Archive for the 'temporary equilibrium' Category

Hicks on IS-LM and Temporary Equilibrium

Jan, commenting on my recent post about Krugman, Minsky and IS-LM, quoted the penultimate paragraph of J. R. Hicks’s 1980 paper on IS-LM in the Journal of Post-Keynesian Economics, a brand of economics not particularly sympathetic to Hicks’s invention. Hicks explained that in the mid-1930s he had been thinking along lines similar to Keynes’s even before the General Theory was published, and had the basic idea of IS-LM in his mind even before he had read the General Theory, while also acknowledging that his enthusiasm for the IS-LM construct had waned considerably over the years.

Hicks discussed both the similarities and the differences between his model and IS-LM. But as the discussion proceeds, it becomes clear that what he is thinking of as his model is what became his model of temporary equilibrium in Value and Capital. So it really is important to understand what Hicks felt were the similarities as well as the key differences between the temporary- equilibrium model, and the IS-LM model. Here is how Hicks put it:

I recognized immediately, as soon as I read The General Theory, that my model and Keynes’ had some things in common. Both of us fixed our attention on the behavior of an economy during a period—a period that had a past, which nothing that was done during the period could alter, and a future, which during the period was unknown. Expectations of the future would nevertheless affect what happened during the period. Neither of us made any assumption about “rational expectations” ; expectations, in our models, were strictly exogenous.3 (Keynes made much more fuss over that than I did, but there is the same implication in my model also.) Subject to these data— the given equipment carried over from the past, the production possibilities within the period, the preference schedules, and the given expectations— the actual performance of the economy within the period was supposed to be determined, or determinable. It would be determined as an equilibrium performance, with respect to these data.

There was all this in common between my model and Keynes'; it was enough to make me recognize, as soon as I saw The General Theory, that his model was a relation of mine and, as such, one which I could warmly welcome. There were, however, two differences, on which (as we shall see) much depends. The more obvious difference was that mine was a flexprice model, a perfect competition model, in which all prices were flexible, while in Keynes’ the level of money wages (at least) was exogenously determined. So Keynes’ was a model that was consistent with unemployment, while mine, in his terms, was a full employment model. I shall have much to say about this difference, but I may as well note, at the start, that I do not think it matters much. I did not think, even in 1936, that it mattered much. IS-LM was in fact a translation of Keynes’ nonflexprice model into my terms. It seemed to me already that that could be done; but how it is done requires explanation.

The other difference is more fundamental; it concerns the length of the period. Keynes’ (he said) was a “short-period,” a term with connotations derived from Marshall; we shall not go far wrong if we think of it as a year. Mine was an “ultra-short-period” ; I called it a week. Much more can happen in a year than in a week; Keynes has to allow for quite a lot of things to happen. I wanted to avoid so much happening, so that my (flexprice) markets could reflect propensities (and expectations) as they are at a moment. So it was that I made my markets open only on a Monday; what actually happened during the ensuing week was not to affect them. This was a very artificial device, not (I would think now) much to be recommended. But the point of it was to exclude the things which might happen, and must disturb the markets, during a period of finite length; and this, as we shall see, is a very real trouble in Keynes. (pp. 139-40)

Hicks then explained how the specific idea of the IS-LM model came to him as a result of working on a three-good Walrasian system in which the solution could be described in terms of equilibrium in two markets, the third market necessarily being in equilibrium if the other two were in equilibrium. That’s an interesting historical tidbit, but the point that I want to discuss is what I think is Hicks’s failure to fully understand the significance of his own model, whose importance, regrettably, he consistently underestimated in later work (e.g., in Capital and Growth and in this paper).

The point that I want to focus on is in the second paragraph quoted above where Hicks says “mine [i.e. temporary equilibrium] was a flexprice model, a perfect competition model, in which all prices were flexible, while in Keynes’ the level of money wages (at least) was exogenously determined. So Keynes’ was a model that was consistent with unemployment, while mine, in his terms, was a full employment model.” This, it seems to me, is all wrong, because Hicks, is taking a very naïve and misguided view of what perfect competition and flexible prices mean. Those terms are often mistakenly assumed to meant that if prices are simply allowed to adjust freely, all  markets will clear and all resources will be utilized.

I think that is a total misconception, and the significance of the temporary-equilibrium construct is in helping us understand why an economy can operate sub-optimally with idle resources even when there is perfect competition and markets “clear.” What prevents optimality and allows resources to remain idle despite freely adjustming prices and perfect competition is that the expectations held by agents are not consistent. If expectations are not consistent, the plans based on those expectations are not consistent. If plans are not consistent, then how can one expect resources to be used optimally or even at all? Thus, for Hicks to assert, casually without explicit qualification, that his temporary-equilibrium model was a full-employment model, indicates to me that Hicks was unaware of the deeper significance of his own model.

If we take a full equilibrium as our benchmark, and look at how one of the markets in that full equilibrium clears, we can imagine the equilibrium as the intersection of a supply curve and a demand curve, whose positions in the standard price/quantity space depend on the price expectations of suppliers and of demanders. Different, i.e, inconsistent, price expectations would imply shifts in both the demand and supply curves from those corresponding to full intertemporal equilibrium. Overall, the price expectations consistent with a full intertemporal equilibrium will in some sense maximize total output and employment, so when price expectations are inconsistent with full intertemporal equilibrium, the shifts of the demand and supply curves will be such that they will intersect at points corresponding to less output and less employment than would have been the case in full intertemporal equilibrium. In fact, it is possible to imagine that expectations on the supply side and the demand side are so inconsistent that the point of intersection between the demand and supply curves corresponds to an output (and hence employment) that is way less than it would have been in full intertemporal equilibrium. The problem is not that the price in the market doesn’t allow the market to clear. Rather, given the positions of the demand and supply curves, their point of intersection implies a low output, because inconsistent price expectations are such that potentially advantageous trading opportunities are not being recognized.

So for Hicks to assert that his flexprice temporary-equilibrium model was (in Keynes’s terms) a full-employment model without noting the possibility of a significant contraction of output (and employment) in a perfectly competitive flexprice temporary-equilibrium model when there are significant inconsistencies in expectations suggests strongly that Hicks somehow did not fully comprehend what his own creation was all about. His failure to comprehend his own model also explains why he felt the need to abandon the flexprice temporary-equilibrium model in his later work for a fixprice model.

There is, of course, a lot more to be said about all this, and Hicks’s comments concerning the choice of a length of the period are also of interest, but the clear (or so it seems to me) misunderstanding by Hicks of what is entailed by a flexprice temporary equilibrium is an important point to recognize in evaluating both Hicks’s work and his commentary on that work and its relation to Keynes.

Temporary Equilibrium One More Time

It’s always nice to be noticed, especially by Paul Krugman. So I am not upset, but in his response to my previous post, I don’t think that Krugman quite understood what I was trying to convey. I will try to be clearer this time. It will be easiest if I just quote from his post and insert my comments or explanations.

Glasner is right to say that the Hicksian IS-LM analysis comes most directly not out of Keynes but out of Hicks’s own Value and Capital, which introduced the concept of “temporary equilibrium”.

Actually, that’s not what I was trying to say. I wasn’t making any explicit connection between Hicks’s temporary-equilibrium concept from Value and Capital and the IS-LM model that he introduced two years earlier in his paper on Keynes and the Classics. Of course that doesn’t mean that the temporary equilibrium method isn’t connected to the IS-LM model; one would need to do a more in-depth study than I have done of Hicks’s intellectual development to determine how much IS-LM was influenced by Hicks’s interest in intertemporal equilibrium and in the method of temporary equilibrium as a way of analyzing intertemporal issues.

This involves using quasi-static methods to analyze a dynamic economy, not because you don’t realize that it’s dynamic, but simply as a tool. In particular, V&C discussed at some length a temporary equilibrium in a three-sector economy, with goods, bonds, and money; that’s essentially full-employment IS-LM, which becomes the 1937 version with some price stickiness. I wrote about that a long time ago.

Now I do think that it’s fair to say that the IS-LM model was very much in the spirit of Value and Capital, in which Hicks deployed an explicit general-equilibrium model to analyze an economy at a Keynesian level of aggregation: goods, bonds, and money. But the temporary-equilibrium aspect of Value and Capital went beyond the Keynesian analysis, because the temporary equilibrium analysis was explicitly intertemporal, all agents formulating plans based on explicit future price expectations, and the inconsistency between expected prices and actual prices was explicitly noted, while in the General Theory, and in IS-LM, price expectations were kept in the background, making an appearance only in the discussion of the marginal efficiency of capital.

So is IS-LM really Keynesian? I think yes — there is a lot of temporary equilibrium in The General Theory, even if there’s other stuff too. As I wrote in the last post, one key thing that distinguished TGT from earlier business cycle theorizing was precisely that it stopped trying to tell a dynamic story — no more periods, forced saving, boom and bust, instead a focus on how economies can stay depressed. Anyway, does it matter? The real question is whether the method of temporary equilibrium is useful.

That is precisely where I think Krugman’s grasp on the concept of temporary equilibrium is slipping. Temporary equilibrium is indeed about periods, and it is explicitly dynamic. In my previous post I referred to Hicks’s discussion in Capital and Growth, about 25 years after writing Value and Capital, in which he wrote

The Temporary Equilibrium model of Value and Capital, also, is “quasi-static” [like the Keynes theory] – in just the same sense. The reason why I was contented with such a model was because I had my eyes fixed on Keynes.

As I read this passage now — and it really bothered me when I read it as I was writing my previous post — I realize that what Hicks was saying was that his desire to conform to the Keynesian paradigm led him to compromise the integrity of the temporary equilibrium model, by forcing it to be “quasi-static” when it really was essentially dynamic. The challenge has been to convert a “quasi-static” IS-LM model into something closer to the temporary-equilibrium method that Hicks introduced, but did not fully execute in Value and Capital.

What are the alternatives? One — which took over much of macro — is to do intertemporal equilibrium all the way, with consumers making lifetime consumption plans, prices set with the future rationally expected, and so on. That’s DSGE — and I think Glasner and I agree that this hasn’t worked out too well. In fact, economists who never learned temporary-equiibrium-style modeling have had a strong tendency to reinvent pre-Keynesian fallacies (cough-Say’s Law-cough), because they don’t know how to think out of the forever-equilibrium straitjacket.

Yes, I agree! Rational expectations, full-equilibrium models have turned out to be a regression, not an advance. But the way I would make the point is that the temporary-equilibrium method provides a sort of a middle way to do intertemporal dynamics without presuming that consumption plans and investment plans are always optimal.

What about disequilibrium dynamics all the way? Basically, I have never seen anyone pull this off. Like the forever-equilibrium types, constant-disequilibrium theorists have a remarkable tendency to make elementary conceptual mistakes.

Again, I agree. We can’t work without some sort of equilibrium conditions, but temporary equilibrium provides a way to keep the discipline of equilibrium without assuming (nearly) full optimality.

Still, Glasner says that temporary equilibrium must involve disappointed expectations, and fails to take account of the dynamics that must result as expectations are revised.

Perhaps I was unclear, but I thought I was saying just the opposite. It’s the “quasi-static” IS-LM model, not temporary equilibrium, that fails to take account of the dynamics produced by revised expectations.

I guess I’d say two things. First, I’m not sure that this is always true. Hicks did indeed assume static expectations — the future will be like the present; but in Keynes’s vision of an economy stuck in sustained depression, such static expectations will be more or less right.

Again, I agree. There may be self-fulfilling expectations of a low-income, low-employment equilibrium. But I don’t think that that is the only explanation for such a situation, and certainly not for the downturn that can lead to such an equilibrium.

Second, those of us who use temporary equilibrium often do think in terms of dynamics as expectations adjust. In fact, you could say that the textbook story of how the short-run aggregate supply curve adjusts over time, eventually restoring full employment, is just that kind of thing. It’s not a great story, but it is the kind of dynamics Glasner wants — and it’s Econ 101 stuff.

Again, I agree. It’s not a great story, but, like it or not, the story is not a Keynesian story.

So where does this leave us? I’m not sure, but my impression is that Krugman, in his admiration for the IS-LM model, is trying too hard to identify IS-LM with the temporary-equilibrium approach, which I think represented a major conceptual advance over both the Keynesian model and the IS-LM representation of the Keynesian model. Temporary equilibrium and IS-LM are not necessarily inconsistent, but I mainly wanted to point out that the two aren’t the same, and shouldn’t be conflated.

Krugman on Minsky, IS-LM and Temporary Equilibrium

Catching up on my blog reading, I found this one from Paul Krugman from almost two weeks ago defending the IS-LM model against Hyman Minsky’s criticism (channeled by his student Lars Syll) that IS-LM misrepresented the message of Keynes’s General Theory. That is an old debate, and it’s a debate that will never be resolved because IS-LM is a nice way of incorporating monetary effects into the pure income-expenditure model that was the basis of Keynes’s multiplier analysis and his policy prescriptions. On the other hand, the model leaves out much of what most interesting and insightful in the General Theory – precisely the stuff that could not easily be distilled into a simple analytic model.

Here’s Krugman:

Lars Syll approvingly quotes Hyman Minsky denouncing IS-LM analysis as an “obfuscation” of Keynes; Brad DeLong disagrees. As you might guess, so do I.

There are really two questions here. The less important is whether something like IS-LM — a static, equilibrium analysis of output and employment that takes expectations and financial conditions as given — does violence to the spirit of Keynes. Why isn’t this all that important? Because Keynes was a smart guy, not a prophet. The General Theory is interesting and inspiring, but not holy writ.

It’s also a protean work that contains a lot of different ideas, not necessarily consistent with each other. Still, when I read Minsky putting into Keynes’s mouth the claim that

Only a theory that was explicitly cyclical and overtly financial was capable of being useful

I have to wonder whether he really read the book! As I read the General Theory — and I’ve read it carefully — one of Keynes’s central insights was precisely that you wanted to step back from thinking about the business cycle. Previous thinkers had focused all their energy on trying to explain booms and busts; Keynes argued that the real thing that needed explanation was the way the economy seemed to spend prolonged periods in a state of underemployment:

[I]t is an outstanding characteristic of the economic system in which we live that, whilst it is subject to severe fluctuations in respect of output and employment, it is not violently unstable. Indeed it seems capable of remaining in a chronic condition of subnormal activity for a considerable period without any marked tendency either towards recovery or towards complete collapse.

So Keynes started with a, yes, equilibrium model of a depressed economy. He then went on to offer thoughts about how changes in animal spirits could alter this equilibrium; but he waited until Chapter 22 (!) to sketch out a story about the business cycle, and made it clear that this was not the centerpiece of his theory. Yes, I know that he later wrote an article claiming that it was all about the instability of expectations, but the book is what changed economics, and that’s not what it says.

This all seems pretty sensible to me. Nevertheless, there is so much in the General Theory — both good and bad – that isn’t reflected in IS-LM, that to reduce the General Theory to IS-LM is a kind of misrepresentation. And to be fair, Hicks himself acknowledged that IS-LM was merely a way of representing one critical difference in the assumptions underlying the Keynesian and the “Classical” analyses of macroeconomic equilibrium.

But I would take issue with the following assertion by Krugman.

The point is that Keynes very much made use of the method of temporary equilibrium — interpreting the state of the economy in the short run as if it were a static equilibrium with a lot of stuff taken provisionally as given — as a way to clarify thought. And the larger point is that he was right to do this.

When people like me use something like IS-LM, we’re not imagining that the IS curve is fixed in position for ever after. It’s a ceteris paribus thing, just like supply and demand. Assuming short-run equilibrium in some things — in this case interest rates and output — doesn’t mean that you’ve forgotten that things change, it’s just a way to clarify your thought. And the truth is that people who try to think in terms of everything being dynamic all at once almost always end up either confused or engaging in a lot of implicit theorizing they don’t even realize they’re doing.

When I think of a temporary equilibrium, the most important – indeed the defining — characteristic of that temporary equilibrium is that expectations of at least some agents have been disappointed. The disappointment of expectations is likely to, but does not strictly require, a revision of disappointed expectations and of the plans conditioned on those expectations. The revision of expectations and plans as a result of expectations being disappointed is what gives rise to a dynamic adjustment process. But that is precisely what is excluded from – or at least not explicitly taken into account by – the IS-LM model. There is nothing in the IS-LM model that provides any direct insight into the process by which expectations are revised as a result of being disappointed. That Keynes could so easily think in terms of a depressed economy being in equilibrium suggests to me that he was missing what I regard as the key insight of the temporary-equilibrium method.

Of course, there are those who argue, perhaps most notably Roger Farmer, that economies have multiple equilibria, each with different levels of output and employment corresponding to different expectational parameters. That seems to me a more Keynesian approach, an approach recognizing that expectations can be self-fulfilling, than the temporary-equilibrium approach in which the focus is on mistaken and conflicting expectations, not their self-fulfillment.

Now to be fair, I have to admit that Hicks, himself, who introduced the temporary-equilibrium approach in Value and Capital (1939) later (1965) suggested in Capital and Growth (p. 65) that both the Keynes in the General Theory and the temporary-equilibrium approach of Value and Capital were “quasi-static.” The analysis of the General Theory “is not the analysis of a process; no means has been provided by which we can pass from one Keynesian period to the next. . . . The Temporary Equilibrium model of Value and Capital, also, is quasi-static in just the same sense. The reason why I was contented with such a model was because I had my eyes fixed on Keynes.

Despite Hicks’s identification of the temporary-equilibrium method with Keynes’s method in the General Theory, I think that Hicks was overly modest in assessing his own contribution in Value and Capital, failing to appreciate the full significance of the method he had introduced. Which, I suppose, just goes to show that you can’t assume that the person who invents a concept or an idea is necessarily the one who has the best, or most comprehensive, understanding of what the concept means of what its significance is.

Paul Krugman and Roger Farmer on Sticky Wages

I was pleasantly surprised last Friday to see that Paul Krugman took favorable notice of my post about sticky wages, but also registering some disagreement.

[Glasner] is partially right in suggesting that there has been a bit of a role reversal regarding the role of sticky wages in recessions: Keynes asserted that wage flexibility would not help, but Keynes’s self-proclaimed heirs ended up putting downward nominal wage rigidity at the core of their analysis. By the way, this didn’t start with the New Keynesians; way back in the 1940s Franco Modigliani had already taught us to think that everything depended on M/w, the ratio of the money supply to the wage rate.

That said, wage stickiness plays a bigger role in The General Theory — and in modern discussions that are consistent with what Keynes said — than Glasner indicates.

To document his assertion about Keynes, Krugman quotes a passage from the General Theory in which Keynes seems to suggest that in the nineteenth century inflexible wages were partially compensated for by price level movements. One might quibble with Krugman’s interpretation, but the payoff doesn’t seem worth the effort.

But I will quibble with the next paragraph in Krugman’s post.

But there’s another point: even if you don’t think wage flexibility would help in our current situation (and like Keynes, I think it wouldn’t), Keynesians still need a sticky-wage story to make the facts consistent with involuntary unemployment. For if wages were flexible, an excess supply of labor should be reflected in ever-falling wages. If you want to say that we have lots of willing workers unable to find jobs — as opposed to moochers not really seeking work because they’re cradled in Paul Ryan’s hammock — you have to have a story about why wages aren’t falling.

Not that I really disagree with Krugman that the behavior of wages since the 2008 downturn is consistent with some stickiness in wages. Nevertheless, it is still not necessarily the case that, if wages were flexible, an excess supply of labor would lead to ever-falling wages. In a search model of unemployment, if workers are expecting wages to rise every year at a 3% rate, and instead wages rise at only a 1% rate, the model predicts that unemployment will rise, and will continue to rise (or at least not return to the natural rate) as long as observed wages did not increase as fast as workers were expecting wages to rise. Presumably over time, wage expectations would adjust to a new lower rate of increase, but there is no guarantee that the transition would be speedy.

Krugman concludes:

So sticky wages are an important part of both old and new Keynesian analysis, not because wage cuts would help us, but simply to make sense of what we see.

My own view is actually a bit more guarded. I think that “sticky wages” is simply a name that we apply to a problematic phenomenon for ehich we still haven’t found a really satisfactory explanation for. Search models, for all their theoretical elegance, simply can’t explain the observed process by which unemployment rises during recessions, i.e., by layoffs and a lack of job openings rather than an increase in quits and refused offers, as search models imply. The suggestion in my earlier post was intended to offer a possible basis of understanding what the phrase “sticky wages” is actually describing.

Roger Farmer, a long-time and renowned UCLA economist, also commented on my post on his new blog. Welcome to the blogosphere, Roger.

Roger has a different take on the sticky-wage phenomenon. Roger argues, as did some of the commenters to my post, that wages are not sticky. To document this assertion, Roger presents a diagram showing that the decline of nominal wages closely tracked that of prices for the first six years of the Great Depression. From this evidence Roger concludes that nominal wage rigidity is not the cause of rising unemployment during the Great Depression, and presumably, not the cause of rising unemployment in the Little Depression.

farmer_sticky_wagesInstead, Roger argues, the rise in unemployment was caused by an outbreak of self-fulfilling pessimism. Roger believes that there are many alternative equilibria and which equilibrium (actually equilibrium time path) we reach depends on what our expectations are. Roger also believes that our expectations are rational, so that we get what we expect, as he succinctly phrases it “beliefs are fundamental.” I have a lot of sympathy for this way of looking at the economy. In fact one of the early posts on this blog was entitled “Expectations are Fundamental.” But as I have explained in other posts, I am not so sure that expectations are rational in any useful sense, because I think that individual expectations diverge. I don’t think that there is a single way of looking at reality. If there are many potential equilibria, why should everyone expect the same equilibrium. I can be an optimist, and you can be a pessimist. If we agreed, we would be right, but if we disagree, we will both be wrong. What economic mechanism is there to reconcile our expectations? In a world in which expectations diverge — a world of temporary equilibrium — there can be cumulative output reductions that get propagated across the economy as each sector fails to produce its maximum potential output, thereby reducing the demand for the output of other sectors to which it is linked. That’s what happens when there is trading at prices that don’t correspond to the full optimum equilibrium solution.

So I agree with Roger in part, but I think that the coordination problem is (at least potentially) more serious than he imagines.

Big Ideas in Macroeconomics: A Review

Steve Williamson recently plugged a new book by Kartik Athreya (Big Ideas in Macroeconomics), an economist at the Federal Reserve Bank of Richmond, which tries to explain in relatively non-technical terms what modern macroeconomics is all about. I will acknowledge that my graduate training in macroeconomics predated the rise of modern macro, and I am not fluent in the language of modern macro, though I am trying to fill in the gaps. And this book is a good place to start. I found Athreya’s book a good overview of the field, explaining the fundamental ideas and how they fit together.

Big Ideas in Macroeconomics is a moderately big book, 415 pages, covering a very wide range of topics. It is noteworthy, I think, that despite its size, there is so little overlap between the topics covered in this book, and those covered in more traditional, perhaps old-fashioned, books on macroeconomics. The index contains not a single entry on the price level, inflation, deflation, money, interest, total output, employment or unemployment. Which is not to say that none of those concepts are ever mentioned or discussed, just that they are not treated, as they are in traditional macroeconomics books, as the principal objects of macroeconomic inquiry. The conduct of monetary or fiscal policy to achieve some explicit macroeconomic objective is never discussed. In contrast, there are repeated references to Walrasian equilibrium, the Arrow-Debreu-McKenzie model, the Radner model, Nash-equilibria, Pareto optimality, the first and second Welfare theorems. It’s a new world.

The first two chapters present a fairly detailed description of the idea of Walrasian general equilibrium and its modern incarnation in the canonical Arrow-Debreu-McKenzie (ADM) model.The ADM model describes an economy of utility-maximizing households and profit-maximizing firms engaged in the production and consumption of commodities through time and space. There are markets for commodities dated by time period, specified by location and classified by foreseeable contingent states of the world, so that the same physical commodity corresponds to many separate commodities, each corresponding to different time periods and locations and to contingent states of the world. Prices for such physically identical commodities are not necessarily uniform across times, locations or contingent states.The demand for road salt to de-ice roads depends on whether conditions, which depend on time and location and on states of the world. For each different possible weather contingency, there would be a distinct market for road salt for each location and time period.

The ADM model is solved once for all time periods and all states of the world. Under appropriate conditions, there is one (and possibly more than one) intertemporal equilibrium, all trades being executed in advance, with all deliveries subsequently being carried out, as time an contingencies unfold, in accordance with the terms of the original contracts.

Given the existence of an equilibrium, i.e., a set of prices subject to which all agents are individually optimizing, and all markets are clearing, there are two classical welfare theorems stating that any such equilibrium involves a Pareto-optimal allocation and any Pareto-optimal allocation could be supported by an equilibrium set of prices corresponding to a suitably chosen set of initial endowments. For these optimality results to obtain, it is necessary that markets be complete in the sense that there is a market for each commodity in each time period and contingent state of the world. Without a complete set of markets in this sense, the Pareto-optimality of the Walrasian equilibrium cannot be proved.

Readers may wonder about the process by which an equilibrium price vector would actually be found through some trading process. Athreya invokes the fiction of a Walrasian clearinghouse in which all agents (truthfully) register their notional demands and supplies at alternative price vectors. Based on these responses the clearinghouse is able to determine, by a process of trial and error, the equilibrium price vector. Since the Walrasian clearinghouse presumes that no trading occurs except at an equilibrium price vector, there can be no assurance that an equilibrium price vector would ever be arrived at under an actual trading process in which trading occurs at disequilibrium prices. Moreover, as Clower and Leijonhufvud showed over 40 years ago (“Say’s Principle: What it Means and What it Doesn’t Mean”), trading at disequilibrium prices may cause cumulative contractions of aggregate demand because the total volume of trade at a disequilibrium price will always be less than the volume of trade at an equilibrium price, the volume of trade being constrained by the lesser of quantity supplied and quantity demanded.

In the view of modern macroeconomics, then, Walrasian general equilibrium, as characterized by the ADM model, is the basic and overarching paradigm of macroeconomic analysis. To be sure, modern macroeconomics tries to go beyond the highly restrictive assumptions of the ADM model, but it is not clear whether the concessions made by modern macroeconomics to the real world go very far in enhancing the realism of the basic model.

Chapter 3, contains some interesting reflections on the importance of efficiency (Pareto-optimality) as a policy objective and on the trade-offs between efficiency and equity and between ex-ante and ex-post efficiency. But these topics are on the periphery of macroeconomics, so I will offer no comment here.

In chapter 4, Athreya turns to some common criticisms of modern macroeconomics: that it is too highly aggregated, too wedded to the rationality assumption, too focused on equilibrium steady states, and too highly mathematical. Athreya correctly points out that older macroeconomic models were also highly aggregated, so that if aggregation is a problem it is not unique to modern macroeconomics. That’s a fair point, but skirts some thorny issues. As Athreya acknowledges in chapter 5, an important issue separating certain older macroeconomic traditions (both Keynesian and Austrian among others) is the idea that macroeconomic dysfunction is a manifestation of coordination failure. It is a property – a remarkable property – of Walrasian general equilibrium that it achieves perfect (i.e., Pareto-optimal) coordination of disparate, self-interested, competitive individual agents, fully reconciling their plans in a way that might have been achieved by an omniscient and benevolent central planner. Walrasian general equilibrium fully solves the coordination problem. Insofar as important results of modern macroeconomics depend on the assumption that a real-life economy can be realistically characterized as a Walrasian equilibrium, modern macroeconomics is assuming that coordination failures are irrelevant to macroeconomics. It is only after coordination failures have been excluded from the purview of macroeconomics that it became legitimate (for the sake of mathematical tractability) to deploy representative-agent models in macroeconomics, a coordination failure being tantamount, in the context of a representative agent model, to a form of irrationality on the part of the representative agent. Athreya characterizes choices about the level of aggregation as a trade-off between realism and tractability, but it seems to me that, rather than making a trade-off between realism and tractability, modern macroeconomics has simply made an a priori decision that coordination problems are not a relevant macroeconomic concern.

A similar argument applies to Athreya’s defense of rational expectations and the use of equilibrium in modern macroeconomic models. I would not deny that there are good reasons to adopt rational expectations and full equilibrium in some modeling situations, depending on the problem that theorist is trying to address. The question is whether it can be appropriate to deviate from the assumption of a full rational-expectations equilibrium for the purposes of modeling fluctuations over the course of a business cycle, especially a deep cyclical downturn. In particular, the idea of a Hicksian temporary equilibrium in which agents hold divergent expectations about future prices, but markets clear period by period given those divergent expectations, seems to offer (as in, e.g., Thompson’s “Reformulation of Macroeconomic Theory“) more realism and richer empirical content than modern macromodels of rational expectations.

Athreya offers the following explanation and defense of rational expectations:

[Rational expectations] purports to explain the expectations people actually have about the relevant items in their own futures. It does so by asking that their expectations lead to economy-wide outcomes that do not contradict their views. By imposing the requirement that expectations not be systematically contradicted by outcomes, economists keep an unobservable object from becoming a source of “free parameters” through which we can cheaply claim to have “explained” some phenomenon. In other words, in rational-expectations models, expectations are part of what is solved for, and so they are not left to the discretion of the modeler to impose willy-nilly. In so doing, the assumption of rational expectations protects the public from economists.

This defense of rational expectations plainly belies betrays the methodological arrogance of modern macroeconomics. I am all in favor of solving a model for equilibrium expectations, but solving for equilibrium expectations is certainly not the same as insisting that the only interesting or relevant result of a model is the one generated by the assumption of full equilibrium under rational expectations. (Again see Thompson’s “Reformulation of Macroeconomic Theory” as well as the classic paper by Foley and Sidrauski, and this post by Rajiv Sethi on his blog.) It may be relevant and useful to look at a model and examine its properties in a state in which agents hold inconsistent expectations about future prices; the temporary equilibrium existing at a point in time does not correspond to a steady state. Why is such an equilibrium uninteresting and uninformative about what happens in a business cycle? But evidently modern macroeconomists such as Athreya consider it their duty to ban such models from polite discourse — certainly from the leading economics journals — lest the public be tainted by economists who might otherwise dare to abuse their models by making illicit assumptions about expectations formation and equilibrium concepts.

Chapter 5 is the most important chapter of the book. It is in this chapter that Athreya examines in more detail the kinds of adjustments that modern macroeconomists make in the Walrasian/ADM paradigm to accommodate the incompleteness of markets and the imperfections of expectation formation that limit the empirical relevance of the full ADM model as a macroeconomic paradigm. To do so, Athreya starts by explaining how the Radner model in which a less than the full complement of Arrow-Debreu contingent-laims markets is available. In the Radner model, unlike the ADM model, trading takes place through time for those markets that actually exist, so that the full Walrasian equilibrium exists only if agents are able to form correct expectations about future prices. And even if the full Walrasian equilibrium exists, in the absence of a complete set of Arrow-Debreu markets, the classical welfare theorems may not obtain.

To Athreya, these limitations on the Radner version of the Walrasian model seem manageable. After all, if no one really knows how to improve on the equilibrium of the Radner model, the potential existence of Pareto improvements to the Radner equilibrium is not necessarily that big a deal. Athreya expands on the discussion of the Radner model by introducing the neoclassical growth model in both its deterministic and stochastic versions, all the elements of the dynamic stochastic general equilibrium (DSGE) model that characterizes modern macroeconomics now being in place. Athreya closes out the chapter with additional discussions of the role of further modifications to the basic Walrasian paradigm, particularly search models and overlapping-generations models.

I found the discussion in chapter 5 highly informative and useful, but it doesn’t seem to me that Athreya faces up to the limitations of the Radner model or to the implied disconnect between the Walraisan paradigm and macroeconomic analysis. A full Walrasian equilibrium exists in the Radner model only if all agents correctly anticipate future prices. If they don’t correctly anticipate future prices, then we are in the world of Hicksian temporary equilibrium. But in that world, the kind of coordination failures that Athreya so casually dismisses seem all too likely to occur. In a world of temporary equilibrium, there is no guarantee that intertemporal budget constraints will be effective, because those budget constraint reflect expected, not actual, future prices, and, in temporary equilibrium, expected prices are not the same for all transactors. Budget constraints are not binding in a world in which trading takes place through time based on possibly incorrect expectations of future prices. Not only does this mean that all the standard equilibrium and optimality conditions of Walrasian theory are violated, but that defaults on IOUs and, thus, financial-market breakdowns, are entirely possible.

In a key passage in chapter 5, Athreya dismisses coordination-failure explanations, invidiously characterized as Keynesian, for inefficient declines in output and employment. While acknowledging that such fluctuations could, in theory, be caused by “self-fulfilling pessimism or fear,” Athreya invokes the benchmark Radner trading arrangement of the ADM model. “In the Radner economy, Athreya writes, “households and firms have correct expectations for the spot market prices one period hence.” The justification for that expectational assumption, which seems indistinguishable from the assumption of a full, rational-expectations equilibrium, is left unstated. Athreya continues:

Granting that they indeed have such expectations, we can now ask about the extent to which, in a modern economy, we can have outcomes that are extremely sensitive to them. In particular, is it the case that under fairly plausible conditions, “optimism” and “pessimism” can be self-fulfilling in ways that make everyone (or nearly everyone) better off in the former than the latter?

Athreya argues that this is possible only if the aggregate production function of the economy is characterized by increasing returns to scale, so that productivity increases as output rises.

[W]hat I have in mind is that the structure of the economy must be such that when, for example, all households suddenly defer consumption spending (and save instead), interest rates do not adjust rapidly to forestall such a fall in spending by encouraging firms to invest.

Notice that Athreya makes no distinction between a reduction in consumption in which people shift into long-term real or financial assets and one in which people shift into holding cash. The two cases are hardly identical, but Athreya has nothing to say about the demand for money and its role in macroeconomics.

If they did, under what I will later describe as a “standard” production side for the economy, wages would, barring any countervailing forces, promptly rise (as the capital stock rises and makes workers more productive). In turn, output would not fall in response to pessimism.

What Athreya is saying is that if we assume that there is a reduction in the time preference of households, causing them to defer present consumption in order to increase their future consumption, the shift in time preference should be reflected in a rise in asset prices, causing an increase in the production of durable assets, and leading to an increase in wages insofar as the increase in the stock of fixed capital implies an increase in the marginal product of labor. Thus, if all the consequences of increased thrift are foreseen at the moment that current demand for output falls, there would be a smooth transition from the previous steady state corresponding to a high rate of time preference to the new steady state corresponding to a low rate of time preference.

Fine. If you assume that the economy always remains in full equilibrium, even in the transition from one steady state to another, because everyone has rational expectations, you will avoid a lot of unpleasantness. But what if entrepreneurial expectations do not change instantaneously, and the reduction in current demand for output corresponding to reduced spending on consumption causes entrepreneurs to reduce, not increase, their demand for capital equipment? If, after the shift in time preference, total spending actually falls, there may be a chain of disappointments in expectations, and a series of defaults on IOUs, culminating in a financial crisis. Pessimism may indeed be self-fulfilling. But Athreya has a just-so story to tell, and he seems satisfied that there is no other story to be told. Others may not be so easily satisfied, especially when his just-so story depends on a) the rational expectations assumption that many smart people have a hard time accepting as even remotely plausible, and b) the assumption that no trading takes place at disequilibrium prices. Athreya continues:

Thus, at least within the context of models in which households and firms are not routinely incorrect about the future, multiple self-fulfilling outcomes require particular features of the production side of the economy to prevail.

Actually what Athreya should have said is: “within the context of models in which households and firms always predict future prices correctly.”

In chapter 6, Athreya discusses how modern macroeconomics can and has contributed to the understanding of the financial crisis of 2007-08 and the subsequent downturn and anemic recovery. There is a lot of very useful information and discussion of various issues, especially in connection with banking and financial markets. But further comment at this point would be largely repetitive.

Anyway, despite my obvious and strong disagreements with much of what I read, I learned a lot from Athreya’s well-written and stimulating book, and I actually enjoyed reading it.

What Kind of Equilibrium Is This?

In my previous post, I suggested that Stephen Williamson’s views about the incapacity of monetary policy to reduce unemployment, and his fears that monetary expansion would simply lead to higher inflation and a repeat of the bad old days the 1970s when inflation and unemployment spun out of control, follow from a theoretical presumption that the US economy is now operating (as it almost always does) in the neighborhood of equilibrium. This does not seem right to me, but it is the sort of deep theoretical assumption (e.g., like the rationality of economic agents) that is not subject to direct empirical testing. It is part of what the philosopher Imre Lakatos called the hard core of a (in this case Williamson’s) scientific research program. Whatever happens, Williamson will process the observed facts in terms of a theoretical paradigm in which prices adjust and markets clear. No other way of viewing reality makes sense, because Williamson cannot make any sense of it in terms of the theoretical paradigm or world view to which he is committed. I actually have some sympathy with that way of looking at the world, but not because I think it’s really true; it’s just the best paradigm we have at the moment. But I don’t want to follow that line of thought too far now, but who knows, maybe another time.

A good illustration of how Williamson understands his paradigm was provided by blogger J. P. Koning in his comment on my previous post copying the following quotation from a post written by Williamson a couple of years on his blog.

In other cases, as in the link you mention, there are people concerned about disequilibrium phenomena. These approaches are or were popular in Europe – I looked up Benassy and he is still hard at work. However, most of the mainstream – and here I’m including New Keynesians – sticks to equilibrium economics. New Keynesian models may have some stuck prices and wages, but those models don’t have to depart much from standard competitive equilibrium (or, if you like, competitive equilibrium with monopolistic competition). In those models, you have to determine what a firm with a stuck price produces, and that is where the big leap is. However, in terms of determining everything mathematically, it’s not a big deal. Equilibrium economics is hard enough as it is, without having to deal with the lack of discipline associated with “disequilibrium.” In equilibrium economics, particularly monetary equilibrium economics, we have all the equilibria (and more) we can handle, thanks.

I actually agree that departing from the assumption of equilibrium can involve a lack of discipline. Market clearing is a very powerful analytical tool, and to give it up without replacing it with an equally powerful analytical tool leaves us theoretically impoverished. But Williamson seems to suggest (or at least leaves ambiguous) that there is only one kind of equilibrium that can be handled theoretically, namely a fully optimal general equilibrium with perfect foresight (i.e., rational expectations) or at least with a learning process leading toward rational expectations. But there are other equilibrium concepts that preserve market clearing, but without imposing, what seems to me, the unreasonable condition of rational expectations and (near) optimality.

In particular, there is the Hicksian concept of a temporary equilibrium (inspired by Hayek’s discussion of intertemporal equilibrium) which allows for inconsistent expectations by economic agents, but assumes market clearing based on supply and demand schedules reflecting those inconsistent expectations. Nearly 40 years ago, Earl Thompson was able to deploy that equilibrium concept to derive a sub-optimal temporary equilibrium with Keynesian unemployment and a role for countercyclical monetary policy in minimizing inefficient unemployment. I have summarized and discussed Thompson’s model previously in some previous posts (here, here, here, and here), and I hope to do a few more in the future. The model is hardly the last word, but it might at least serve as a starting point for thinking seriously about the possibility that not every state of the economy is an optimal equilibrium state, but without abandoning market clearing as an analytical tool.


About Me

David Glasner
Washington, DC

I am an economist at the Federal Trade Commission. Nothing that you read on this blog necessarily reflects the views of the FTC or the individual commissioners. Although I work at the FTC as an antitrust economist, most of my research and writing has been on monetary economics and policy and the history of monetary theory. In my book Free Banking and Monetary Reform, I argued for a non-Monetarist non-Keynesian approach to monetary policy, based on a theory of a competitive supply of money. Over the years, I have become increasingly impressed by the similarities between my approach and that of R. G. Hawtrey and hope to bring Hawtrey's unduly neglected contributions to the attention of a wider audience.

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