July 2016 – J. W. Mason

Links for July 27, 2016

Labor dynamism and demand. My colleagues Mike Konczal and Marshall Steinbaum have an important new paper out on the decline in new business starts and in labor mobility. They argue that the data don’t support a story where declining labor-market dynamism is the result of supply-side factors like occupational licensing. It looks much more like the result of chronically weak demand for labor, which for whatever reason is not picked up by the conventional unemployment rate. This is obviously relevant to the potential output question I’m interested in — a slowdown in the rate at which workers move to new firms is a natural channel by which weak demand could reduce labor productivity. It’s also a very interesting story in its own right.

Konczal and Steinbaum:

The decline of entrepreneurship and “business dynamism” has become an accepted fact … Explanations for these trends … broadly fall on the supply side: that increasingly onerous occupational licensing impedes entry into certain protected professions and restricts licensed workers to staying where they are; that the high cost of housing thanks to restrictions on development hampers individuals from moving… But we find that the data reject these supply-side explanations: If there were increased restrictions on changing jobs or starting a business, we would expect those few workers and entrepreneurs who do manage to move to enjoy increased wage gains relative to periods with higher worker flows, and we would expect aggressive hiring by employers with vacancies. … Instead, we see the opposite…

We propose a different organizing principle: Declining business dynamism and labor mobility are features of a slackening labor market … workers lucky enough to have formal employment stay where they are rather than striking out as entrepreneurs …

Also in Roosevelt news, here’s a flattering piece about us in the New York Times Magazine.

John Kenneth who? Real World Economics Review polled its subscribers on the most important economics books of the past 100 years. Here’s the top ten. Personally I suspect Debt will have more staying power than Capital in the 21st Century, and I think Minsky’s book John Maynard Keynes is a better statement of his vision than Stabilizing an Unstable Economy, a lot of which is focused on banking-sector developments of the 1970s and 1980s that aren’t of much interest today. But overall it’s a pretty good list. The only one I haven’t read is The Affluent Society. I wonder if anyone under the age of 50 picked that one?

Deflating the elephant. Here is a nice catch from David Rosnick. Brank Milanovic has a well-known graph of changes in global income distribution over 1988-2008. What we see is that, while within most countries there has been increased polarization, at the global level the picture is more complicated. Yes, the top of the distribution has gone way up, and the very bottom has gone down. But the big fall has been in the upper-middle of the distribution — between the 80th and 99th percentiles — while most of the lower part has has risen, with the biggest gains coming around the 50th percentile. The decline near the high end is presumably working-class people in rich countries and most people in the former Soviet block —who were still near the top of the global distribution in 1988. A big part of the rise in the lower half is China. A natural question is, how much? — what would the distribution look like without China? Milanovic had suggested that the overall picture is still basically the same. But as Rosnick shows, this isn’t true — if you exclude China, the gains in the lower half are much smaller, and incomes over nearly half the distribution are lower in 2008 than 20 years before. It’s hard to see this as anything but a profoundly negative verdict on the Washington Consensus that has ruled the world over the past generation.

By the way, you cannot interpret this — as I at first wrongly did — as meaning that 40 percent of the world’s people have lower incomes than in 1988. It’s less than that. Faster population growth in poor countries would tend to shift the distribution downward even if every individual’s income was rising.

Does nuclear math add up? Over at Crooked Timber, there’s been an interesting comments-thread debate between Will Boisvert (known around here for his vigorous defense of nuclear power) and various nuke antis and skeptics. I’m the farthest thing from an expert, I can’t claim to be any kind of arbiter. But personally my sympathies are with Will. One important thing he brings out, which I hadn’t thought about enough until now, is the difference between electricity and most other commodities. Part of the problem is the very large share of fixed costs — as the Crotty-Minsky-Perelman strain of Keynesians have emphasized, capitalism does badly with long lived capital assets. A more distinctive problem is the time dimension — electricity produced at one time is not a good substitute for electricity produced at a different time, even just an hour before or after. Electricity cannot be stored economically at a meaningful scale, nor — given that almost everything in modern civilization uses it — can its consumption be easily shifted in time. This means that straightforward comparisons of cost per kilowatt — hard enough to produce, given the predominance of fixed costs — can be misleading. Regardless of costs, intermittent sources — like wind or solar — have to be balanced by sources that can be turned on anytime — which in the absence of nuclear, means fossil fuels.

Do you believe, as I do, that climate change is the great challenge facing humanity in the next generation? Then this is a very strong argument for nuclear power. Whatever its downsides, they are not as bad as boiling the oceans. Still, it’s not a decisive argument. The big other questions are the costs of power storage and of more extensive transmission networks — since when the sun isn’t shining and the wind isn’t blowing in one place, they probably are somewhere else. (I agree with Will that using the price mechanism to force electricity usage to conform to supply from renewables is definitely the wrong answer.) The CT debate doesn’t answer those questions. But it’s still an example of how informative blog debate can be when there are people both sides with real expertise who are prepared to engage seriously with each other.

On other blogs, other wonders. Here is a fascinating post by Laura Tanenbaum on the end of sex-segregated job ads and the false dichotomy between “elite” and “grassroots” feminism.

This very interesting article by Jose Azar on the extent and economic significance of common ownership of corporate shares deserves a post of its own.

Here’s a nice little think piece from Bloomberg wondering what, if anything, is meant by “the natural rate” of interest. I’m glad to see some skepticism about this concept in the larger conversation. In my mind, the “natural rate” is one of the key patches covering over the disconnect between economic theory and the observable economy.

Bhenn Bhiorach has a funny post on the lengths people will go to to claim that low inflation is really high inflation.

CBO Forecasts: What’s Under the Hood?

In this post I want to say something about the methodology behind the CBO’s potential output forecasts. Here’s the tl;dr:

Officially, the CBO forecasts are based on a production function, which requires use of a number of unobservable parameters and questionable assumptions. But with one important exception, use of the the production function has no effect on the final estimate of potential output. The results are always very close to what you would get by simply extrapolating the trend of labor productivity.

The post is based on various CBO documents on their forecasting methodology, mainly this one, this one and this one, and on the relevant sections of the most recent Budget and Economic Outlook. It’s also much too long, mainly negative critique, and basically unnecessary to the larger argument I’m developing. Much of the post is devoted to the neoclassical production function (a serious demerit); since I’m far from an expert on it, there’s a nontrivial chance of embarrassing mistakes. You can keep reading or not.

Continue reading CBO Forecasts: What’s Under the Hood?

Links for July 20, 2016

The responsibilities of heterodoxy. Arjun Jayadev and I have an ongoing project of interviewing dissenting economists who we think deserve wider recognition. Our first interview was with Axel Leijonhufvud; the second, just now up at the INET site, is with our old professor Jim Crotty. Jim’s ECO 710 was for us, as for hundreds of UMass grad students over the past 30 years, the starting point for systematically thinking about the economy as a whole. (You could think of him as sort of the Earth-II version of Rudi Dornbusch.) You can read more of my thoughts about him at the link.

Here’s an interesting clip that didn’t make it into the INET version:

The radicalism — and coherence — of Keynes larger political-economic program is a topic I’d like to return to in the future, as is the importance of an organic relationship to some broader social movement or political project. For heterodox economists, I think even more than for other academics, it’s impossible to even do good scholarship if your relationship to your object of study is only as a scholar. Science, as Max Weber says, “presupposes that what is yielded by scientific work is important in the sense that it is ‘worth being known.’ … This presupposition cannot be proved by scientific means.”

The problem with heterodoxy. The post here about the non-existence of mainstream economics is now up at Evonomics, in a somewhat improved form. While we’re on that topic, I will let loose with a peeve. Joan Robinson is like a god to me — in an anthropological sense she might even literally be a divinity for my tribe. But I hate that often-quoted line that the only reason to study economics is “to avoid being fooled by economists.” It reinforces the worst habit of heterodox people: putting negative critique above positive efforts to understand the world.

Articles to read. Three recent articles that really deserve posts of their own:

Thomas Palley on negative interest rates (he’s against them).

Jerry Epstein on the costs of big finance.

Cédric Durand and Maxime Gueuder on the weakening link between profits and corporate investment. I’ve been planning to write something on exactly this; clearly it will have to respond to this paper.

Interest rates and trade imbalances. Izabella Kaminska has a very interesting post up at FT Alphaville. (Does she write any other kind?) This one brings out two important points. First, to the extent that low interest rates mainly lead to bringing forward future spending — this is probably especially true in housing — they are good tools for dealing with temporary downturns but not for secular shortfalls. (Kaminska doesn’t say so, but this is one reason the “natural rate” concept is misleading.) Second, the macroeconomic significance of trade imbalances depends on what happens to the corresponding financial flows — and this isn’t automatic. Continuous British surpluses in the gold standard era were compatible with steady growth of the world economy because they financed investment — in railroads especially — in the peripheral countries, using British capital goods. The general lesson is:

If countries want to carry international surpluses indefinitely the suggestion here is they need also to reinvest those “savings” into capacity expanding investments abroad.

Also in FT Alphaville, here’s a nice post by Matthew Klein on a question that should be obvious, but is seldom asked: If large current account deficits are dangerous, then what exactly is the purpose of allowing free flows of portfolio investment across borders? From the point of view of the receiving country, the only benefit of portfolio inflows is that it lets them finance current account deficits. If that’s not desirable, why allow them? Klein doesn’t give the clear negative answer that I would, but it’s the right question to be asking.

Evicted. At Dissent, my Roosevelt colleague Mike Konczal has an excellent review of two new books on eviction and foreclosure. It’s an important topic, and Evicted looks like an important book. I had some debates about it on twitter that clarified a question that doesn’t quite come out in the review itself. Are housing costs so high for more people because of market and regulatory failures that allow landlords to exploit poor tenants? Or is the cost of providing adequate housing simply greater than poor families can pay? The first points toward tenants organizing and better regulation of rental housing, the latter toward direct or indirect subsidies or direct public provision of housing.

Also from Mike, a review of two recent books about the appropriate role of the state.

Rising health costs in Europe. Via Adam Gaffney, here’s an interesting article on rising household payments for heatlh care in Europe, even in countries that are notionally single payer. Adam’s summary:

It supports the hypothesis—put forward by many—that there has been a *partial* retreat from universal health care in Europe (especially if we define universal health care as free care at point of use for all). The main findings are as follows:

-The odds of having any out-of-pocket expenditures on health care in the previous 12 months (among 11 European nations) were 2.6 fold higher in 2013 than in 2006-2007;

-Overall out of pocket payments for health care increased 43.6% (inflation adjusted) between 2006-2007 and 2013;

-The proportion of individuals with catastrophic health care expenditures rose, particularly in Spain and Italy, which have been particularly hard-struck by austerity.

My take: We need to stop thinking about universal health care as an end goal or terminus: its actually a work in progress, and neoliberal health policy ideology has already done a number on it in Europe.

The poor stay poor. My old UMass comrade Mike Carr has a new article on income mobility, coauthored with Emily Wiemers. There’s a nice writeup of it in The Atlantic.

The right vs the rentiers? I was interested to learn that one of Theresa May’s declared priorities as Prime Minister is reforming corporate governance, including requiring worker representatives on boards. I have no idea if anything will come of it, but it’s interesting to see ideas that would be well to the left of the mainstream here adopted at least rhetorically by a conservative government in the UK. Was also interesting, in the coverage, to see some acknowledgement of the importance of cogovernance and works councils in Germany. Obviously export surpluses should not be taken as the measure of economic success in any broader sense, but it’s still worth pointing out that Europe’s biggest exporter is one of its least liberal economies.

Also in Theresa May news, doesn’t it seem like if Article 50 can’t be invoked without Scotland’s ok, that means Brexit isn’t happening? Which I think was the safe bet all along. Because if what scares you is that the “burghers of middle England” can “with a single vote destroy trillions of dollars of value,” then you can probably relax. The trillions will win the next round.

Trend, Forecast and Actual: Decomposing the Differences

Second post in a series. Post one is here.

The previous post argued that if we want to know how much of the slowdown in US growth is a result of the Great Recession, a reasonable starting point is to look at revisions to estimates of potential GDP since the recession. As it turns out, while CBO forecasts prior to the recession did predict slower growth than the long-run trend, the predicted slowdown was only about a quarter what we’ve actually seen. That suggests that most of the output shortfall relative to trend is due to the collapse in demand following the financial crisis, rather than to slower growth in the economy’s productive capacity.

The next natural step is to separate slower growth into various components and see how they behave individually. There are various ways to do this, but perhaps the most straightforward is the identity:

output = productivity * employment = productivity * laborforce * (1 – unemployment)

The big advantage of this is that we are working with fairly directly observable aggregates. Another advantage, important for present purposes, is that the CBO gives the relevant components for its estimates of potential output. Productivity here means labor productivity — output per worker. As applied to potential, unemployment means the non-accelerating inflation rate of unemployment, or NAIRU — the unemployment rate supposed to be consistent with stable inflation, which is targeted by the central bank.

So, here are the CBO’s forecasts of the three components over the past 10 years. The format is the same as the figure for output in the previous post: The horizontal axis is the year being forecasted, and the different lines represent forecasts made in various years — the blue-green ones before the start of the recession, the orange-red ones after it. (The forecasts are published in January, so the 2009 one is the first to incorporate data from the recession.) The heavy black lines show the actual historical behavior of the variable.

In the following graph, the forceast lines are for the NAIRU, the black line is for the actual unemployment rate.

We see some interesting things here. With respect to productivity, there are modest downward adjustments in 2007 and 2008 but the big adjustment come later, especially in 2009 and 2014. And the later adjustments are not just to the level of productivity but to the trend. Not only is there no convergence between actual productivity and pre-recession forecasts, the gap has continued to get wider over time. For laborforce, by contrast, the biggest adjustments come before the recession, especially in 2003, when the trend is revised downward. The post-recession revisions are smaller. The actual trajectory of the laborforce does show a definite reversion toward the immediate pre-recession forecasts. Finally, the estimated NAIRU was adjusted upward during the recession and back down since then with no systematic movement one way or the other. So the fairly stable gap between post-recession output and the pre-recession trend is a bit misleading. It combines two opposite developments, a widening productivity gap and a narrowing laborforce gap.

These results are summarized in the following table. The first column shows the difference between actual 2016 output and what you would predict by projecting forward the 1990-2006 trend. [1] The second column shows the deviation from trend that was already predicted in the CBO’s 2006 forecasts for 2016. The third column shows the revisions made since 2006.

	Actual vs Trend	Predicted vs Trend	Post-Recession Revision
Output	-14.1	-4.2	-10.4
Productivity	-5.4	5.1	-8.7
Laborforce	-9.2	-8.9	-1.8
Unemployment	-0.3	-0.4	0.1

What do we see here? Again, if we look at the shortfall of GDP relative to the pre-2006 trend, about 30 percent was predicted by the CBO. But the picture is quite different for employment and productivity taken separately. The deceleration in laborforce growth (which is about one-third slower population growth, two-thirds declining laborforce participation) was almost entirely predicted by the CBO. But in 2006 the CBO was also predicting above-trend productivity growth, which would have largely offset slower growth of the laborforce. The downward revisions over the past decade have mainly been to productivity — 9 percent, versus only a 2 percent downward revision to potential laborforce. Unemployment does not play an important role in either case — both actual unemployment and the estimated NAIRU are very close to their 2006 values. (This is different from Europe, where higher NAIRUs explain a large part of the change in potential output.)

Now this is a bit of a puzzle. I mentioned in the previous post a couple articles on hysteresis; I also very much like this piece by Laurence Ball. But all of them discuss hysteresis primarily in terms of the laborforce — the long-term unemployed giving up on job search and so on. That doesn’t mesh well with the fact that the downward revisions in potential output reflect mainly slower productivity growth rather than slower laborforce growth.

One natural way to interpret this is that (as Claudia Sahm suggests on twitter) the downward revisions in potential output since 2007 simply reflect a correction to earlier overestimates to productivity growth, which perhaps gave too much weight to a one-time acceleration in the 1990s. I ‘ll return in a later post to why I don’t accept this. For now, let’s just say that we take seriously the Summers-Ball view that downward revisions to potential output since the recession are a measure of hysteresis. Then we have to broaden our understanding of what hysteresis means. We can’t think of it as mainly a labor-market phenomenon.

In the next post, I’ll discuss a couple remaining points on the CBO forecasts. Then, a post arguing that the simultaneous deceleration of employment, productivity and prices looks more like an extended business-cycle downturn than a decline in the economy’s productive capacity. Then we’ll look at demographics and laborforce participation. And then back to the question of productivity, which I’d like to link to Joan Robinson’s concept of disguised unemployment.

[1] I use the years 1990 and 2006 because those are two years where actual output is very close to the CBO estimate of potential.

What Do Changing Estimates of Potential Output Tell Us?

I want to revisit the question we were debating last spring, about the space for additional expansionary policy in the US. How far is the economy from potential, in whatever relevant sense? This post will be the first in a series, and there will be a paper sometime in the fall.

One way to approach the question is to ask another one: How much of the shortfall in output relative to the pre-2008 trend is the result of the recession, as opposed to “structural” factors that would have led to slower growth in any case? The two questions are somewhat independent: Even if demographic factors, let’s say, were tending to reduce laborforce growth, there’s no reason in principle that couldn’t be overcome by stronger demand. On the other hand, even if we reject the idea that the recession itself resulted from a decline in productive capacity, it’s possible that a persistent demand shortfall could over time damage capacity in a way that can’t subsequently be repaired by restoring demand. Still, an output shortfall that is due to the collapse in spending in 2008-2009 is more likely to be reversed by increased spending, than one that is due to other causes.

Laurence Ball, DeLong and Summers, and Fatas and Summers, among others, try to answer the question of how much the decline in output is due to the recession, by comparing pre-recession estimates of potential output with more recent ones. A change in potential output attributable to changes in current output is often referred to as “hysteresis.” Changing forecasts are a reasonable measure of hysteresis: If predictable that structural factors like the changing age mix of the population were going to lead to slower growth, then it should in fact have been predicted; so systematic deviations from the forecasts must reflect something else. Now, if you are committed to the view that demand effects are strictly short-run, then a persistent deviation from trend necessarily reflects supply-side developments of some kind. But as long as we have no strong priors either way, the evolution of estimated potential over time should be informative about how much of the output shortfall is the result of the recession and how much is due to other causes.

The three papers do different versions of this exercise and all find that (1) the bulk of the slowdown in growth since 2008 is due to the recession, or at least was not predicted prior to it; and (2) there is no tendency for output to return to potential, rather, changes in current output are fully passed through to later estimates of potential. Here’s a simple version. The figure shows the CBO’s 10-year forecasts of potential GDP from 2002 through this year, along with historical GDP. (All are in 2009 dollars.)

The horizontal axis shows the year the estimate is for. The different lines show estimates made in different years. So the purple line at the top is the ten-year forecast of potential output published in January 2002, while the pink line at the bottom is the ten-year forecast published in January of this year. What do we see?

First, there has been a systematic reduction in estimates of potential. While there are some upward adjustment in the early years, more recently all the adjustments have been downward. The estimates of 2015, for example, first made in 2005, has been reduced every year since then. Same goes for 2016 and all future years. These are not random errors. And they are not small: the estimate of 2016 potential GDP made by the CBO in 2016 was more than 10 percent greater than the estimate this year.

Second, there is no tendency for output to return to earlier estimates of potential. While the official output gap has gotten much smaller since 2009, this is entirely a result of the downward adjustment of potential; there has been no closing of the gap between output and potential estimated in 2009 or earlier years.

On the other hand, these revisions can’t be all due to the recession, since the CBO significantly reduced its forecasts of potential output growth over 2005-2007. The largest revision comes in 2009, after the first year of recession. (Again, these are January forecasts.) But there had already been significant downward adjustments at that point. (Especially, as we’ll see in the net post, in predicted laborforce growth.) Still, most of the deviation from trend reflects post-recession adjustments in potential.

It breaks down like this. Current GDP is 12 percent below what you would have predicted based on long-run growth rates up to 2008. The CBO puts the current output gap at around 2 percent. This reflects the fact that the CBO currently considers full employment to be 4.8 percent unemployment, slightly below the current level. The remainder of the 12-point gap represents a slowdown in potential output growth. How much of that was predicted in 2005? Less than none – at that time, the CBO’s forecast for 2015 output was 1.5 percent above the long run trend. By January 2008 — the last pre-recession forecast — the CBO had revised its 2015 forecast down by about 4 percent, to 3 percent below trend. In 2009, after the first year of the recession, it revised it down another 3 points, to 6 percent below trend. And over the past seven years it’s been revised down seven more times for a total of 5 points, to reach the current estimate of potential of around 10 percent below trend. So about a quarter of the 12 point gap between current GDP and its long-run trend was predicted before the recession.

Now the fact that the slowdown was not predicted before the recession, doesn’t prove that it is due to the recession. It does, I think, allow us to reject things like “aging of the baby boomers” as the main explanation for the shortfall: Something that easily predictable, would have been predicted. (And as we’ll see in a later post, demographic changes cannot in fact explain the slowdown in output growth— the effect of aging on labor force participation, while real, is too small to explain the actual decline, and it’s offset by a comparable but less-discussed shift in the other direction — the declining share of households with young children.) It is, however, possible that some new development (a “shock” in the jargon, but I don’t like this term) just happened to reduce the economy’s productive capacity at the same time it was recovering from the recession.

In their 2012 article, DeLong and Summers argue that the absence of wage and price growth is strong evidence against this latter explanation:

It is possible that these revisions reflect not … hysteresis but merely the recognition that previous forecasts of potential output were too high. However, an elementary signal extraction point rebuts this interpretation. … one should not reduce one’s estimate of potential output if lower-than-previously-expected levels of production are associated with lower-than-previously-expected levels of inflation. … Typically, the bad news that leads to a marking down of potential output is not news that output is lower than, but rather news that output and inflation together are above, their anticipated co-movement line. Such news is not in evidence.

Over the past four years inflation has only fallen further, so the point presumably still holds.

So if we take the unpredicted decline in potential as a measure of the effects of the recession, we’re left with something like this: Of the gap between actual US GDP and its pre-2008 trend, 75 percent is due to the continuing effects of the recession, 25 percent to other factors. That seems like a reasonable place to start.

I Don’t See Any Method At All

I’ve felt for a while that most critiques of economics miss the mark. They start from the premise that economics is a systematic effort to understand the concrete social phenomena we call “the economy,” an effort that has gone wrong in some way.

I don’t think that’s the right way to think about it. I think McCloskey was right to say that economics is just what economists do. Economic theory is essentially closed formal system; it’s a historical accident that there is some overlap between its technical vocabulary and the language used to describe concrete economic phenomena. Economics the discipline is to the economy the sphere of social reality as chess theory is to medieval history: The statement, say, that “queens are most effective when supported by strong bishops” might be reasonable in both domains, but studying its application in the one case will not help at all in applying it in in the other. A few years ago Richard Posner said that he used to think economics meant the study of “rational” behavior in whatever domain, but after the financial crisis he decided it should mean the study of the behavior of the economy using whatever methodologies. (I can’t find the exact quote.) Descriptively, he was right the first time; but the point is, these are two different activities. Or to steal a line from my friend Suresh, the best way to think about what most economists do is as a kind of constrained-maximization poetry. Makes no more sense to ask “is it true” than of a haiku.

One consequence of this is, as I say, that radical criticism of the realism or logical consistency of orthodox economics do nothing to get us closer to a positive understanding of the economy. How is a raven unlike a writing desk? An endless number of ways, and enumerating them will leave you no wiser about either corvids or carpentry. Another consequence, the topic of the remainder of this post, is that when we turn to concrete economic questions there isn’t really a “mainstream” at all. Left critics want to take academic orthodoxy, a right-wing political vision, and the economic policy preferred by the established authorities, and roll them into a coherent package. But I don’t think you can. I think there is a mix of common-sense opinions, political prejudices, conventional business practice, and pragmatic rules of thumb, supported in an ad hoc, opportunistic way by bits and pieces of economic theory. It’s not possible to deduce the whole tottering pile from a few foundational texts.

More concretely: An economics education trains you to think in terms of real exchange — in terms of agents who (somehow or other) have come into possession of a bundle of goods, which they trade with each other. You can only use this framework to make statements about real economic phenomena if they are understood in terms of the supply side — if economic outcomes are understood in terms of different endowments of goods, or different real uses for them. Unless you’re in a position to self-consciously take another perspective, fitting your understanding of economic phenomena into a broader framework is going to mean expressing it as this kind of story, about the limited supply of real resources available, and the unlimited demands on them to meet real human needs. But there may be no sensible story of that kind to tell.

More concretely: What are the major macroeconomic developments of the past ten to twenty years, compared, say, with the previous fifty? For the US and most other developed countries, the list might look like:

– low and falling inflation

– low and falling interest rates

– slower growth of output

– slower growth of employment

– low business investment

– slower growth of labor productivity growth

– a declining share of wages in income

If you pick up an economics textbook and try to apply it to the world around you, these are some of the main phenomena you’d want to explain. What does the orthodox, supply-side theory tell us?

The textbook says that lower inflation is normally the result of a positive supply shock — an increase in real resources or an improvement in technology. OK. But then what do we make of the slowdown in output and productivity?

The textbook says that, over the long run interest rates must reflect the marginal product of capital — the central bank (and monetary factors in general) can only change interest rates in the short run, not over a decade or more. In the Walrasian world, the interest rate and the return on investment are the same thing. So a sustained decline in interest rates must mean a decline in the marginal product of capital.

OK. So in combination with the slowdown in output growth, that suggests a negative technological shock. But that should mean higher inflation. Didn’t we just say that lower inflation implies a positive technological shock?

Employment growth in this framework is normally determined by demographics, or perhaps by structural changes in labor markets that change the effective labor supply. Slower employment growth means a falling labor supply — but that should, again, be inflationary. And it should be associated with higher wagess: If labor is becoming relatively scarce, its price should rise. Yes, the textbook combines a bargaining mode of wage determination for the short run with a marginal product story for the long run, without ever explaining how they hook up, but in this case it doesn’t matter, the two stories agree. A fall in the labor supply will result in a rise in the marginal product of labor as it’s withdrawn from the least productive activities — that’s what “marginal” means! So either way the demographic story of falling employment is inconsistent with low inflation, with a falling wage share, and with the showdown in productivity growth.

Slower growth of labor productivity could be explained by an increase in labor supply — but then why has employment decelerated so sharply? More often it’s taken as technologically determined. Slower productivity growth then implies a slowdown in innovation — which at least is consistent with low interest rates and low investment. But this “negative technology shock” should again, be inflationary. And it should be associated with a fall in the return to capital, not a rise.

On the other hand, the decline in the labor share is supposed to reflect a change in productive technology that encourages substitution of capital for labor, robots and all that. But how is this reconciled with the fall in interest rates, in investment and in labor productivity? To replace workers with robots, someone has to make the robots, and someone has to buy them. And by definition this raises the productivity of the remaining workers.

Which subset of these mutually incompatible stories does the “mainstream” actually believe? I don’t know that they consistently believe any of them. My impression is that people adopt one or another based on the question at hand, while avoiding any systematic analysis through violent abuse of the ceteris paribus condition.

To paraphrase Leijonhufvud, on Mondays and Wednesdays wages are low because technological progress has slowed down, holding down labor productivity. On Tuesdays and Thursdays wages are low because technological progress has sped up, substituting capital for labor. Students may come away a bit confused but the main takeaway is clear: Low wages are the result of inexorable, exogenous technological change, and not of any kind of political choice. And certainly not of weak aggregate demand.

Larry Summers in this actually quite good Washington Post piece, at least is no longer talking about robots. But he can’t completely resist the supply-side lure: “The situation is worse in other countries with more structural issues and slower labor-force growth.” Wait, why would they be worse? As he himself says, “our problem today is insufficient inflation,” so what’s needed “is to convince people that prices will rise at target rates in the future,” which will “require … very tight markets.” If that’s true, then restrictions on labor supply are a good thing — they make it easier to generate wage and price increases. But that is still an unthought.

I admit, Summers does go on to say:

In the presence of chronic excess supply, structural reform has the risk of spurring disinflation rather than contributing to a necessary increase in inflation. There is, in fact, a case for strengthening entitlement benefits so as to promote current demand. The key point is that the traditional OECD-type recommendations cannot be right as both a response to inflationary pressures and deflationary pressures. They were more right historically than they are today.

That’s progress, for sure — “less right” is a step toward “completely wrong”. The next step will be to say what his argument logically requires. If the problem is as he describes it then structural “problems” are part of the solution.