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Graeber Against Economics

David Graeber’s vitriolic essay “Against Economics” in the New York Review of Books has generated responses from Noah Smith and Scott Sumner among others. I don’t disagree with much that Noah or Scott have to say, but I want to dig a little deeper than they did into some of Graeber’s arguments, because even though I think he is badly misinformed on many if not most of the subjects he writes about, I actually have some sympathy for his dissatisfaction with the current state of economics. Graeber wastes no time on pleasantries.

There is a growing feeling, among those who have the responsibility of managing large economies, that the discipline of economics is no longer fit for purpose. It is beginning to look like a science designed to solve problems that no longer exist.

A serious polemicist should avoid blatant mischaracterizations, exaggerations and cheap shots, and should be well-grounded in the object of his critique, thereby avoiding criticisms that undermine his own claims to expertise. I grant that  Graeber has some valid criticisms to make, even agreeing with him, at least in part, on some of them. But his indiscriminate attacks on, and caricatures of, all neoclassical economics betrays a superficial understanding of that discipline.

Graeber begins by attacking what he considers the misguided and obsessive focus on inflation by economists.

A good example is the obsession with inflation. Economists still teach their students that the primary economic role of government—many would insist, its only really proper economic role—is to guarantee price stability. We must be constantly vigilant over the dangers of inflation. For governments to simply print money is therefore inherently sinful.

Every currency unit, or banknote issued by a central bank, now in circulation, as Graeber must know, has been “printed.” So to say that economists consider it sinful for governments to print money is either a deliberate falsehood, or an emotional rhetorical outburst, as Graeber immediately, and apparently unwittingly, acknowledges!

If, however, inflation is kept at bay through the coordinated action of government and central bankers, the market should find its “natural rate of unemployment,” and investors, taking advantage of clear price signals, should be able to ensure healthy growth. These assumptions came with the monetarism of the 1980s, the idea that government should restrict itself to managing the money supply, and by the 1990s had come to be accepted as such elementary common sense that pretty much all political debate had to set out from a ritual acknowledgment of the perils of government spending. This continues to be the case, despite the fact that, since the 2008 recession, central banks have been printing money frantically [my emphasis] in an attempt to create inflation and compel the rich to do something useful with their money, and have been largely unsuccessful in both endeavors.

Graeber’s use of the ambiguous pronoun “this” beginning the last sentence of the paragraph betrays his own confusion about what he is saying. Central banks are printing money and attempting to “create” inflation while supposedly still believing that inflation is a menace and printing money is a sin. Go figure.

We now live in a different economic universe than we did before the crash. Falling unemployment no longer drives up wages. Printing money does not cause inflation. Yet the language of public debate, and the wisdom conveyed in economic textbooks, remain almost entirely unchanged.

Again showing an inadequate understanding of basic economic theory, Graeber suggests that, in theory if not practice, falling unemployment should cause wages to rise. The Philips Curve, upon which Graeber’s suggestion relies, represents the empirically observed negative correlation between the rate of average wage increase and the rate of unemployment. But correlation does not imply causation, so there is no basis in economic theory to assert that falling unemployment causes the rate of increase in wages to accelerate. That the empirical correlation between unemployment and wage increases has not recently been in evidence provides no compelling reason for changing textbook theory.

From this largely unfounded and attack on economic theory – a theory which I myself consider, in many respects, inadequate and unreliable – Graeber launches a bitter diatribe against the supposed hegemony of economists over policy-making.

Mainstream economists nowadays might not be particularly good at predicting financial crashes, facilitating general prosperity, or coming up with models for preventing climate change, but when it comes to establishing themselves in positions of intellectual authority, unaffected by such failings, their success is unparalleled. One would have to look at the history of religions to find anything like it.

The ability to predict financial crises would be desirable, but that cannot be the sole criterion for whether economics has advanced our understanding of how economic activity is organized or what effects policy changes have. (I note parenthetically that many economists defensively reject the notion that economic crises are predictable on the grounds that if economists could predict a future economic crisis, those predictions would be immediately self-fulfilling. This response, of course, effectively disproves the idea that economists could predict that an economic crisis would occur in the way that astronomers predict solar eclipses. But this response slays a strawman. The issue is not whether economists can predict future crises, but whether they can identify conditions indicating an increased likelihood of a crisis and suggest precautionary measures to reduce the likelihood that a potential crisis will occur. But Graeber seems uninterested in or incapable of engaging the question at even this moderate level of subtlety.)

In general, I doubt that economists can make more than a modest contribution to improved policy-making, and the best that one can hope for is probably that they steer us away from the worst potential decisions rather than identifying the best ones. But no one, as far as I know, has yet been burned at the stake by a tribunal of economists.

To this day, economics continues to be taught not as a story of arguments—not, like any other social science, as a welter of often warring theoretical perspectives—but rather as something more like physics, the gradual realization of universal, unimpeachable mathematical truths. “Heterodox” theories of economics do, of course, exist (institutionalist, Marxist, feminist, “Austrian,” post-Keynesian…), but their exponents have been almost completely locked out of what are considered “serious” departments, and even outright rebellions by economics students (from the post-autistic economics movement in France to post-crash economics in Britain) have largely failed to force them into the core curriculum.

I am now happy to register agreement with something that Graeber says. Economists in general have become overly attached to axiomatic and formalistic mathematical models that create a false and misleading impression of rigor and mathematical certainty. In saying this, I don’t dispute that mathematical modeling is an important part of much economic theorizing, but it should not exclude other approaches to economic analysis and discourse.

As a result, heterodox economists continue to be treated as just a step or two away from crackpots, despite the fact that they often have a much better record of predicting real-world economic events. What’s more, the basic psychological assumptions on which mainstream (neoclassical) economics is based—though they have long since been disproved by actual psychologists—have colonized the rest of the academy, and have had a profound impact on popular understandings of the world.

That heterodox economists have a better record of predicting economic events than mainstream economists is an assertion for which Graeber offers no evidence or examples. I would not be surprised if he could cite examples, but one would have to weigh the evidence surrounding those examples before concluding that predictions by heterodox economists were more accurate than those of their mainstream counterparts.

Graeber returns to the topic of monetary theory, which seems a particular bugaboo of his. Taking the extreme liberty of holding up Mrs. Theresa May as a spokesperson for orthodox economics, he focuses on her definitive 2017 statement that there is no magic money tree.

The truly extraordinary thing about May’s phrase is that it isn’t true. There are plenty of magic money trees in Britain, as there are in any developed economy. They are called “banks.” Since modern money is simply credit, banks can and do create money literally out of nothing, simply by making loans. Almost all of the money circulating in Britain at the moment is bank-created in this way.

What Graeber chooses to ignore is that banks do not operate magically; they make loans and create deposits in seeking to earn profits; their decisions are not magical, but are oriented toward making profits. Whether they make good or bad decisions is debatable, but the debate isn’t about a magical process; it’s a debate about theory and evidence. Graeber describe how he thinks that economists think about how banks create money, correctly observing that there is a debate about how that process works, but without understanding those differences or their significance.

Economists, for obvious reasons, can’t be completely oblivious to the role of banks, but they have spent much of the twentieth century arguing about what actually happens when someone applies for a loan. One school insists that banks transfer existing funds from their reserves, another that they produce new money, but only on the basis of a multiplier effect). . . Only a minority—mostly heterodox economists, post-Keynesians, and modern money theorists—uphold what is called the “credit creation theory of banking”: that bankers simply wave a magic wand and make the money appear, secure in the confidence that even if they hand a client a credit for $1 million, ultimately the recipient will put it back in the bank again, so that, across the system as a whole, credits and debts will cancel out. Rather than loans being based in deposits, in this view, deposits themselves were the result of loans.

The one thing it never seemed to occur to anyone to do was to get a job at a bank, and find out what actually happens when someone asks to borrow money. In 2014 a German economist named Richard Werner did exactly that, and discovered that, in fact, loan officers do not check their existing funds, reserves, or anything else. They simply create money out of thin air, or, as he preferred to put it, “fairy dust.”

Graeber is right that economists differ in how they understand banking. But the simple transfer-of-funds view, a product of the eighteenth century, was gradually rejected over the course of the nineteenth century; the money-multiplier view largely superseded it, enjoying a half-century or more of dominance as a theory of banking, still remains a popular way for introductory textbooks to explain how banking works, though it would be better if it were decently buried and forgotten. But since James Tobin’s classic essay “Commercial banks as creators of money” was published in 1963, most economists who have thought carefully about banking have concluded that the amount of deposits created by banks corresponds to the quantity of deposits that the public, given their expectations about the future course of the economy and the future course of prices, chooses to hold. The important point is that while a bank can create deposits without incurring more than the negligible cost of making a book-keeping, or an electronic, entry in a customer’s account, the creation of a deposit is typically associated with a demand by the bank to hold either reserves in its account with the Fed or to hold some amount of Treasury instruments convertible, on very short notice, into reserves at the Fed.

Graeber seems to think that there is something fundamental at stake for the whole of macroeconomics in the question whether deposits created loans or loans create deposits. I agree that it’s an important question, but not as significant as Graeber believes. But aside from that nuance, what’s remarkable is that Graeber actually acknowledges that the weight of professional opinion is on the side that says that loans create deposits. He thus triumphantly cites a report by Bank of England economists that correctly explained that banks create money and do so in the normal course of business by making loans.

Before long, the Bank of England . . . rolled out an elaborate official report called “Money Creation in the Modern Economy,” replete with videos and animations, making the same point: existing economics textbooks, and particularly the reigning monetarist orthodoxy, are wrong. The heterodox economists are right. Private banks create money. Central banks like the Bank of England create money as well, but monetarists are entirely wrong to insist that their proper function is to control the money supply.

Graeber, I regret to say, is simply exposing the inadequacy of his knowledge of the history of economics. Adam Smith in The Wealth of Nations explained that banks create money who, in doing so, saved the resources that would have been wasted on creating additional gold and silver. Subsequent economists from David Ricardo through Henry Thornton, J. S. Mill and R. G. Hawtrey were perfectly aware that banks can supply money — either banknotes or deposits — at less than the cost of mining and minting new coins, as they extend their credit in making loans to borrowers. So what is at issue, Graeber to the contrary notwithstanding, is not a dispute between orthodoxy and heterodoxy.

In fact, central banks do not in any sense control the money supply; their main function is to set the interest rate—to determine how much private banks can charge for the money they create.

Central banks set a rental price for reserves, thereby controlling the quantity of reserves into which bank deposits are convertible that is available to the economy. One way to think about that quantity is that the quantity of reserves along with the aggregate demand to hold reserves determines the exchange value of reserves and hence the price level; another way to think about it is that the interest rate or the implied policy stance of the central bank helps to determine the expectations of the public about the future course of the price level which is what determines – within some margin of error or range – what the future course of the price level will turn out to be.

Almost all public debate on these subjects is therefore based on false premises. For example, if what the Bank of England was saying were true, government borrowing didn’t divert funds from the private sector; it created entirely new money that had not existed before.

This is just silly. Funds may or may not be diverted from the private sector, but the total available resources to society is finite. If the central bank creates additional money, it creates additional claims to those resources and the creation of additional claims to resources necessarily has an effect on the prices of inputs and of outputs.

One might have imagined that such an admission would create something of a splash, and in certain restricted circles, it did. Central banks in Norway, Switzerland, and Germany quickly put out similar papers. Back in the UK, the immediate media response was simply silence. The Bank of England report has never, to my knowledge, been so much as mentioned on the BBC or any other TV news outlet. Newspaper columnists continued to write as if monetarism was self-evidently correct. Politicians continued to be grilled about where they would find the cash for social programs. It was as if a kind of entente cordiale had been established, in which the technocrats would be allowed to live in one theoretical universe, while politicians and news commentators would continue to exist in an entirely different one.

Even if we stipulate that this characterization of what the BBC and newspaper columnists believe is correct, what we would have — at best — is a commentary on the ability of economists to communicate their understanding of how the economy works to the intelligentsia that communicates to ordinary citizens. It is not in and of itself a commentary on the state of economic knowledge, inasmuch as Graeber himself concedes that most economists don’t accept monetarism. And that has been the case, as Noah Smith pointed out in his Bloomberg column on Graeber, since the early 1980s when the Monetarist experiment in trying to conduct monetary policy by controlling the monetary aggregates proved entirely unworkable and had to be abandoned as it was on the verge of precipitating a financial crisis.

Only after this long warmup decrying the sorry state of contemporary economic theory does Graeber begin discussing the book under review Money and Government by Robert Skidelsky.

What [Skidelsky] reveals is an endless war between two broad theoretical perspectives. . . The crux of the argument always seems to turn on the nature of money. Is money best conceived of as a physical commodity, a precious substance used to facilitate exchange, or is it better to see money primarily as a credit, a bookkeeping method or circulating IOU—in any case, a social arrangement? This is an argument that has been going on in some form for thousands of years. What we call “money” is always a mixture of both, and, as I myself noted in Debt (2011), the center of gravity between the two tends to shift back and forth over time. . . .One important theoretical innovation that these new bullion-based theories of money allowed was, as Skidelsky notes, what has come to be called the quantity theory of money (usually referred to in textbooks—since economists take endless delight in abbreviations—as QTM).

But these two perspectives are not mutually exclusive, and, depending on time, place, circumstances, and the particular problem that is the focus of attention, either of the two may be the appropriate paradigm for analysis.

The QTM argument was first put forward by a French lawyer named Jean Bodin, during a debate over the cause of the sharp, destablizing price inflation that immediately followed the Iberian conquest of the Americas. Bodin argued that the inflation was a simple matter of supply and demand: the enormous influx of gold and silver from the Spanish colonies was cheapening the value of money in Europe. The basic principle would no doubt have seemed a matter of common sense to anyone with experience of commerce at the time, but it turns out to have been based on a series of false assumptions. For one thing, most of the gold and silver extracted from Mexico and Peru did not end up in Europe at all, and certainly wasn’t coined into money. Most of it was transported directly to China and India (to buy spices, silks, calicoes, and other “oriental luxuries”), and insofar as it had inflationary effects back home, it was on the basis of speculative bonds of one sort or another. This almost always turns out to be true when QTM is applied: it seems self-evident, but only if you leave most of the critical factors out.

In the case of the sixteenth-century price inflation, for instance, once one takes account of credit, hoarding, and speculation—not to mention increased rates of economic activity, investment in new technology, and wage levels (which, in turn, have a lot to do with the relative power of workers and employers, creditors and debtors)—it becomes impossible to say for certain which is the deciding factor: whether the money supply drives prices, or prices drive the money supply.

As a matter of logic, if the value of money depends on the precious metals (gold or silver) from which coins were minted, the value of money is necessarily affected by a change in the value of the metals used to coin money. Because a large increase in the stock of gold and silver, as Graeber concedes, must reduce the value of those metals, subsequent inflation then being attributable, at least in part, to the gold and silver discoveries even if the newly mined gold and silver was shipped mainly to privately held Indian and Chinese hoards rather than minted into new coins. An exogenous increase in prices may well have caused the quantity of credit money to increase, but that is analytically distinct from the inflationary effect of a reduced value of gold or silver when, as was the case in the sixteenth century, money is legally defined as a specific weight of gold or silver.

Technically, this comes down to a choice between what are called exogenous and endogenous theories of money. Should money be treated as an outside factor, like all those Spanish dubloons supposedly sweeping into Antwerp, Dublin, and Genoa in the days of Philip II, or should it be imagined primarily as a product of economic activity itself, mined, minted, and put into circulation, or more often, created as credit instruments such as loans, in order to meet a demand—which would, of course, mean that the roots of inflation lie elsewhere?

There is no such choice, because any theory must posit certain initial conditions and definitions, which are given or exogenous to the analysis. How the theory is framed and which variables are treated as exogenous and which are treated as endogenous is a matter of judgment in light of the problem and the circumstances. Graeber is certainly correct that, in any realistic model, the quantity of money is endogenously, not exogenously, determined, but that doesn’t mean that the value of gold and silver may not usefully be treated as exogenous in a system in which money is defined as a weight of gold or silver.

To put it bluntly: QTM is obviously wrong. Doubling the amount of gold in a country will have no effect on the price of cheese if you give all the gold to rich people and they just bury it in their yards, or use it to make gold-plated submarines (this is, incidentally, why quantitative easing, the strategy of buying long-term government bonds to put money into circulation, did not work either). What actually matters is spending.

Graeber is talking in circles, failing to distinguish between the quantity theory of money – a theory about the value of a pure medium of exchange with no use except to be received in exchange — and a theory of the real value of gold and silver when money is defined as a weight of gold or silver. The value of gold (or silver) in monetary uses must be roughly equal to its value in non-monetary uses. which is determined by the total stock of gold and the demand to hold gold or to use it in coinage or for other uses (e.g., jewelry and ornamentation). An increase in the stock of gold relative to demand must reduce its value. That relationship between price and quantity is not the same as QTM. The quantity of a metallic money will increase as its value in non-monetary uses declines. If there is literally an unlimited demand for newly mined gold to be immediately sent unused into hoards, Graeber’s argument would be correct. But the fact that much of the newly mined gold initially went into hoards does not mean that all of the newly mined gold went into hoards.

In sum, Graeber is confused between the quantity theory of money and a theory of a commodity money used both as money and as a real commodity. The quantity theory of money of a pure medium of exchange posits that changes in the quantity of money cause proportionate changes in the price level. Changes in the quantity of a real commodity also used as money have nothing to do with the quantity theory of money.

Relying on a dubious account of the history of monetary theory by Skidelsky, Graeber blames the obsession of economists with the quantity theory for repeated monetary disturbances starting with the late 17th century deflation in Britain when silver appreciated relative to gold causing prices measured in silver to fall. Graeber thus fails to see that under a metallic money, real disturbances do have repercussion on the level of prices, repercussions having nothing to do with an exogenous prior change in the quantity of money.

According to Skidelsky, the pattern was to repeat itself again and again, in 1797, the 1840s, the 1890s, and, ultimately, the late 1970s and early 1980s, with Thatcher and Reagan’s (in each case brief) adoption of monetarism. Always we see the same sequence of events:

(1) The government adopts hard-money policies as a matter of principle.

(2) Disaster ensues.

(3) The government quietly abandons hard-money policies.

(4) The economy recovers.

(5) Hard-money philosophy nonetheless becomes, or is reinforced as, simple universal common sense.

There is so much indiscriminate generalization here that it is hard to know what to make of it. But the conduct of monetary policy has always been fraught, and learning has been slow and painful. We can and must learn to do better, but blanket condemnations of economics are unlikely to lead to better outcomes.

How was it possible to justify such a remarkable string of failures? Here a lot of the blame, according to Skidelsky, can be laid at the feet of the Scottish philosopher David Hume. An early advocate of QTM, Hume was also the first to introduce the notion that short-term shocks—such as Locke produced—would create long-term benefits if they had the effect of unleashing the self-regulating powers of the market:

Actually I agree that Hume, as great and insightful a philosopher as he was and as sophisticated an economic observer as he was, was an unreliable monetary theorist. And one of the reasons he was led astray was his unwarranted attachment to the quantity theory of money, an attachment that was not shared by his close friend Adam Smith.

Ever since Hume, economists have distinguished between the short-run and the long-run effects of economic change, including the effects of policy interventions. The distinction has served to protect the theory of equilibrium, by enabling it to be stated in a form which took some account of reality. In economics, the short-run now typically stands for the period during which a market (or an economy of markets) temporarily deviates from its long-term equilibrium position under the impact of some “shock,” like a pendulum temporarily dislodged from a position of rest. This way of thinking suggests that governments should leave it to markets to discover their natural equilibrium positions. Government interventions to “correct” deviations will only add extra layers of delusion to the original one.

I also agree that focusing on long-run equilibrium without regard to short-run fluctuations can lead to terrible macroeconomic outcomes, but that doesn’t mean that long-run effects are never of concern and may be safely disregarded. But just as current suffering must not be disregarded when pursuing vague and uncertain long-term benefits, ephemeral transitory benefits shouldn’t obscure serious long-term consequences. Weighing such alternatives isn’t easy, but nothing is gained by denying that the alternatives exist. Making those difficult choices is inherent in policy-making, whether macroeconomic or climate policy-making.

Although Graeber takes a valid point – that a supposed tendency toward an optimal long-run equilibrium does not justify disregard of an acute short-term problem – to an extreme, his criticism of the New Classical approach to policy-making that replaced the flawed mainstream Keynesian macroeconomics of the late 1970s is worth listening to. The New Classical approach self-consciously rejected any policy aimed at short-run considerations owing to a time-inconsistency paradox was based almost entirely on the logic of general-equilibrium theory and an illegitimate methodological argument rejecting all macroeconomic theories not rigorously deduced from the unarguable axiom of optimizing behavior by rational agents (and therefore not, in the official jargon, microfounded) as unscientific and unworthy of serious consideration in the brave New Classical world of scientific macroeconomics.

It’s difficult for outsiders to see what was really at stake here, because the argument has come to be recounted as a technical dispute between the roles of micro- and macroeconomics. Keynesians insisted that the former is appropriate to studying the behavior of individual households or firms, trying to optimize their advantage in the marketplace, but that as soon as one begins to look at national economies, one is moving to an entirely different level of complexity, where different sorts of laws apply. Just as it is impossible to understand the mating habits of an aardvark by analyzing all the chemical reactions in their cells, so patterns of trade, investment, or the fluctuations of interest or employment rates were not simply the aggregate of all the microtransactions that seemed to make them up. The patterns had, as philosophers of science would put it, “emergent properties.” Obviously, it was necessary to understand the micro level (just as it was necessary to understand the chemicals that made up the aardvark) to have any chance of understand the macro, but that was not, in itself, enough.

As an aisde, it’s worth noting that the denial or disregard of the possibility of any emergent properties by New Classical economists (of which what came to be known as New Keynesian economics is really a mildly schismatic offshoot) is nicely illustrated by the un-self-conscious alacrity with which the representative-agent approach was adopted as a modeling strategy in the first few generations of New Classical models. That New Classical theorists now insist that representative agency is not an essential to New Classical modeling is true, but the methodologically reductive nature of New Classical macroeconomics, in which all macroeconomic theories must be derived under the axiom of individually maximizing behavior except insofar as specific “frictions” are introduced by explicit assumption, is essential. (See here, here, and here)

The counterrevolutionaries, starting with Keynes’s old rival Friedrich Hayek . . . took aim directly at this notion that national economies are anything more than the sum of their parts. Politically, Skidelsky notes, this was due to a hostility to the very idea of statecraft (and, in a broader sense, of any collective good). National economies could indeed be reduced to the aggregate effect of millions of individual decisions, and, therefore, every element of macroeconomics had to be systematically “micro-founded.”

Hayek’s role in the microfoundations movement is important, but his position was more sophisticated and less methodologically doctrinaire than that of the New Classical macroeconomists, if for no other reason than that Hayek didn’t believe that macroeconomics should, or could, be derived from general-equilibrium theory. His criticism, like that of economists like Clower and Leijonhufvud, of Keynesian macroeconomics for being insufficiently grounded in microeconomic principles, was aimed at finding microeconomic arguments that could explain and embellish and modify the propositions of Keynesian macroeconomic theory. That is the sort of scientific – not methodological — reductivism that Hayek’s friend Karl Popper advocated: a theoretical and empirical challenge of reducing a higher level theory to its more fundamental foundations, e.g., when physicists and chemists search for theoretical breakthroughs that allow the propositions of chemistry to be reduced to more fundamental propositions of physics. The attempt to reduce chemistry to underlying physical principles is very different from a methodological rejection of all chemistry that cannot be derived from underlying deep physical theories.

There is probably more than a grain of truth in Graeber’s belief that there was a political and ideological subtext in the demand for microfoundations by New Classical macroeconomists, but the success of the microfoundations program was also the result of philosophically unsophisticated methodological error. How to apportion the share of blame going to mistaken methodology, professional and academic opportunism, and a hidden political agenda is a question worthy of further investigation. The easy part is to identify the mistaken methodology, which Graeber does. As for the rest, Graeber simply asserts bad faith, but with little evidence.

In Graeber’s comprehensive condemnation of modern economics, the efficient market hypothesis, being closely related to the rational-expectations hypothesis so central to New Classical economics, is not spared either. Here again, though I share and sympathize with his disdain for EMH, Graeber can’t resist exaggeration.

In other words, we were obliged to pretend that markets could not, by definition, be wrong—if in the 1980s the land on which the Imperial compound in Tokyo was built, for example, was valued higher than that of all the land in New York City, then that would have to be because that was what it was actually worth. If there are deviations, they are purely random, “stochastic” and therefore unpredictable, temporary, and, ultimately, insignificant.

Of course, no one is obliged to pretend that markets could not be wrong — and certainly not by a definition. The EMH simply asserts that the price of an asset reflects all the publicly available information. But what EMH asserts is certainly not true in many or even most cases, because people with non-public information (or with superior capacity to process public information) may affect asset prices, and such people may profit at the expense of those less knowledgeable or less competent in anticipating price changes. Moreover, those advantages may result from (largely wasted) resources devoted to acquiring and processing information, and it is those people who make fortunes betting on the future course of asset prices.

Graeber then quotes Skidelsky approvingly:

There is a paradox here. On the one hand, the theory says that there is no point in trying to profit from speculation, because shares are always correctly priced and their movements cannot be predicted. But on the other hand, if investors did not try to profit, the market would not be efficient because there would be no self-correcting mechanism. . .

Secondly, if shares are always correctly priced, bubbles and crises cannot be generated by the market….

This attitude leached into policy: “government officials, starting with [Fed Chairman] Alan Greenspan, were unwilling to burst the bubble precisely because they were unwilling to even judge that it was a bubble.” The EMH made the identification of bubbles impossible because it ruled them out a priori.

So the apparent paradox that concerns Skidelsky and Graeber dissolves upon (only a modest amount of) further reflection. Proper understanding and revision of the EMH makes it clear that bubbles can occur. But that doesn’t mean that bursting bubbles is a job that can be safely delegated to any agency, including the Fed.

Moreover, the housing bubble peaked in early 2006, two and a half years before the financial crisis in September 2008. The financial crisis was not unrelated to the housing bubble, which undoubtedly added to the fragility of the financial system and its vulnerability to macroeconomic shocks, but the main cause of the crisis was Fed policy that was unnecessarily focused on a temporary blip in commodity prices persuading the Fed not to loosen policy in 2008 during a worsening recession. That was a scenario similar to the one in 1929 when concern about an apparent stock-market bubble caused the Fed to repeatedly tighten money, raising interest rates, thereby causing a downturn and crash of asset prices triggering the Great Depression.

Graeber and Skidelsky correctly identify some of the problems besetting macroeconomics, but their indiscriminate attack on all economic theory is unlikely to improve the situation. A pity, because a focused and sophisticated critique of economics than they have served up has never been more urgently needed than it is now to enable economists to perform the modest service to mankind of which they might be capable.

Rational Expectations, or, The Road to Incoherence

J. W. Mason left a very nice comment on my recent post about Paul Romer’s now-famous essay on macroeconomics, a comment now embedded in his interesting and insightful blog post on the Romer essay. As a wrote in my reply to Mason’s comment, I really liked the way he framed his point about rational expectations and intertemporal equilibrium. Sometimes when you see a familiar idea expressed in a particular way, the novelty of the expression, even though it’s not substantively different from other ways of expressing the idea, triggers a new insight. And that’s what I think happened in my own mind as I read Mason’s comment. Here’s what he wrote:

David Glasner’s interesting comment on Romer makes in passing a point that’s bugged me for years — that you can’t talk about transitions from one intertemporal equilibrium to another, there’s only the one. Or equivalently, you can’t have a model with rational expectations and then talk about what happens if there’s a “shock.” To say there is a shock in one period, is just to say that expectations in the previous period were wrong. Glasner:

the Lucas Critique applies even to micro-founded models, those models being strictly valid only in equilibrium settings and being unable to predict the adjustment of economies in the transition between equilibrium states. All models are subject to the Lucas Critique.

So the further point that I would make, after reading Mason’s comment, is just this. For an intertemporal equilibrium to exist, there must be a complete set of markets for all future periods and contingent states of the world, or, alternatively, there must be correct expectations shared by all agents about all future prices and the probability that each contingent future state of the world will be realized. By the way, If you think about it for a moment, the notion that probabilities can be assigned to every contingent future state of the world is mind-bogglingly unrealistic, because the number of contingent states must rapidly become uncountable, because every single contingency itself gives rise to further potential contingencies, and so on and on and on. But forget about that little complication. What intertemporal equilibrium requires is that all expectations of all individuals be in agreement – or at least not be inconsistent, some agents possibly having an incomplete set of expectations about future prices and future states of the world. If individuals differ in their expectations, so that their planned future purchases and sales are based on what they expect future prices to be when the time comes for those transactions to be carried out, then individuals will not be able to execute their plans as intended when at least one of them finds that actual prices are different from what they had been expected to be.

What this means is that expectations can be rational only when everyone has identical expectations. If people have divergent expectations, then the expectations of at least some people will necessarily be disappointed — the expectations of both people with differing expectations cannot be simultaneously realized — and those individuals whose expectations have been disappointed will have to revise their plans. But that means that the expectations of those people who were correct were also not rational, because the prices that they expected were not equilibrium prices. So unless all agents have the same expectations about the future, the expectations of no one are rational. Rational expectations are a fixed point, and that fixed point cannot be attained unless everyone shares those expectations.

Beyond that little problem, Mason raises the further problem that, in a rational-expectations equilibrium, it makes no sense to speak of a shock, because the only possible meaning of “shock” in the context of a full intertemporal (aka rational-expectations) equilibrium is a failure of expectations to be realized. But if expectations are not realized, expectations were not rational. So the whole New Classical modeling strategy of identifying shocks  to a system in rational-expectations equilibrium, and “predicting” the responses to these shocks as if they had been anticipated is self-contradictory and incoherent.

Paul Romer on Modern Macroeconomics, Or, the “All Models Are False” Dodge

Paul Romer has been engaged for some time in a worthy campaign against the travesty of modern macroeconomics. A little over a year ago I commented favorably about Romer’s takedown of Robert Lucas, but I also defended George Stigler against what I thought was an unfair attempt by Romer to identify George Stigler as an inspiration and role model for Lucas’s transgressions. Now just a week ago, a paper based on Romer’s Commons Memorial Lecture to the Omicron Delta Epsilon Society, has become just about the hottest item in the econ-blogosophere, even drawing the attention of Daniel Drezner in the Washington Post.

I have already written critically about modern macroeconomics in my five years of blogging, and here are some links to previous posts (link, link, link, link). It’s good to see that Romer is continuing to voice his criticisms, and that they are gaining a lot of attention. But the macroeconomic hierarchy is used to criticism, and has its standard responses to criticism, which are being dutifully deployed by defenders of the powers that be.

Romer’s most effective rhetorical strategy is to point out that the RBC core of modern DSGE models posit unobservable taste and technology shocks to account for fluctuations in the economic time series, but that these taste and technology shocks are themselves simply inferred from the fluctuations in the times-series data, so that the entire structure of modern macroeconometrics is little more than an elaborate and sophisticated exercise in question-begging.

In this post, I just want to highlight one of the favorite catch-phrases of modern macroeconomics which serves as a kind of default excuse and self-justification for the rampant empirical failures of modern macroeconomics (documented by Lipsey and Carlaw as I showed in this post). When confronted by evidence that the predictions of their models are wrong, the standard and almost comically self-confident response of the modern macroeconomists is: All models are false. By which the modern macroeconomists apparently mean something like: “And if they are all false anyway, you can’t hold us accountable, because any model can be proven wrong. What really matters is that our models, being microfounded, are not subject to the Lucas Critique, and since all other models than ours are not micro-founded, and, therefore, being subject to the Lucas Critique, they are simply unworthy of consideration. This is what I have called methodological arrogance. That response is simply not true, because the Lucas Critique applies even to micro-founded models, those models being strictly valid only in equilibrium settings and being unable to predict the adjustment of economies in the transition between equilibrium states. All models are subject to the Lucas Critique.

Here is Romer’s take:

In response to the observation that the shocks are imaginary, a standard defense invokes Milton Friedman’s (1953) methodological assertion from unnamed authority that “the more significant the theory, the more unrealistic the assumptions (p.14).” More recently, “all models are false” seems to have become the universal hand-wave for dismissing any fact that does not conform to the model that is the current favorite.

Friedman’s methodological assertion would have been correct had Friedman substituted “simple” for “unrealistic.” Sometimes simplifications are unrealistic, but they don’t have to be. A simplification is a generalization of something complicated. By simplifying, we can transform a problem that had been too complex to handle into a problem more easily analyzed. But such simplifications aren’t necessarily unrealistic. To say that all models are false is simply a dodge to avoid having to account for failure. The excuse of course is that all those other models are subject to the Lucas Critique, so my model wins. But your model is subject to the Lucas Critique even though you claim it’s not, so even according to the rules you have arbitrarily laid down, you don’t win.

So I was just curious about where the little phrase “all models are false” came from. I was expecting that Karl Popper might have said it, in which case to use the phrase as a defense mechanism against empirical refutation would have been a particularly fraudulent tactic, because it would have been a perversion of Popper’s methodological stance, which was to force our theoretical constructs to face up to, not to insulate it from, empirical testing. But when I googled “all theories are false” what I found was not Popper, but the British statistician, G. E. P. Box who wrote in his paper “Science and Statistics” based on his R. A. Fisher Memorial Lecture to the American Statistical Association: “All models are wrong.” Here’s the exact quote:

Since all models are wrong the scientist cannot obtain a “correct” one by excessive elaboration. On the contrary following William of Occam he should seek an economical description of natural phenomena. Just as the ability to devise simple but evocative models is the signature of the great scientist so overelaboration and overparameterization is often the mark of mediocrity.

Since all models are wrong the scientist must be alert to what is importantly wrong. It is inappropriate to be concerned about mice when there are tigers abroad. Pure mathematics is concerned with propositions like “given that A is true, does B necessarily follow?” Since the statement is a conditional one, it has nothing whatsoever to do with the truth of A nor of the consequences B in relation to real life. The pure mathematician, acting in that capacity, need not, and perhaps should not, have any contact with practical matters at all.

In applying mathematics to subjects such as physics or statistics we make tentative assumptions about the real world which we know are false but which we believe may be useful nonetheless. The physicist knows that particles have mass and yet certain results, approximating what really happens, may be derived from the assumption that they do not. Equally, the statistician knows, for example, that in nature there never was a normal distribution, there never was a straight line, yet with normal and linear assumptions, known to be false, he can often derive results which match, to a useful approximation, those found in the real world. It follows that, although rigorous derivation of logical consequences is of great importance to statistics, such derivations are necessarily encapsulated in the knowledge that premise, and hence consequence, do not describe natural truth.

It follows that we cannot know that any statistical technique we develop is useful unless we use it. Major advances in science and in the science of statistics in particular, usually occur, therefore, as the result of the theory-practice iteration.

One of the most annoying conceits of modern macroeconomists is the constant self-congratulatory references to themselves as scientists because of their ostentatious use of axiomatic reasoning, formal proofs, and higher mathematical techniques. The tiresome self-congratulation might get toned down ever so slightly if they bothered to read and take to heart Box’s lecture.

There Is No Intertemporal Budget Constraint

Last week Nick Rowe posted a link to a just published article in a special issue of the Review of Keynesian Economics commemorating the 80th anniversary of the General Theory. Nick’s article discusses the confusion in the General Theory between saving and hoarding, and Nick invited readers to weigh in with comments about his article. The ROKE issue also features an article by Simon Wren-Lewis explaining the eclipse of Keynesian theory as a result of the New Classical Counter-Revolution, correctly identified by Wren-Lewis as a revolution inspired not by empirical success but by a methodological obsession with reductive micro-foundationalism. While deploring the New Classical methodological authoritarianism, Wren-Lewis takes solace from the ability of New Keynesians to survive under the New Classical methodological regime, salvaging a role for activist counter-cyclical policy by, in effect, negotiating a safe haven for the sticky-price assumption despite its shaky methodological credentials. The methodological fiction that sticky prices qualify as micro-founded allowed New Keynesianism to survive despite the ascendancy of micro-foundationalist methodology, thereby enabling the core Keynesian policy message to survive.

I mention the Wren-Lewis article in this context because of an exchange between two of the commenters on Nick’s article: the presumably pseudonymous Avon Barksdale and blogger Jason Smith about microfoundations and Keynesian economics. Avon began by chastising Nick for wasting time discussing Keynes’s 80-year old ideas, something Avon thinks would never happen in a discussion about a true science like physics, the 100-year-old ideas of Einstein being of no interest except insofar as they have been incorporated into the theoretical corpus of modern physics. Of course, this is simply vulgar scientism, as if the only legitimate way to do economics is to mimic how physicists do physics. This methodological scolding is typically charming New Classical arrogance. Sort of reminds one of how Friedrich Engels described Marxian theory as scientific socialism. I mean who, other than a religious fanatic, would be stupid enough to argue with the assertions of science?

Avon continues with a quotation from David Levine, a fine economist who has done a lot of good work, but who is also enthralled by the New Classical methodology. Avon’s scientism provoked the following comment from Jason Smith, a Ph. D. in physics with a deep interest in and understanding of economics.

You quote from Levine: “Keynesianism as argued by people such as Paul Krugman and Brad DeLong is a theory without people either rational or irrational”

This is false. The L in ISLM means liquidity preference and e.g. here …

http://krugman.blogs.nytimes.com/2013/11/18/the-new-keynesian-case-for-fiscal-policy-wonkish/

… Krugman mentions an Euler equation. The Euler equation essentially says that an agent must be indifferent between consuming one more unit today on the one hand and saving that unit and consuming in the future on the other if utility is maximized.

So there are agents in both formulations preferring one state of the world relative to others.

Avon replied:

Jason,

“This is false. The L in ISLM means liquidity preference and e.g. here”

I know what ISLM is. It’s not recursive so it really doesn’t have people in it. The dynamics are not set by any micro-foundation. If you’d like to see models with people in them, try Ljungqvist and Sargent, Recursive Macroeconomic Theory.

To which Jason retorted:

Avon,

So the definition of “people” is restricted to agents making multi-period optimizations over time, solving a dynamic programming problem?

Well then any such theory is obviously wrong because people don’t behave that way. For example, humans don’t optimize the dictator game. How can you add up optimizing agents and get a result that is true for non-optimizing agents … coincident with the details of the optimizing agents mattering.

Your microfoundation requirement is like saying the ideal gas law doesn’t have any atoms in it. And it doesn’t! It is an aggregate property of individual “agents” that don’t have properties like temperature or pressure (or even volume in a meaningful sense). Atoms optimize entropy, but not out of any preferences.

So how do you know for a fact that macro properties like inflation or interest rates are directly related to agent optimizations? Maybe inflation is like temperature — it doesn’t exist for individuals and is only a property of economics in aggregate.

These questions are not answered definitively, and they’d have to be to enforce a requirement for microfoundations … or a particular way of solving the problem.

Are quarks important to nuclear physics? Not really — it’s all pions and nucleons. Emergent degrees of freedom. Sure, you can calculate pion scattering from QCD lattice calculations (quark and gluon DoF), but it doesn’t give an empirically better result than chiral perturbation theory (pion DoF) that ignores the microfoundations (QCD).

Assuming quarks are required to solve nuclear physics problems would have been a giant step backwards.

To which Avon rejoined:

Jason

The microfoundation of nuclear physics and quarks is quantum mechanics and quantum field theory. How the degrees of freedom reorganize under the renormalization group flow, what effective field theory results is an empirical question. Keynesian economics is worse tha[n] useless. It’s wrong empirically, it has no theoretical foundation, it has no laws. It has no microfoundation. No serious grad school has taught Keynesian economics in nearly 40 years.

To which Jason answered:

Avon,

RG flow is irrelevant to chiral perturbation theory which is based on the approximate chiral symmetry of QCD. And chiral perturbation theory could exist without QCD as the “microfoundation”.

Quantum field theory is not a ‘microfoundation’, but rather a framework for building theories that may or may not have microfoundations. As Weinberg (1979) said:

” … quantum field theory itself has no content beyond analyticity, unitarity,
cluster decomposition, and symmetry.”

If I put together an NJL model, there is no requirement that the scalar field condensate be composed of quark-antiquark pairs. In fact, the basic idea was used for Cooper pairs as a model of superconductivity. Same macro theory; different microfoundations. And that is a general problem with microfoundations — different microfoundations can lead to the same macro theory, so which one is right?

And the IS-LM model is actually pretty empirically accurate (for economics):

http://informationtransfereconomics.blogspot.com/2014/03/the-islm-model-again.html

To which Avon responded:

First, ISLM analysis does not hold empirically. It just doesn’t work. That’s why we ended up with the macro revolution of the 70s and 80s. Keynesian economics ignores intertemporal budget constraints, it violates Ricardian equivalence. It’s just not the way the world works. People might not solve dynamic programs to set their consumption path, but at least these models include a future which people plan over. These models work far better than Keynesian ISLM reasoning.

As for chiral perturbation theory and the approximate chiral symmetries of QCD, I am not making the case that NJL models requires QCD. NJL is an effective field theory so it comes from something else. That something else happens to be QCD. It could have been something else, that’s an empirical question. The microfoundation I’m talking about with theories like NJL is QFT and the symmetries of the vacuum, not the short distance physics that might be responsible for it. The microfoundation here is about the basic laws, the principles.

ISLM and Keynesian economics has none of this. There is no principle. The microfoundation of modern macro is not about increasing the degrees of freedom to model every person in the economy on some short distance scale, it is about building the basic principles from consistent economic laws that we find in microeconomics.

Well, I totally agree that IS-LM is a flawed macroeconomic model, and, in its original form, it was borderline-incoherent, being a single-period model with an interest rate, a concept without meaning except as an intertemporal price relationship. These deficiencies of IS-LM became obvious in the 1970s, so the model was extended to include a future period, with an expected future price level, making it possible to speak meaningfully about real and nominal interest rates, inflation and an equilibrium rate of spending. So the failure of IS-LM to explain stagflation, cited by Avon as the justification for rejecting IS-LM in favor of New Classical macro, was not that hard to fix, at least enough to make it serviceable. And comparisons of the empirical success of augmented IS-LM and the New Classical models have shown that IS-LM models consistently outperform New Classical models.

What Avon fails to see is that the microfoundations that he considers essential for macroeconomics are themselves derived from the assumption that the economy is operating in macroeconomic equilibrium. Thus, insisting on microfoundations – at least in the formalist sense that Avon and New Classical macroeconomists understand the term – does not provide a foundation for macroeconomics; it is just question begging aka circular reasoning or petitio principia.

The circularity is obvious from even a cursory reading of Samuelson’s Foundations of Economic Analysis, Robert Lucas’s model for doing economics. What Samuelson called meaningful theorems – thereby betraying his misguided acceptance of the now discredited logical positivist dogma that only potentially empirically verifiable statements have meaning – are derived using the comparative-statics method, which involves finding the sign of the derivative of an endogenous economic variable with respect to a change in some parameter. But the comparative-statics method is premised on the assumption that before and after the parameter change the system is in full equilibrium or at an optimum, and that the equilibrium, if not unique, is at least locally stable and the parameter change is sufficiently small not to displace the system so far that it does not revert back to a new equilibrium close to the original one. So the microeconomic laws invoked by Avon are valid only in the neighborhood of a stable equilibrium, and the macroeconomics that Avon’s New Classical mentors have imposed on the economics profession is a macroeconomics that, by methodological fiat, is operative only in the neighborhood of a locally stable equilibrium.

Avon dismisses Keynesian economics because it ignores intertemporal budget constraints. But the intertemporal budget constraint doesn’t exist in any objective sense. Certainly macroeconomics has to take into account intertemporal choice, but the idea of an intertemporal budget constraint analogous to the microeconomic budget constraint underlying the basic theory of consumer choice is totally misguided. In the static theory of consumer choice, the consumer has a given resource endowment and known prices at which consumers can transact at will, so the utility-maximizing vector of purchases and sales can be determined as the solution of a constrained-maximization problem.

In the intertemporal context, consumers have a given resource endowment, but prices are not known. So consumers have to make current transactions based on their expectations about future prices and a variety of other circumstances about which consumers can only guess. Their budget constraints are thus not real but totally conjectural based on their expectations of future prices. The optimizing Euler equations are therefore entirely conjectural as well, and subject to continual revision in response to changing expectations. The idea that the microeconomic theory of consumer choice is straightforwardly applicable to the intertemporal choice problem in a setting in which consumers don’t know what future prices will be and agents’ expectations of future prices are a) likely to be very different from each other and thus b) likely to be different from their ultimate realizations is a huge stretch. The intertemporal budget constraint has a completely different role in macroeconomics from the role it has in microeconomics.

If I expect that the demand for my services will be such that my disposable income next year would be $500k, my consumption choices would be very different from what they would have been if I were expecting a disposable income of $100k next year. If I expect a disposable income of $500k next year, and it turns out that next year’s income is only $100k, I may find myself in considerable difficulty, because my planned expenditure and the future payments I have obligated myself to make may exceed my disposable income or my capacity to borrow. So if there are a lot of people who overestimate their future incomes, the repercussions of their over-optimism may reverberate throughout the economy, leading to bankruptcies and unemployment and other bad stuff.

A large enough initial shock of mistaken expectations can become self-amplifying, at least for a time, possibly resembling the way a large initial displacement of water can generate a tsunami. A financial crisis, which is hard to model as an equilibrium phenomenon, may rather be an emergent phenomenon with microeconomic sources, but whose propagation can’t be described in microeconomic terms. New Classical macroeconomics simply excludes such possibilities on methodological grounds by imposing a rational-expectations general-equilibrium structure on all macroeconomic models.

This is not to say that the rational expectations assumption does not have a useful analytical role in macroeconomics. But the most interesting and most important problems in macroeconomics arise when the rational expectations assumption does not hold, because it is when individual expectations are very different and very unstable – say, like now, for instance — that macroeconomies become vulnerable to really scary instability.

Simon Wren-Lewis makes a similar point in his paper in the Review of Keynesian Economics.

Much discussion of current divisions within macroeconomics focuses on the ‘saltwater/freshwater’ divide. This understates the importance of the New Classical Counter Revolution (hereafter NCCR). It may be more helpful to think about the NCCR as involving two strands. The one most commonly talked about involves Keynesian monetary and fiscal policy. That is of course very important, and plays a role in the policy reaction to the recent Great Recession. However I want to suggest that in some ways the second strand, which was methodological, is more important. The NCCR helped completely change the way academic macroeconomics is done.

Before the NCCR, macroeconomics was an intensely empirical discipline: something made possible by the developments in statistics and econometrics inspired by The General Theory. After the NCCR and its emphasis on microfoundations, it became much more deductive. As Hoover (2001, p. 72) writes, ‘[t]he conviction that macroeconomics must possess microfoundations has changed the face of the discipline in the last quarter century’. In terms of this second strand, the NCCR was triumphant and remains largely unchallenged within mainstream academic macroeconomics.

Perhaps I will have some more to say about Wren-Lewis’s article in a future post. And perhaps also about Nick Rowe’s article.

HT: Tom Brown

Update (02/11/16):

On his blog Jason Smith provides some further commentary on his exchange with Avon on Nick Rowe’s blog, explaining at greater length how irrelevant microfoundations are to doing real empirically relevant physics. He also expands on and puts into a broader meta-theoretical context my point about the extremely narrow range of applicability of the rational-expectations equilibrium assumptions of New Classical macroeconomics.

David Glasner found a back-and-forth between me and a commenter (with the pseudonym “Avon Barksdale” after [a] character on The Wire who [didn’t end] up taking an economics class [per Tom below]) on Nick Rowe’s blog who expressed the (widely held) view that the only scientific way to proceed in economics is with rigorous microfoundations. “Avon” held physics up as a purported shining example of this approach.
I couldn’t let it go: even physics isn’t that reductionist. I gave several examples of cases where the microfoundations were actually known, but not used to figure things out: thermodynamics, nuclear physics. Even modern physics is supposedly built on string theory. However physicists do not require every pion scattering amplitude be calculated from QCD. Some people do do so-called lattice calculations. But many resort to the “effective” chiral perturbation theory. In a sense, that was what my thesis was about — an effective theory that bridges the gap between lattice QCD and chiral perturbation theory. That effective theory even gave up on one of the basic principles of QCD — confinement. It would be like an economist giving up opportunity cost (a basic principle of the micro theory). But no physicist ever said to me “your model is flawed because it doesn’t have true microfoundations”. That’s because the kind of hard core reductionism that surrounds the microfoundations paradigm doesn’t exist in physics — the most hard core reductionist natural science!
In his post, Glasner repeated something that he had before and — probably because it was in the context of a bunch of quotes about physics — I thought of another analogy.

Glasner says:

But the comparative-statics method is premised on the assumption that before and after the parameter change the system is in full equilibrium or at an optimum, and that the equilibrium, if not unique, is at least locally stable and the parameter change is sufficiently small not to displace the system so far that it does not revert back to a new equilibrium close to the original one. So the microeconomic laws invoked by Avon are valid only in the neighborhood of a stable equilibrium, and the macroeconomics that Avon’s New Classical mentors have imposed on the economics profession is a macroeconomics that, by methodological fiat, is operative only in the neighborhood of a locally stable equilibrium.

 

This hits on a basic principle of physics: any theory radically simplifies near an equilibrium.

Go to Jason’s blog to read the rest of his important and insightful post.

Representative Agents, Homunculi and Faith-Based Macroeconomics

After my previous post comparing the neoclassical synthesis in its various versions to the mind-body problem, there was an interesting Twitter exchange between Steve Randy Waldman and David Andolfatto in which Andolfatto queried whether Waldman and I are aware that there are representative-agent models in which the equilibrium is not Pareto-optimal. Andalfatto raised an interesting point, but what I found interesting about it might be different from what Andalfatto was trying to show, which, I am guessing, was that a representative-agent modeling strategy doesn’t necessarily commit the theorist to the conclusion that the world is optimal and that the solutions of the model can never be improved upon by a monetary/fiscal-policy intervention. I concede the point. It is well-known I think that, given the appropriate assumptions, a general-equilibrium model can have a sub-optimal solution. Given those assumptions, the corresponding representative-agent will also choose a sub-optimal solution. So I think I get that, but perhaps there’s a more subtle point  that I’m missing. If so, please set me straight.

But what I was trying to argue was not that representative-agent models are necessarily optimal, but that representative-agent models suffer from an inherent, and, in my view, fatal, flaw: they can’t explain any real macroeconomic phenomenon, because a macroeconomic phenomenon has to encompass something more than the decision of a single agent, even an omniscient central planner. At best, the representative agent is just a device for solving an otherwise intractable general-equilibrium model, which is how I think Lucas originally justified the assumption.

Yet just because a general-equilibrium model can be formulated so that it can be solved as the solution of an optimizing agent does not explain the economic mechanism or process that generates the solution. The mathematical solution of a model does not necessarily provide any insight into the adjustment process or mechanism by which the solution actually is, or could be, achieved in the real world. Your ability to find a solution for a mathematical problem does not mean that you understand the real-world mechanism to which the solution of your model corresponds. The correspondence between your model may be a strictly mathematical correspondence which may not really be in any way descriptive of how any real-world mechanism or process actually operates.

Here’s an example of what I am talking about. Consider a traffic-flow model explaining how congestion affects vehicle speed and the flow of traffic. It seems obvious that traffic congestion is caused by interactions between the different vehicles traversing a thoroughfare, just as it seems obvious that market exchange arises as the result of interactions between the different agents seeking to advance their own interests. OK, can you imagine building a useful traffic-flow model based on solving for the optimal plan of a representative vehicle?

I don’t think so. Once you frame the model in terms of a representative vehicle, you have abstracted from the phenomenon to be explained. The entire exercise would be pointless – unless, that is, you assumed that interactions between vehicles are so minimal that they can be ignored. But then why would you be interested in congestion effects? If you want to claim that your model has any relevance to the effect of congestion on traffic flow, you can’t base the claim on an assumption that there is no congestion.

Or to take another example, suppose you want to explain the phenomenon that, at sporting events, all, or almost all, the spectators sit in their seats but occasionally get up simultaneously from their seats to watch the play on the field or court. Would anyone ever think that an explanation in terms of a representative spectator could explain that phenomenon?

In just the same way, a representative-agent macroeconomic model necessarily abstracts from the interactions between actual agents. Obviously, by abstracting from the interactions, the model can’t demonstrate that there are no interactions between agents in the real world or that their interactions are too insignificant to matter. I would be shocked if anyone really believed that the interactions between agents are unimportant, much less, negligible; nor have I seen an argument that interactions between agents are unimportant, the concept of network effects, to give just one example, being an important topic in microeconomics.

It’s no answer to say that all the interactions are accounted for within the general-equilibrium model. That is just a form of question-begging. The representative agent is being assumed because without him the problem of finding a general-equilibrium solution of the model is very difficult or intractable. Taking into account interactions makes the model too complicated to work with analytically, so it is much easier — but still hard enough to allow the theorist to perform some fancy mathematical techniques — to ignore those pesky interactions. On top of that, the process by which the real world arrives at outcomes to which a general-equilibrium model supposedly bears at least some vague resemblance can’t even be described by conventional modeling techniques.

The modeling approach seems like that of a neuroscientist saying that, because he could simulate the functions, electrical impulses, chemical reactions, and neural connections in the brain – which he can’t do and isn’t even close to doing, even though a neuroscientist’s understanding of the brain far surpasses any economist’s understanding of the economy – he can explain consciousness. Simulating the operation of a brain would not explain consciousness, because the computer on which the neuroscientist performed the simulation would not become conscious in the course of the simulation.

Many neuroscientists and other materialists like to claim that consciousness is not real, that it’s just an epiphenomenon. But we all have the subjective experience of consciousness, so whatever it is that someone wants to call it, consciousness — indeed the entire world of mental phenomena denoted by that term — remains an unexplained phenomenon, a phenomenon that can only be dismissed as unreal on the basis of a metaphysical dogma that denies the existence of anything that can’t be explained as the result of material and physical causes.

I call that metaphysical belief a dogma not because it’s false — I have no way of proving that it’s false — but because materialism is just as much a metaphysical belief as deism or monotheism. It graduates from belief to dogma when people assert not only that the belief is true but that there’s something wrong with you if you are unwilling to believe it as well. The most that I would say against the belief in materialism is that I can’t understand how it could possibly be true. But I admit that there are a lot of things that I just don’t understand, and I will even admit to believing in some of those things.

New Classical macroeconomists, like, say, Robert Lucas and, perhaps, Thomas Sargent, like to claim that unless a macroeconomic model is microfounded — by which they mean derived from an explicit intertemporal optimization exercise typically involving a representative agent or possibly a small number of different representative agents — it’s not an economic model, because the model, being vulnerable to the Lucas critique, is theoretically superficial and vacuous. But only models of intertemporal equilibrium — a set of one or more mutually consistent optimal plans — are immune to the Lucas critique, so insisting on immunity to the Lucas critique as a prerequisite for a macroeconomic model is a guarantee of failure if your aim to explain anything other than an intertemporal equilibrium.

Unless, that is, you believe that real world is in fact the realization of a general equilibrium model, which is what real-business-cycle theorists, like Edward Prescott, at least claim to believe. Like materialist believers that all mental states are epiphenomenous, and that consciousness is an (unexplained) illusion, real-business-cycle theorists purport to deny that there is such a thing as a disequilibrium phenomenon, the so-called business cycle, in their view, being nothing but a manifestation of the intertemporal-equilibrium adjustment of an economy to random (unexplained) productivity shocks. According to real-business-cycle theorists, such characteristic phenomena of business cycles as surprise, regret, disappointed expectations, abandoned and failed plans, the inability to find work at wages comparable to wages that other similar workers are being paid are not real phenomena; they are (unexplained) illusions and misnomers. The real-business-cycle theorists don’t just fail to construct macroeconomic models; they deny the very existence of macroeconomics, just as strict materialists deny the existence of consciousness.

What is so preposterous about the New-Classical/real-business-cycle methodological position is not the belief that the business cycle can somehow be modeled as a purely equilibrium phenomenon, implausible as that idea seems, but the insistence that only micro-founded business-cycle models are methodologically acceptable. It is one thing to believe that ultimately macroeconomics and business-cycle theory will be reduced to the analysis of individual agents and their interactions. But current micro-founded models can’t provide explanations for what many of us think are basic features of macroeconomic and business-cycle phenomena. If non-micro-founded models can provide explanations for those phenomena, even if those explanations are not fully satisfactory, what basis is there for rejecting them just because of a methodological precept that disqualifies all non-micro-founded models?

According to Kevin Hoover, the basis for insisting that only micro-founded macroeconomic models are acceptable, even if the microfoundation consists in a single representative agent optimizing for an entire economy, is eschatological. In other words, because of a belief that economics will eventually develop analytical or computational techniques sufficiently advanced to model an entire economy in terms of individual interacting agents, an analysis based on a single representative agent, as the first step on this theoretical odyssey, is somehow methodologically privileged over alternative models that do not share that destiny. Hoover properly rejects the presumptuous notion that an avowed, but unrealized, theoretical destiny, can provide a privileged methodological status to an explanatory strategy. The reductionist microfoundationalism of New-Classical macroeconomics and real-business-cycle theory, with which New Keynesian economists have formed an alliance of convenience, is truly a faith-based macroeconomics.

The remarkable similarity between the reductionist microfoundational methodology of New-Classical macroeconomics and the reductionist materialist approach to the concept of mind suggests to me that there is also a close analogy between the representative agent and what philosophers of mind call a homunculus. The Cartesian materialist theory of mind maintains that, at some place or places inside the brain, there resides information corresponding to our conscious experience. The question then arises: how does our conscious experience access the latent information inside the brain? And the answer is that there is a homunculus (or little man) that processes the information for us so that we can perceive it through him. For example, the homunculus (see the attached picture of the little guy) views the image cast by light on the retina as if he were watching a movie projected onto a screen.

homunculus

But there is an obvious fallacy, because the follow-up question is: how does our little friend see anything? Well, the answer must be that there’s another, smaller, homunculus inside his brain. You can probably already tell that this argument is going to take us on an infinite regress. So what purports to be an explanation turns out to be just a form of question-begging. Sound familiar? The only difference between the representative agent and the homunculus is that the representative agent begs the question immediately without having to go on an infinite regress.

PS I have been sidetracked by other responsibilities, so I have not been blogging much, if at all, for the last few weeks. I hope to post more frequently, but I am afraid that my posting and replies to comments are likely to remain infrequent for the next couple of months.

All New Classical Models Are Subject to the Lucas Critique

Almost 40 years ago, Robert Lucas made a huge, but not quite original, contribution, when he provided a very compelling example of how the predictions of the then standard macroeconometric models used for policy analysis were inherently vulnerable to shifts in the empirically estimated parameters contained in the models, shifts induced by the very policy change under consideration. Insofar as those models could provide reliable forecasts of the future course of the economy, it was because the policy environment under which the parameters of the model had been estimated was not changing during the time period for which the forecasts were made. But any forecast deduced from the model conditioned on a policy change would necessarily be inaccurate, because the policy change itself would cause the agents in the model to alter their expectations in light of the policy change, causing the parameters of the model to diverge from their previously estimated values. Lucas concluded that only models based on deep parameters reflecting the underlying tastes, technology, and resource constraints under which agents make decisions could provide a reliable basis for policy analysis.

The Lucas critique undoubtedly conveyed an important insight about how to use econometric models in analyzing the effects of policy changes, and if it did no more than cause economists to be more cautious in offering policy advice based on their econometric models and policy makers to more skeptical about the advice they got from economists using such models, the Lucas critique would have performed a very valuable public service. Unfortunately, the lesson that the economics profession learned from the Lucas critique went far beyond that useful warning about the reliability of conditional forecasts potentially sensitive to unstable parameter estimates. In an earlier post, I discussed another way in which the Lucas Critique has been misapplied. (One responsible way to deal with unstable parameter estimates would be make forecasts showing a range of plausible outcome depending on how parameter estimates might change as a result of the policy change. Such an approach is inherently messy, and, at least in the short run, would tend to make policy makers less likely to pay attention to the policy advice of economists. But the inherent sensitivity of forecasts to unstable model parameters ought to make one skeptical about the predictions derived from any econometric model.)

Instead, the Lucas critique was used by Lucas and his followers as a tool by which to advance a reductionist agenda of transforming macroeconomics into a narrow slice of microeconomics, the slice being applied general-equilibrium theory in which the models required drastic simplification before they could generate quantitative predictions. The key to deriving quantitative results from these models is to find an optimal intertemporal allocation of resources given the specified tastes, technology and resource constraints, which is typically done by describing the model in terms of an optimizing representative agent with a utility function, a production function, and a resource endowment. A kind of hand-waving is performed via the rational-expectations assumption, thereby allowing the optimal intertemporal allocation of the representative agent to be identified as a composite of the mutually compatible optimal plans of a set of decentralized agents, the hand-waving being motivated by the Arrow-Debreu welfare theorems proving that any Pareto-optimal allocation can be sustained by a corresponding equilibrium price vector. Under rational expectations, agents correctly anticipate future equilibrium prices, so that market-clearing prices in the current period are consistent with full intertemporal equilibrium.

What is amazing – mind-boggling might be a more apt adjective – is that this modeling strategy is held by Lucas and his followers to be invulnerable to the Lucas critique, being based supposedly on deep parameters reflecting nothing other than tastes, technology and resource endowments. The first point to make – there are many others, but we needn’t exhaust the list – is that it is borderline pathological to convert a valid and important warning about how economic models may be subject to misunderstanding or misuse as a weapon with which to demolish any model susceptible of such misunderstanding or misuse as a prelude to replacing those models by the class of reductionist micromodels that now pass for macroeconomics.

But there is a second point to make, which is that the reductionist models adopted by Lucas and his followers are no less vulnerable to the Lucas critique than the models they replaced. All the New Classical models are explicitly conditioned on the assumption of optimality. It is only by positing an optimal solution for the representative agent that the equilibrium price vector can be inferred. The deep parameters of the model are conditioned on the assumption of optimality and the existence of an equilibrium price vector supporting that equilibrium. If the equilibrium does not obtain – the optimal plans of the individual agents or the fantastical representative agent becoming incapable of execution — empirical estimates of the parameters of the model parameters cannot correspond to the equilibrium values implied by the model itself. Parameter estimates are therefore sensitive to how closely the economic environment in which the parameters were estimated corresponded to conditions of equilibrium. If the conditions under which the parameters were estimated more nearly approximated the conditions of equilibrium than the period in which the model is being used to make conditional forecasts, those forecasts, from the point of view of the underlying equilibrium model, must be inaccurate. The Lucas critique devours its own offspring.


About Me

David Glasner
Washington, DC

I am an economist in the Washington DC area. My research and writing has been mostly on monetary economics and policy and the history of economics. 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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