the clock at least 40 years, and throw out the whole existing macroeconomics curriculum. It’s not going to happen tomorrow, of course. But if we want a macroeconomics that can contribute to public debates, that should be what we’re aiming for.
What should we be doing instead? There is no fully-fledged alternative to the mainstream, no heterodox theory that is ready to step in to replace the existing macro curriculum. Still, we don’t have to start from scratch. There are fragments, or building blocks, of a more scientific macroeconomics scattered around. We can find promising approaches in work from earlier generations, work in the margins of the profession, and work being done by people outside of economics, in the policy world, in finance, in other social sciences.
This work, it seems to me, shares a number of characteristics.


確かに、現実世界の問題について説得力のある回答を思いついたら、理論に立ち返って、それを裏付けるミクロ的基礎付けを持つモデルを構築することができる。しかし、だからどうだというのだ? 確かに工夫をすれば、ミクロ的基礎付けを持つモデルから納得の行くケインズ経済学の乗数を得ることができる。しかし現実経済について我々が実際に知っていることという観点からすれば、単純なケインズ経済学の乗数が既に教えてくれたこと以上のことをその演習から学ぶことはできない。
では、取りあえずはどうすれば良いか? 主流派に取って代わる完全な選択肢は存在しない。既存のマクロ経済学教育課程を置き換える用意のある異端理論は存在しないのだ。とは言え、一から始める必要はない。より科学的なマクロ経済学の破片ないし構成要素は辺りに散らばっている。前の世代の研究から有望な手法を見つけることができる。そうした研究は、学界の周縁に位置していた研究や、政策やファイナンスや他の社会学など経済学の外の人々によってなされた研究である。


  1. 幅広い公けの議論と密接に関連している
    • 我々は、経済の一般理論を追い求めているのではなく、特定の問題に特化した多数のモデルを追い求めている。
  2. 国民経済計算が中心にある
    • 大学院教育は現行の国民経済計算とデータ収集の理解を深めることに重点を置くべき。
  3. 基本的に集約変数を対象とする
    • 「誘導型」モデルを軽視する傾向は無くすべき。
  4. 歴史を扱う
    • 経済学の一般法則なるものはほとんど存在せず、あるのは特定の時間と空間において多少なりとも一貫したパターンのみ。
  5. 金融を扱う
    • 仮想的な非貨幣経済モデルは現実経済について信頼できる洞察を生み出すことはない。


In my ideal world, a macroeconomics education would proceed like this. First, here are the problems the external world is posing to us — the economic questions being asked by historians, policy makers, the business press. Second, here is the observable data relevant to those questions, here’s how the variables are defined and measured. Third, here are how those observables have evolved in some important historical cases. Fourth, here are some general patterns that seem to hold over a certain range — and just as important, here is the range where they don’t. Finally, here are some stories that might explain those patterns, that are plausible given what we know about how economic activity is organized.


  1. 学界のマクロ経済学が公けの議論との接点を失いつつある
    • 政策担当者はかつてほど主流派経済理論に敬意を払わなくなっている
  2. ミクロ的基礎付けが必要というダムが決壊すれば、一般均衡を追い求める風習が無くなる方向に一気に話が進むのではないか


Keynes got a lot of things right, but one thing I think he got wrong was that “practical men are slaves to some defunct economist.” The relationship is more often the other way round. When practical people come to think about economy in new ways, economic theory eventually follows.

*1:cf. ここ

*2:cf. ここで紹介したロバート・ワルドマンの議論。