Tom Sargent describes how he learnt macroeconomics the Lucas way, starting from the Cowles Commission approach and digesting Muth’s (or Richardson’s?) rational expectations.
MA course at the University of Bern.
Time: Wed 10-12. Location: A-126 UniS. Course assistant: Stefano Corbellini.
The course introduces Master students to modern macroeconomic theory. Building on the analysis of the consumption-saving tradeoff and on concepts from general equilibrium theory, the course covers workhorse general equilibrium models of modern macroeconomics, including the representative agent framework, the overlapping generations model, and the Lucas tree model. Lectures follow chapters 1–4 (possibly 5) in this book.
SARS-COV 2: Until further notice the course is offered on-site. It is our joint responsibility to reduce the risk of infection in class. Only students who satisfy two criteria should attend class: (i) They should not feel ill and (ii) they should be fully vaccinated or should recently have recovered from an infection or should have very recently tested negative. Students who do not satisfy (i) and (ii) should follow the class via podcast.
MA course at the University of Bern.
Time: Wed 10-12. KSL course site. Course assistant: Armando Näf.
The course introduces Master students to modern macroeconomic theory. Building on the analysis of the consumption-saving tradeoff and on concepts from general equilibrium theory, the course covers workhorse general equilibrium models of modern macroeconomics, including the representative agent framework, the overlapping generations model, and possibly the Lucas tree model. Lectures follow chapters 1–4 (possibly 5) in this book.
PDF copy of what I scribbled in class.
VoxEU, June 22, 2020. HTML.
Is macroeconomics useful? Of course. To make the point, academics must regain the interpretative high ground from market commentators. While it helps when policymakers understand fundamental macroeconomic concepts, it is equally important for the general public to grasp them. More, and how this relates to the new textbook, on VoxEU.
Macroeconomic Analysis available at Rakuten.
Forthcoming, MIT Press. Book page.
Forthcoming, MIT Press. Book page.
Forthcoming, MIT Press. Book page.
“An orderly and elegant presentation of essential ideas of modern macroeconomics with a perfect mix of tools and applications.”
—Thomas Sargent, Professor of Economics, New York University
(To be continued.)
Forthcoming, MIT Press. Book page.
Arnold Kling (2016), Specialization and Trade, A Re-Introduction to Economics, Washington, DC, Cato Institute.
Kling’s central theme in this short book of nine main chapters is that specialization, trade, and the coordination of individual plans by means of the price system and the profit motive play fundamental roles in modern economies. Most mainstream economists would agree with this assessment. Their models of trade, growth, and innovation certainly include the four elements, with varying emphasis.
But Kling criticizes the methodological approach adopted by post-world-war-II economics, which he associates with “MIT economics.” An MIT PhD himself, he argues that economics, and specifically macroeconomics, should adopt less of a mechanistic and more of an evolutionary perspective to gain relevance. In the second chapter, entitled “Machine as Metaphor,” Kling asserts that under the leadership of Paul Samuelson post-war (macro)economics framed economic issues as programming problems that resemble resource allocation problems in a wartime economy. Even as the discipline evolved, Kling contends, the methodology remained the same, pretending controllability by economist-engineers; in the process, the role of specialization was sidelined in the analysis.
I think that Kling is too harsh in his assessment. Economics and macroeconomics, in particular, has changed dramatically since the times of Paul Samuelson. The notion that, given enough instruments, any economic problem can be solved as easily as a system of equations, has lost attraction. Modern macroeconomic models are based on microeconomic primitives; they take gains from trade seriously; they involve expectations and frictions; and they do not suggest easy answers. The task of modern macroeconomics is not to spit out a roadmap for the economist-engineer but to understand mechanisms and identify problems that arise from misaligned incentives.
Kling is right, of course, when he argues that many theoretical models are too simplistic to be taken at face value. But this is not a critique against economic research which must focus and abstract in order to clarify. It rather is a critique against professional policy advisors and forecasters, “economic experts” say. These “experts” face the difficult task of surveying the vast variety of mechanisms identified by academic research and to apply judgement when weighing their relevance for a particular real-world setting. To be useful, “experts” must not rely on a single framework and extrapolation. Instead, they must base their analysis on a wide set of frameworks to gain independent perspectives on a question of interest.
In chapters three to five, Kling discusses in more detail the interplay of myriads of specialized trading partners in a market economy and how prices and the profit motive orchestrate it. In the chapter entitled “Instructions and Incentives,” Kling emphasizes that prices signal scarcity and opportunity costs are subjective. In the chapter entitled “Choices and Commands,” he discusses that command-and-control approaches to organizing a society face information, incentive, and innovation problems, unlike approaches that rely on a functioning price mechanism. And in the chapter “Specialization and Sustainability,” Kling makes the point that well-defined property rights and a functioning price mechanism offer the best possible protection for scarce resources and a guarantee for their efficient use. Sustainability additionally requires mechanisms to secure intergenerational equity.
I agree with Kling’s point that we should be humble when assessing whether market prices, which reflect the interplay of countless actors, are “right” or “wrong.” However, I would probably be prepared more often than Kling to acknowledge market failures of the type that call for corrective taxes. The general point is that Kling’s views expressed in the three chapters seem entirely mainstream. While we may debate how often and strongly market prices fail to account for social costs and benefits, the economics profession widely agrees that for a price system to function well this precondition must be satisfied.
In the sixth chapter, entitled “Trade and Trust,” Kling argues that specialization rests on cultural evolution and learning and more broadly, that modern economic systems require institutions that promote trust. Independently of the norms a particular society adopts, it must implement the basic social rule,
[r]eward cooperators and punish defectors.
How this is achieved (even if it is against the short-run interest of an individual) varies. Incentive mechanisms may be built on the rule of law, religion, or reputation. And as Kling points out societies almost always rely on some form of government to implement the basic social rule. In turn, this creates problems of abuse of power as well as “deception” and “demonization.” Mainstream economists would agree. In fact, incentive and participation constraints, lack of commitment, enforcement, and self-enforcement are at center stage in many of their models of partial or general equilibrium. Similarly, the role of government, whether benevolent or representing the interests of lobby groups and elites, is a key theme in modern economics.
Chapter seven, entitled “Finance and Fluctuations,” deals with the role of the financial sector. Kling argues that finance is a key prerequisite for specialization and since trust is a prerequisite for finance, swings in trust—waves of optimism and pessimism—affect the economy. No mainstream macroeconomist will object to the notion that the financial sector can amplify shocks. Seminal articles (which all were published well before the most recent financial crisis) exactly make that point. But Kling is probably right that the profession’s workhorse models have not yet been able to incorporate moods, fads, and manias, the reputation of intermediaries, and the confidence of their clients in satisfactory and tractable ways, in spite of recent path-breaking work on the role of heterogenous beliefs.
In chapter eight, Kling focuses on “Policy in Practice.” He explains why identifying market failure in a model is not the same as convincingly arguing for government intervention, simply because first, the model may be wrong and second, there is no reason to expect government intervention to be frictionless. I don’t know any well-trained academic economist who would disagree with this assessment (but many “experts” who are very frighteningly confident about their level of understanding). The profession is well aware of the insights from Public Choice and Political Economics, although these insights might not be as widely taught as they deserve. And Kling is right that economists could explain better why real-world policy selection and implementation can give rise to new problems rather than solely focusing on the issue of how an ideal policy might improve outcomes.
To me, the most interesting chapters of the book are the first and the last, entitled “Filling in Frameworks” and “Macroeconomics and Misgivings,” respectively. In the first chapter, Kling discusses the difference between the natural sciences and economics. He distinguishes between scientific propositions, which a logical flaw or a contradictory experiment falsifies, and “interpretive frameworks” a.k.a. Kuhn’s paradigms, which cannot easily be falsified. Kling argues that
[i]n natural science, there are relatively many falsifiable propositions and relatively few attractive interpretive frameworks. In the social sciences, there are relatively many attractive interpretive frameworks and relatively few falsifiable propositions.
According to Kling, economic models are interpretative frameworks, not scientific propositions, because they incorporate a plethora of auxiliary assumptions and since experiments of the type run in the natural sciences are beyond reach in the social sciences. Anomalies or puzzles do not lead economists to reject their models right away as long as the latter remain useful paradigms to work with. And rightly so, according to Kling: For an interpretative framework with all its anomalies is less flawed than intuition which is uninformed by a framework. At the same time, economists should remain humble, acknowledge the risk of confirmation bias, and remain open to competing interpretative frameworks.
In the chapter entitled “Macroeconomics and Misgivings,” Kling criticizes macroeconomists’ reliance on models with a representative agent. I agree that representative agent models are irrelevant for applied questions when the model implications strongly depend on the assumption that households are literally alike, or that markets are complete such that heterogeneous agents can perfectly insure each other. When “experts” forecast macroeconomic outcomes based on models with a homogeneous household sector then these forecasts rest on very heroic assumptions, as any well-trained economist will readily acknowledge. Is this a problem for macroeconomics which, by the way, has made a lot of progress in modeling economies with heterogeneous agents and incomplete markets? I don’t think so. But it is a problem when “experts” use such inadequate models for policy advice.
Kling argues that the dynamic process of creative destruction that characterizes modern economies requires ongoing change in the patterns of specialization and trade and that this generates unemployment. Mainstream models of innovation and growth capture this process, at least partially; they explain how investment in new types of capital and “ideas” can generate growth and structural change. And the standard framework for modeling labor markets features churn and unemployment (as well as search and matching) although, admittedly, it does not contain a detailed description of the sources of churn. The difference between the mainstream’s and Kling’s view of how the macroeconomy operates thus appears to be a difference of degree rather than substance. And the difference between these views and existing models clearly also reflects the fact that modeling creative destruction and its consequences is difficult.
Kling is a sharp observer when he talks about the difference between “popular Keynesianism” and “rigor-seeking Keynesianism.” The former is what underlies the thinking of many policy makers, central bankers, or journalists: a blend of the aggregate-demand logic taught to undergraduates and some supply side elements. The latter is a tractable simplification of a micro-founded dynamic general equilibrium model with frictions whose properties resemble some key intuitions from popular Keynesianism.
The two forms of Keynesianism help support each other. Popular Keynesianism is useful for trying to convince the public that macroeconomists understand macroeconomic fluctuations and how to control them. Rigor-seeking Keynesianism is used to beat back objections raised by economists who are concerned with the ways in which Keynesianism deviates from standard economics, even though the internal obsessions of rigor-seeking Keynesianism have no traction with those making economic policy.
There is truth to this. But in my view, this critique does not undermine the academic, rigor-seeking type of Keynesianism while it should undermine our trust in “experts” who work with the popular sort which, as Kling explains, mostly is confusing for a trained economist.
In the end, Kling concludes that it is the basics that matter most:
[B]etter economic outcomes arise when patterns of sustainable specialization and trade are formed. … It requires the creative, decentralized, trial-and-error efforts of thousands of entrepreneurs and millions of households … Probably the best thing that the government can do to encourage new forms of specialization is to rethink existing policies that restrict competition, discourage innovation, and retard mobility.
This is a reasonable conclusion. But it is neither a falsifiable proposition nor an interpretive framework. It is the synthesis of many interpretive frameworks, weighed by Kling. In my own view, the weighting is based on too harsh an assessment according to which many modern macroeconomic models are irrelevant.
Kling’s criticism of contemporaneous macroeconomics reads like a criticism of the kind of macroeconomics still taught at the undergraduate level. But modern macroeconomics has moved on—it is general equilibrium microeconomics. Its primary objective is not to produce the one and only model for economist-engineers or “experts” to use, but rather to help us understand mechanisms. A good expert knows many models, is informed about institutions, and has the courage to judge which of the models (or mechanisms they identify) are the most relevant in a specific context. We don’t need a new macroeconomics. But maybe we need better “experts.”
Festschrift in Honour of Ernst Baltensperger, Swiss National Bank/Orell Füssli, Zürich, June 2017, with Thomas Moser, Carlos Lenz, and Marcel Savioz, editorial committee. Publisher’s website.
From the publisher’s website:
»Eine Welt ohne ein gut funktionierendes Zahlungssystem, ohne Geld- und andere Wertaufbewahrungsanlagen, ohne zuverlässige Recheneinheit, das wäre eine Welt mit einem viel tieferen Wohlstandsniveau,in der wir nicht mehr leben möchten.«
Ursachen und Folgen der Finanzkrise sind komplex. Zentralbanken und Regulatoren sahen sich gezwungen, in vielerlei Hinsicht unbekanntes Terrain zu betreten. Die ökonomische Forschung wurde mit vielen neuen, oft grundlegenden Fragen zum Finanzsystem und zur Wirtschaftspolitik konfrontiert und ringt bis heute um Antworten.
Diese Festschrift gibt zehn Jahre nach dem Ausbruch der Finanzkrise einen Einblick in die Fragen, mit denen sich die monetäre Ökonomie heute befasst. Sie wird von der Schweizerischen Nationalbank zum 75. Geburtstag von Ernst Baltensperger – einem international renommierten Experten der Geldpolitik und Geldtheorie – herausgegeben.
Elektronisches Geld, unkonventionelle Geldpolitik, negative Zinsen – mit welchen Fragen befasst sich die Wirtschaftswissenschaft heute, und welche Antworten liefert sie?
27 Beiträge von Experten der Makro-, Geld-, Banken und Finanzmarktökonomie für ein besseres Verständnis der Zusammenhänge und Strukturen.
Die kurze und allgemein verständlichen Texte sind für den interessierten Laien – auf Deutsch, Französisch oder Englisch verfasst.
In a paper, Ricardo Reis defends macroeconomics against various critiques. He concludes:
I have argued that while there is much that is wrong with macroeconomics today, most critiques of the state of macroeconomics are off target. Current macroeconomic research is not mindless DSGE modeling filled with ridiculous assumptions and oblivious of data. Rather, young macroeconomists are doing vibrant, varied, and exciting work, getting jobs, and being published. Macroeconomics informs economic policy only moderately and not more nor all that differently than other fields in economics. Monetary policy has benefitted significantly from this advice in keeping inflation under control and preventing a new Great Depression. Macroeconomic forecasts perform poorly in absolute terms and given the size of the challenge probably always will. But relative to the level of aggregation, the time horizon, and the amount of funding, they are not so obviously worst than those in other fields. What is most wrong with macroeconomics today is perhaps that there is too little discussion of which models to teach and too little investment in graduate-level textbooks.
The “Trouble with Macroeconomics,” according to a working paper by Paul Romer that is posted on his website, relates to dishonest identification assumptions, in particular in DSGE models used for policy analysis. Romer singles out calibration, assumptions about distribution functions and strong priors as culprits.
Romer argues that
[b]eing a Bayesian means that your software never barfs
I agree with the harsh judgment by Lucas and Sargent (1979) that the large Keynesian macro models of the day relied on identifying assumptions that were not credible. The situation now is worse. Macro models make assumptions that are no more credible and far more opaque.
Romer also offers a meta-model of himself as a critic of “post-real models” and “facts with unknown truth value.”
Three opinion leaders in the blogosphere have laid out how they think about the macroeconomy. They talk about “models” but unfortunately don’t deliver. Instead, they provide lists of beliefs or facts to be explained. Economics is a science precisely because it has progressed beyond such lists. Economists build models—consistent, well-structured and clearly specified (and thus, mathematically formulated) stories.
But here are the lists: Scott Sumner’s “Musical Chairs model” (blog):
In the short run, employment fluctuations are driven by variations in the NGDP/Wage ratio.
Monetary policy drives NGDP, by influencing the supply and demand for base money.
Nominal wages are sticky in the short run, and hence NGDP shocks cause variations in employment in the same direction.
In the long run, wages are flexible and adjust to changes in NGDP. Unemployment returns to the natural rate (currently about 5% in the US.)
Tyler Cowen’s “model” (blog):
In world history, 99% of all business cycles are real business cycles. No criticism of RBC can change this fact. Furthermore the propagation mechanism for a “Keynesian business cycle” (arguably a misleading phrase) also relies on RBC theory.
In the more recent segment of world history, a lot of cycles have been caused by negative nominal shocks. I consider the Christina and David Romer “shock identification” paper (pdf, and note the name order) to be one of the very best pieces of research in all of macroeconomics. Sometimes central banks tighten when they shouldn’t, and this leads to a recession, due mainly to nominal wage stickiness.
Workers are laid off because employers are often (not always) afraid to cut their nominal wages, for fear of busting workplace morale, or in Europe often for legal and union-related reasons.
Overall I favor a nominal gdp rule for monetary policy. But most of its gains would come in a few key historical episodes, such as 1929-1932, or 2008-2009. In most periods I don’t think we know what the correct monetary policy should be, nor do we know that it matters. Still, that uncertainty does not militate against an ngdp rule.
Once workers are unemployed, nominal wage stickiness is no longer the main reason why they stay unemployed. In fact nominal wage stickiness is largely taken out of the equation because there is no preexisting nominal wage contract for these workers. There may, however, be some residual stickiness due to irrational reservation wages, also known as voluntary unemployment due to stupidity. (You will find a different perspective in Scott’s musical chairs model, which I may cover more soon.)
Monetary stimulus to be effective needs to be applied very early in the job destruction process of a recession. It is much harder to put the pieces back together again, so urgency is of the essence.
The successful reemployment of workers depends upon a matching problem, a’la Pissarides, Mortensen, and others. Yet this matching problem is poorly understood, and it can involve a mix of nominal and real imperfections. Sometimes it is solved more quickly than expected, such as in the recent UK experience, and other times more slowly than expected, as in current Spain. Most of the claims you will read about this reemployment of workers are wrong, enslaved to ideology or dogmatism, or at the very least unjustified. Hardly anyone wants to admit this.
Really bad recessions involve deficient aggregate demand, negative shocks to intermediation, some chronic supply-side problems, negative wealth effects, and increases in the risk premium, all together. It is hard to find a quick fix. Furthermore models where AS and AD curves are independent and separable are often misleading, despite their analytic convenience.
Given that weak AD is only one of the problems in a bad downturn, and that confidence, risk, and supply side problems matter too, the best question to ask about fiscal policy is how well the money is being spent. The “jack up AD no matter” approach is, in the final political equilibrium, not doing good fiscal policy any favors.
You should neither rule out nor overstate the relevance of Hayek and Minsky. Their views have much in common, despite the difference in ideological mood affiliation and who — government or the market — gets blamed for the downturn. For really bad recessions, usually both institutions are complicit to say the least.
The Economist’s Free Exchange response to Cowen’s model (blog):
Supply-side policy is hard. Why is America the richest large economy in the world? Well, because output per person has grown at about 2% per year, on average, for a very long time. How did it manage that? I have a long list of policy choices and characteristics and historical accidents that I believe contributed, but I would find it very difficult to say which of those factors were most important. If someone gave me free reign over the German economy and asked me to raise its output per person to American levels, I know the sorts of things I would do, but I have a low level of confidence that I could succeed, or even close much of the gap, within a generation.
That doesn’t mean that supply-side policy should be ignored. Supply-side reforms (of the sort this newspaper tends to favour) are politically difficult to achieve, but many of them are probably at least somewhat useful and should be undertaken whenever the political environment is amenable (though with very modest expectations regarding detectable effects on growth).
With supply-side policy, the precision of a policy action is not the problem; accuracy is. With demand-side policy, it is the opposite: it is pretty easy to meet broad policy goals, so long as you’re not too concerned about hitting them square on the nose.
We know what an economy with way too much demand looks like. It has high and accelerating inflation.
We know what an economy with way too little demand looks like. It has high unemployment and deflation.
Within those two extremes, it can be tricky to identify exactly where an economy stands: how close or far away from potential output it is.
Both too much and too little demand are economically costly, but history suggests that too little demand is far more economically costly and politically risky than too much demand. So policy should err on the side of too much demand rather than too little.
The determined use of monetary policy is almost always going to be sufficient to generate the right sort of “too much demand”. But an independent central bank might not always be able to muster the appropriate determination. In some cases a central bank may flounder until a clear political consensus emerges supporting the determined use of monetary policy.
It is generally unwise for countries to sacrifice monetary-policy autonomy, either by adopting a constraining exchange-rate regime or by introducing an excessive level of capital-account openness.
In countries with autonomous monetary policy, which are stuck at the zero lower bound on interest rates, fiscal policy is almost by definition too tight, and it is probably quite difficult to conduct fiscal stimulus in a way that generates long-run economic costs. That is because the long-run supply-side and fiscal benefits of getting off the ZLB are probably pretty large.
Fiscal policy is subject to political constraints, and it may be easier to introduce a large stimulus in emergency situations if the pre-emergency public-debt burden is low. That suggests that prudence in normal times is a good idea (though do remember point number 10).
Don’t subsidise debt.
The level of financial- and banking-sector liberalisation at which it can be demonstrated persuasively that further liberalisation will generate net benefits is probably not that high.
In a Vox column, Olivier Blanchard distills ten takeaways from an IMF conference on “Rethinking Macro Policy. Progress or Confusion?’” He lists them under the following headings:
- What will be the ‘new normal’?
- What the new normal will be matters a lot for policy design
- Can we hope to limit systemic financial risk?
- Should monetary policy go back to its old ways?
- Instrument rules
- Macroprudential tools or financial regulation
- Should central banks keep their independence?
- Little progress on the design of fiscal policy
- The complex effects of capital flows
- How much can the international monetary system be improved?