Archive for the 'Keynes' Category

What’s Wrong with Econ 101?

Hendrickson responded recently to criticisms of Econ 101 made by Noah Smith and Mark Thoma. Mark Thoma thinks that Econ 101 has a conservative bias, presumably because Econ 101 teaches students that markets equilibrate supply and demand and allocate resources to their highest valued use and that sort of thing. If markets are so wonderful, then shouldn’t we keep hands off the market and let things take care of themselves? Noah Smith is especially upset that Econ 101, slighting the ambiguous evidence that minimum-wage laws actually do increase unemployment, is too focused on theory and pays too little attention to empirical techniques.

I sympathize with Josh defense of Econ 101, and I think he makes a good point that there is nothing in Econ 101 that quantifies the effect on unemployment of minimum-wage legislation, so that the disconnect between theory and evidence isn’t as stark as Noah suggests. Josh also emphasizes, properly, that whatever the effect of an increase in the minimum wage implied by economic theory, that implication by itself can’t tell us whether the minimum wage should be raised. An ought statement can’t be derived from an is statement. Philosophers are not as uniformly in agreement about the positive-normative distinction as they used to be, but I am old-fashioned enough to think that it’s still valid. If there is a conservative bias in Econ 101, the problem is not Econ 101; the problem is bad teaching.

Having said all that, however, I don’t think that Josh’s defense addresses the real problems with Econ 101. Noah Smith’s complaints about the implied opposition of Econ 101 to minimum-wage legislation and Mark Thoma’s about the conservative bias of Econ 101 are symptoms of a deeper problem with Econ 101, a problem inherent in the current state of economic theory, and unlikely to go away any time soon.

The deeper problem that I think underlies much of the criticism of Econ 101 is the fragility of its essential propositions. These propositions, what Paul Samuelson misguidedly called “meaningful theorems” are deducible from the basic postulates of utility maximization and wealth maximization by applying the method of comparative statics. Not only are the propositions based on questionable psychological assumptions, the comparative-statics method imposes further restrictive assumptions designed to isolate a single purely theoretical relationship. The assumptions aren’t just the kind of simplifications necessary for the theoretical models of any empirical science to be applicable to the real world, they subvert the powerful logic used to derive those implications. It’s not just that the assumptions may not be fully consistent with the conditions actually observed, but the implications of the model are themselves highly sensitive to those assumptions. The meaningful theorems themselves are very sensitive to the assumptions of the model.

The bread and butter of Econ 101 is the microeconomic theory of market adjustment in which price and quantity adjust to equilibrate what consumers demand with what suppliers produce. This is the partial-equilibrium analysis derived from Alfred Marshall, and gradually perfected in the 1920s and 1930s after Marshall’s death with the development of the theories of the firm, and perfect and imperfect competition. As I have pointed out before in a number of posts just as macroeconomics depends on microfoundations, microeconomics depends on macrofoundations (e.g. here and here). All partial-equilibrium analysis relies on the – usually implicit — assumption that all markets but the single market under analysis are in equilibrium. Without that assumption, it is logically impossible to derive any of Samuelson’s meaningful theorems, and the logical necessity of microeconomics is severely compromised.

The underlying idea is very simple. Samuelson’s meaningful theorems are meant to isolate the effect of a change in a single parameter on a particular endogenous variable in an economic system. The only way to isolate the effect of the parameter on the variable is to start from an equilibrium state in which the system is, as it were, at rest. A small (aka infinitesimal) change in the parameter induces an adjustment in the equilibrium, and a comparison of the small change in the variable of interest between the new equilibrium and the old equilibrium relative to the parameter change identifies the underlying relationship between the variable and the parameter, all else being held constant. If the analysis did not start from equilibrium, then the effect of the parameter change on the variable could not be isolated, because the variable would be changing for reasons having nothing to do with the parameter change, making it impossible to isolate the pure effect of the parameter change on the variable of interest.

Not only must the exercise start from an equilibrium state, the equilibrium must be at least locally stable, so that the posited small parameter change doesn’t cause the system to gravitate towards another equilibrium — the usual assumption of a unique equilibrium being an assumption to ensure tractability rather than a deduction from any plausible assumptions – or simply veer off on some explosive or indeterminate path.

Even aside from all these restrictive assumptions, the standard partial-equilibrium analysis is restricted to markets that can be assumed to be very small relative to the entire system. For small markets, it is safe to assume that the small changes in the single market under analysis will have sufficiently small effects on all the other markets in the economy that the induced effects on all the other markets from the change in the market of interest have a negligible feedback effect on the market of interest.

But the partial-equilibrium method surely breaks down when the market under analysis is a market that is large relative to the entire economy, like, shall we say, the market for labor. The feedback effects are simply too strong for the small-market assumptions underlying the partial-equilibrium analysis to be satisfied by the labor market. But even aside from the size issue, the essence of the partial-equilibrium method is the assumption that all markets other than the market under analysis are in equilibrium. But the very assumption that the labor market is not in equilibrium renders the partial-equilibrium assumption that all other markets are in equilibrium untenable. I would suggest that the proper way to think about what Keynes was trying, not necessarily successfully, to do in the General Theory when discussing nominal wage cuts as a way to reduce unemployment is to view that discussion as a critique of using the partial-equilibrium method to analyze a state of general unemployment, as opposed to a situation in which unemployment is confined to a particular occupation or a particular geographic area.

So the question naturally arises: If the logical basis of Econ 101 is as flimsy as I have been suggesting, should we stop teaching Econ 101? My answer is an emphatic, but qualified, no. Econ 101 is the distillation of almost a century and a half of rigorous thought about how to analyze human behavior. What we have come up with so far is very imperfect, but it is still the most effective tool we have for systematically thinking about human conduct and its consequences, especially its unintended consequences. But we should be more forthright about its limitations and the nature of the assumptions that underlie the analysis. We should also be more aware of the logical gaps between the theory – Samuelson’s meaningful theorems — and the applications of the theory.

In fact, many meaningful theorems are consistently corroborated by statistical tests, presumably because observations by and large occur when the economy operates in the neighborhood of a general equililbrium and feedback effect are small, so that the extraneous forces – other than those derived from theory – impinge on actual observations more or less randomly, and thus don’t significantly distort the predicted relationship. And undoubtedly there are also cases in which the random effects overwhelm the theoretically identified relationships, preventing the relationships from being identified statistically, at least when the number of observations is relatively small as is usually the case with economic data. But we should also acknowledge that the theoretically predicted relationships may simply not hold in the real world, because the extreme conditions required for the predicted partial-equilibrium relationships to hold – near-equilibrium conditions and the absence of feedback effects – may often not be satisfied.

What’s Wrong with Monetarism?

UPDATE: (05/06): In an email Richard Lipsey has chided me for seeming to endorse the notion that 1970s stagflation refuted Keynesian economics. Lipsey rightly points out that by introducing inflation expectations into the Phillips Curve or the Aggregate Supply Curve, a standard Keynesian model is perfectly capable of explaining stagflation, so that it is simply wrong to suggest that 1970s stagflation constituted an empirical refutation of Keynesian theory. So my statement in the penultimate paragraph that the k-percent rule

was empirically demolished in the 1980s in a failure even more embarrassing than the stagflation failure of Keynesian economics.

should be amended to read “the supposed stagflation failure of Keynesian economics.”

Brad DeLong recently did a post (“The Disappearance of Monetarism”) referencing an old (apparently unpublished) paper of his following up his 2000 article (“The Triumph of Monetarism”) in the Journal of Economic Perspectives. Paul Krugman added his own gloss on DeLong on Friedman in a post called “Why Monetarism Failed.” In the JEP paper, DeLong argued that the New Keynesian policy consensus of the 1990s was built on the foundation of what DeLong called “classic monetarism,” the analytical core of the doctrine developed by Friedman in the 1950s and 1960s, a core that survived the demise of what he called “political monetarism,” the set of factual assumptions and policy preferences required to justify Friedman’s k-percent rule as the holy grail of monetary policy.

In his follow-up paper, DeLong balanced his enthusiasm for Friedman with a bow toward Keynes, noting the influence of Keynes on both classic and political monetarism, arguing that, unlike earlier adherents of the quantity theory, Friedman believed that a passive monetary policy was not the appropriate policy stance during the Great Depression; Friedman famously held the Fed responsible for the depth and duration of what he called the Great Contraction, because it had allowed the US money supply to drop by a third between 1929 and 1933. This was in sharp contrast to hard-core laissez-faire opponents of Fed policy, who regarded even the mild and largely ineffectual steps taken by the Fed – increasing the monetary base by 15% – as illegitimate interventionism to obstruct the salutary liquidation of bad investments, thereby postponing the necessary reallocation of real resources to more valuable uses. So, according to DeLong, Friedman, no less than Keynes, was battling against the hard-core laissez-faire opponents of any positive action to speed recovery from the Depression. While Keynes believed that in a deep depression only fiscal policy would be effective, Friedman believed that, even in a deep depression, monetary policy would be effective. But both agreed that there was no structural reason why stimulus would necessarily counterproductive; both rejected the idea that only if the increased output generated during the recovery was of a particular composition would recovery be sustainable.

Indeed, that’s why Friedman has always been regarded with suspicion by laissez-faire dogmatists who correctly judged him to be soft in his criticism of Keynesian doctrines, never having disputed the possibility that “artificially” increasing demand – either by government spending or by money creation — in a deep depression could lead to sustainable economic growth. From the point of view of laissez-faire dogmatists that concession to Keynesianism constituted a total sellout of fundamental free-market principles.

Friedman parried such attacks on the purity of his free-market dogmatism with a counterattack against his free-market dogmatist opponents, arguing that the gold standard to which they were attached so fervently was itself inconsistent with free-market principles, because, in virtually all historical instances of the gold standard, the monetary authorities charged with overseeing or administering the gold standard retained discretionary authority allowing them to set interest rates and exercise control over the quantity of money. Because monetary authorities retained substantial discretionary latitude under the gold standard, Friedman argued that a gold standard was institutionally inadequate and incapable of constraining the behavior of the monetary authorities responsible for its operation.

The point of a gold standard, in Friedman’s view, was that it makes it costly to increase the quantity of money. That might once have been true, but advances in banking technology eventually made it easy for banks to increase the quantity of money without any increase in the quantity of gold, making inflation possible even under a gold standard. True, eventually the inflation would have to be reversed to maintain the gold standard, but that simply made alternative periods of boom and bust inevitable. Thus, the gold standard, i.e., a mere obligation to convert banknotes or deposits into gold, was an inadequate constraint on the quantity of money, and an inadequate systemic assurance of stability.

In other words, if the point of a gold standard is to prevent the quantity of money from growing excessively, then, why not just eliminate the middleman, and simply establish a monetary rule constraining the growth in the quantity of money. That was why Friedman believed that his k-percent rule – please pardon the expression – trumped the gold standard, accomplishing directly what the gold standard could not accomplish, even indirectly: a gradual steady increase in the quantity of money that would prevent monetary-induced booms and busts.

Moreover, the k-percent rule made the monetary authority responsible for one thing, and one thing alone, imposing a rule on the monetary authority prescribing the time path of a targeted instrument – the quantity of money – over which the monetary authority has direct control: the quantity of money. The belief that the monetary authority in a modern banking system has direct control over the quantity of money was, of course, an obvious mistake. That the mistake could have persisted as long as it did was the result of the analytical distraction of the money multiplier: one of the leading fallacies of twentieth-century monetary thought, a fallacy that introductory textbooks unfortunately continue even now to foist upon unsuspecting students.

The money multiplier is not a structural supply-side variable, it is a reduced-form variable incorporating both supply-side and demand-side parameters, but Friedman and other Monetarists insisted on treating it as if it were a structural — and a deep structural variable at that – supply variable, so that it no less vulnerable to the Lucas Critique than, say, the Phillips Curve. Nevertheless, for at least a decade and a half after his refutation of the structural Phillips Curve, demonstrating its dangers as a guide to policy making, Friedman continued treating the money multiplier as if it were a deep structural variable, leading to the Monetarist forecasting debacle of the 1980s when Friedman and his acolytes were confidently predicting – over and over again — the return of double-digit inflation because the quantity of money was increasing for most of the 1980s at double-digit rates.

So once the k-percent rule collapsed under an avalanche of contradictory evidence, the Monetarist alternative to the gold standard that Friedman had persuasively, though fallaciously, argued was, on strictly libertarian grounds, preferable to the gold standard, the gold standard once again became the default position of laissez-faire dogmatists. There was to be sure some consideration given to free banking as an alternative to the gold standard. In his old age, after winning the Nobel Prize, F. A. Hayek introduced a proposal for direct currency competition — the elimination of legal tender laws and the like – which he later developed into a proposal for the denationalization of money. Hayek’s proposals suggested that convertibility into a real commodity was not necessary for a non-legal tender currency to have value – a proposition which I have argued is fallacious. So Hayek can be regarded as the grandfather of crypto currencies like the bitcoin. On the other hand, advocates of free banking, with a few exceptions like Earl Thompson and me, have generally gravitated back to the gold standard.

So while I agree with DeLong and Krugman (and for that matter with his many laissez-faire dogmatist critics) that Friedman had Keynesian inclinations which, depending on his audience, he sometimes emphasized, and sometimes suppressed, the most important reason that he was unable to retain his hold on right-wing monetary-economics thinking is that his key monetary-policy proposal – the k-percent rule – was empirically demolished in a failure even more embarrassing than the stagflation failure of Keynesian economics. With the k-percent rule no longer available as an alternative, what’s a right-wing ideologue to do?

Anyone for nominal gross domestic product level targeting (or NGDPLT for short)?

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.

Sumner on the Demand for Money, Interest Rates and Barsky and Summers

Scott Sumner had two outstanding posts a couple of weeks ago (here and here) discussing the relationship between interest rates and NGDP, making a number of important points, which I largely agree with, even though I have some (mostly semantic) quibbles about the details. I especially liked how in the second post he applied the analysis of Robert Barsky and Larry Summers in their article about Gibson’s Paradox under the gold standard to recent monetary experience. The two posts are so good and cover such a wide range of topics that the best way for me to address them is by cutting and pasting relevant passages and commenting on them.

Scott begins with the equation of exchange MV = PY. I personally prefer the Cambridge version (M = kPY) where k stands for the fraction of income that people hold as cash, thereby making it clear that the relevant concept is how much money want to hold, not that mysterious metaphysical concept called the velocity of circulation V (= 1/k). With attention focused on the decision about how much money to hold, it is natural to think of the rate of interest as the opportunity cost of holding non-interest-bearing cash balances. When the rate of interest rate rises, the desired holdings of non-interest-bearing cash tend to fall; in other words k falls (and V rises). With unchanged M, the equation is satisfied only if PY increases. So the notion that a reduction in interest rates, in and of itself, is expansionary is based on a misunderstanding. An increase in the amount of money demanded is always contractionary. A reduction in interest rates increases the amount of money demanded (if money is non-interest-bearing). A reduction in interest rates is therefore contractionary (all else equal).

Scott suggests some reasons why this basic relationship seems paradoxical.

Sometimes, not always, reductions in interest rates are caused by an increase in the monetary base. (This was not the case in late 2007 and early 2008, but it is the case on some occasions.) When there is an expansionary monetary policy, specifically an exogenous increase in M, then when interest rates fall, V tends to fall by less than M rises. So the policy as a whole causes NGDP to rise, even as the specific impact of lower interest rates is to cause NGDP to fall.

To this I would add that, as discussed in my recent posts about Keynes and Fisher, Keynes in the General Theory seemed to be advancing a purely monetary theory of the rate of interest. If Keynes meant that the rate of interest is determined exclusively by monetary factors, then a falling rate of interest is a sure sign of an excess supply of money. Of course in the Hicksian world of IS-LM, the rate of interest is simultaneously determined by both equilibrium in the money market and an equilibrium rate of total spending, but Keynes seems to have had trouble with the notion that the rate of interest could be simultaneously determined by not one, but two, equilibrium conditions.

Another problem is the Keynesian model, which hopelessly confuses the transmission mechanism. Any Keynesian model with currency that says low interest rates are expansionary is flat out wrong.

But if Keynes believed that the rate of interest is exclusively determined by money demand and money supply, then the only possible cause of a low or falling interest rate is the state of the money market, the supply side of which is always under the control of the monetary authority. Or stated differently, in the Keynesian model, the money-supply function is perfectly elastic at the target rate of interest, so that the monetary authority supplies whatever amount of money is demanded at that rate of interest. I disagree with the underlying view of what determines the rate of interest, but given that theory of the rate of interest, the model is not incoherent and doesn’t confuse the transmission mechanism.

That’s probably why economists were so confused by 2008. Many people confuse aggregate demand with consumption. Thus they think low rates encourage people to “spend” and that this n somehow boosts AD and NGDP. But it doesn’t, at least not in the way they assume. If by “spend” you mean higher velocity, then yes, spending more boosts NGDP. But we’ve already seen that lower interest rates don’t boost velocity, rather they lower velocity.

But, remember that Keynes believed that the interest rate can be reduced only by increasing the quantity of money, which nullifies the contractionary effect of a reduced interest rate.

Even worse, some assume that “spending” is the same as consumption, hence if low rates encourage people to save less and consume more, then AD will rise. This is reasoning from a price change on steroids! When you don’t spend you save, and saving goes into investment, which is also part of GDP.

But this is reasoning from an accounting identity. The question is what happens if people try to save. The Keynesian argument is that the attempt to save will be self-defeating; instead of increased saving, there is reduced income. Both scenarios are consistent with the accounting identity. The question is which causal mechanism is operating? Does an attempt to increase saving cause investment to increase, or does it cause income to go down? Seemingly aware of the alternative scenario, Scott continues:

Now here’s were amateur Keynesians get hopelessly confused. They recall reading something about the paradox of thrift, about planned vs. actual saving, about the fact that an attempt to save more might depress NGDP, and that in the end people may fail to save more, and instead NGDP will fall. This is possible, but even if true it has no bearing on my claim that low rates are contractionary.

Just so. But there is not necessarily any confusion; the issue may be just a difference in how monetary policy is implemented. You can think of the monetary authority as having a choice in setting its policy in terms of the quantity of the monetary base, or in terms of an interest-rate target. Scott characterizes monetary policy in terms of the base, allowing the interest rate to adjust; Keynesians characterize monetary policy in terms of an interest-rate target, allowing the monetary base to adjust. The underlying analysis should not depend on how policy is characterized. I think that this is borne out by Scott’s next paragraph, which is consistent with a policy choice on the part of the Keynesian monetary authority to raise interest rates as needed to curb aggregate demand when aggregate demand is excessive.

To see the problem with this analysis, consider the Keynesian explanations for increases in AD. One theory is that animal spirits propel businesses to invest more. Another is that consumer optimism propels consumers to spend more. Another is that fiscal policy becomes more expansionary, boosting the budget deficit. What do all three of these shocks have in common? In all three cases the shock leads to higher interest rates. (Use the S&I diagram to show this.) Yes, in all three cases the higher interest rates boost velocity, and hence ceteris paribus (i.e. fixed monetary base) the higher V leads to more NGDP. But that’s not an example of low rates boosting AD, it’s an example of some factor boosting AD, and also raising interest rates.

In the Keynesian terminology, the shocks do lead to higher rates, but only because excessive aggregate demand, caused by animal spirits, consumer optimism, or government budget deficits, has to be curbed by interest-rate increases. The ceteris paribus assumption is ambiguous; it can be interpreted to mean holding the monetary base constant or holding the interest-rate target constant. I don’t often cite Milton Friedman as an authority, but one of his early classic papers was “The Marshallian Demand Curve” in which he pointed out that there is an ambiguity in what is held constant along the demand curve: prices of other goods or real income. You can hold only one of the two constant, not both, and you get a different demand curve depending on which ceteris paribus assumption you make. So the upshot of my commentary here is that, although Scott is right to point out that the standard reasoning about how a change in interest rates affects NGDP implicitly assumes that the quantity of money is changing, that valid point doesn’t refute the standard reasoning. There is an inherent ambiguity in specifying what is actually held constant in any ceteris paribus exercise. It’s good to make these ambiguities explicit, and there might be good reasons to prefer one ceteris paribus assumption over another, but a ceteris paribus assumption isn’t a sufficient basis for rejecting a model.

Now just to be clear, I agree with Scott that, as a matter of positive economics, the interest rate is not fully under the control of the monetary authority. And one reason that it’s not  is that the rate of interest is embedded in the entire price system, not just a particular short-term rate that the central bank may be able to control. So I don’t accept the basic Keynesian premise that monetary authority can always make the rate of interest whatever it wants it to be, though the monetary authority probably does have some control over short-term rates.

Scott also provides an analysis of the effects of interest on reserves, and he is absolutely correct to point out that paying interest on reserves is deflationary.

I will just note that near the end of his post, Scott makes a comment about living “in a Ratex world.” WADR, I don’t think that ratex is at all descriptive of reality, but I will save that discussion for another time.

Scott followed up the post about the contractionary effects of low interest rates with a post about the 1988 Barsky and Summers paper.

Barsky and Summers . . . claim that the “Gibson Paradox” is caused by the fact that low interest rates are deflationary under the gold standard, and that causation runs from falling interest rates to deflation. Note that there was no NGDP data for this period, so they use the price level rather than NGDP as their nominal indicator. But their basic argument is identical to mine.

The Gibson Paradox referred to the tendency of prices and interest rates to be highly correlated under the gold standard. Initially some people thought this was due to the Fisher effect, but it turns out that prices were roughly a random walk under the gold standard, and hence the expected rate of inflation was close to zero. So the actual correlation was between prices and both real and nominal interest rates. Nonetheless, the nominal interest rate is the key causal variable in their model, even though changes in that variable are mostly due to changes in the real interest rate.

Since gold is a durable good with a fixed price, the nominal interest rate is the opportunity cost of holding that good. A lower nominal rate tends to increase the demand for gold, for both monetary and non-monetary purposes.  And an increased demand for gold is deflationary (and also reduces NGDP.)

Very insightful on Scott’s part to see the connection between the Barsky and Summers analysis and the standard theory of the demand for money. I had previously thought about the Barsky and Summers discussion simply as a present-value problem. The present value of any durable asset, generating a given expected flow of future services, must vary inversely with the interest rate at which those future services are discounted. Since the future price level under the gold standard was expected to be roughly stable, any change in nominal interest rates implied a change in real interest rates. The value of gold, like other durable assets, varied inversely with nominal interest rate. But with the nominal value of gold fixed by the gold standard, changes in the value of gold implied a change in the price level, an increased value of gold being deflationary and a decreased value of gold inflationary. Scott rightly observes that the same idea can be expressed in the language of monetary theory by thinking of the nominal interest rate as the cost of holding any asset, so that a reduction in the nominal interest rate has to increase the demand to own assets, because reducing the cost of holding an asset increases the demand to own it, thereby raising its value in exchange, provided that current output of the asset is small relative to the total stock.

However, the present-value approach does have an advantage over the opportunity-cost approach, because the present-value approach relates the value of gold or money to the entire term structure of interest rates, while the opportunity-cost approach can only handle a single interest rate – presumably the short-term rate – that is relevant to the decision to hold money at any given moment in time. In simple models of the IS-LM ilk, the only interest rate under consideration is the short-term rate, or the term-structure is assumed to have a fixed shape so that all interest rates are equally affected by, or along with, any change in the short-term rate. The latter assumption of course is clearly unrealistic, though Keynes made it without a second thought. However, in his Century of Bank Rate, Hawtrey showed that between 1844 and 1938, when the gold standard was in effect in Britain (except 1914-25 and 1931-38) short-term rates and long-term rates often moved by significantly different magnitudes and even in opposite directions.

Scott makes a further interesting observation:

The puzzle of why the economy does poorly when interest rates fall (such as during 2007-09) is in principle just as interesting as the one Barsky and Summers looked at. Just as gold was the medium of account during the gold standard, base money is currently the medium of account. And just as causation went from falling interest rates to higher demand for gold to deflation under the gold standard, causation went from falling interest rates to higher demand for base money to recession in 2007-08.

There is something to this point, but I think Scott may be making too much of it. Falling interest rates in 2007 may have caused the demand for money to increase, but other factors were also important in causing contraction. The problem in 2008 was that the real rate of interest was falling, while the Fed, fixated on commodity (especially energy) prices, kept interest rates too high given the rapidly deteriorating economy. With expected yields from holding real assets falling, the Fed, by not cutting interest rates any further between April and October of 2008, precipitated a financial crisis once inflationary expectations started collapsing in August 2008, the expected yield from holding money dominating the expected yield from holding real assets, bringing about a pathological Fisher effect in which asset values had to collapse for the yields from holding money and from holding assets to be equalized.

Under the gold standard, the value of gold was actually sensitive to two separate interest-rate effects – one reflected in the short-term rate and one reflected in the long-term rate. The latter effect is the one focused on by Barsky and Summers, though they also performed some tests on the short-term rate. However, it was through the short-term rate that the central bank, in particular the Bank of England, the dominant central bank during in the pre-World War I era, manifested its demand for gold reserves, raising the short-term rate when it was trying to accumulate gold and reducing the short-term rate when it was willing to reduce its reserve holdings. Barsky and Summers found the long-term rate to be more highly correlated with the price level than the short-term rate. I conjecture that the reason for that result is that the long-term rate is what captures the theoretical inverse relationship between the interest rate and the value of a durable asset, while the short-term rate would be negatively correlated with the value of gold when (as is usually the case) it moves together with the long-term rate but may sometimes be positively correlated with the value of gold (when the central bank is trying to accumulate gold) and thereby tightening the world market for gold. I don’t know if Barsky and Summers ran regressions using both long-term and short-term rates, but using both long-term and short-term rates in the same regression might have allowed them to find evidence of both effects in the data.

PS I have been too busy and too distracted of late to keep up with comments on earlier posts. Sorry for not responding promptly. In case anyone is still interested, I hope to respond to comments over the next few days, and to post and respond more regularly than I have been doing for the past few weeks.

Keynes on the Theory of the Rate of Interest

I have been writing recently about Keynes and his theory of the rate of interest (here, here, here, and here). Perhaps unjustly – but perhaps not — I attribute to him a theory in which the rate of interest is determined exclusively by monetary forces: the interaction of the liquidity preference of the public with the policy of the monetary authorities. In other words, the rate of interest, at least as an approximation, can be modeled in terms of a single market for holding money, the demand to hold money reflecting the liquidity preference of the public and the stock of money being directly controlled by the monetary authority. Because liquidity preference is a function of the rate of interest, the rate of interest adjusts until the stock of money made available by the monetary authority is held willingly by the public.

I have been struggling with Keynes’s liquidity preference theory of interest, which evidently led him to deny the Fisher effect, thus denying that there is a margin of substitution between holding money and holding real assets, because he explicitly recognizes in Chapter 17 of the General Theory that there is a margin of substitution between money and real assets, the expected net returns from holding all assets (including expected appreciation and the net service flows generated by the assets) being equal in equilibrium. And it was that logic which led Keynes to one of his most important pre-General Theory contributions — the covered-interest-arbitrage theorem in chapter 3 of his Tract on Monetary Reform. The equality of expected returns on all assets was the key to Irving Fisher’s 1896 derivation of the Fisher Effect in Appreciation and Interest, restated in 1907 in The Rate of Interest, and in 1930 in The Theory of Interest.

Fisher never asserted that there is complete adjustment of nominal interest rates to expected inflation, actually providing empirical evidence that the adjustment of nominal rates to inflation was only partial, but he did show that in equilibrium a difference in the expected rate of appreciation between alternative assets must correspond to differences in the rates of interest on loans contracted in terms of the two assets. Now there is a difference between the static relationship between the interest rates for two loans contracted in terms of two different assets and a dynamic adjustment in time to a change in the expected rate of appreciation or depreciation of a given asset. The dynamic adjustment does not necessarily coincide with the static relationship.

It is also interesting, as I pointed out in a recent post, that when criticizing the orthodox theory of the rate of interest in the General Theory, Keynes focused not on Fisher, but on his teacher Alfred Marshall as the authoritative representative of the orthodox theory of interest, criticizing Fisher only for the Fisher effect. Keynes reserved is comprehensive criticism for Marshall, attributing to Marshall the notion that rate of interest adjusts to equalize savings and investment. Keynes acknowledged that he could not find textual support in Marshall’s writings for this idea, merely citing his own prior belief that the rate of interest performs that function, consequently attributing a similar belief to Marshall. But even if Marshall did mistakenly believe that the rate of interest adjusts to equalize savings and investment, it does not follow that the orthodox theory of interest is wrong; it just means that Marshall had a defective understanding of the theory. Just because most physicists in the 18th century believed in the phlogiston theory of fire does not prove that classical physics was wrong; it only means that classical physicists had an imperfect understanding of the theory. And if Keynes wanted to establish the content of the most authoritative version of the orthodox theory of interest, he should have been citing Fisher not Marshall.

That is why I wanted to have a look at a not very well known paper by Keynes called “The Theory of the Rate of Interest,” written for a 1937 festschrift in honor of Irving Fisher, The Lessons of Monetary Experience. Keynes began the paper with the following footnote attached to the title acknowledging Fisher as the outstanding authority on the orthodox theory of interest.

I have thought it suitable to offer a short note on this subject in honor of Irving Fisher, since his earliest [presumably Appreciation and Interest, Fisher’s doctoral dissertation] and latest [presumably The Theory of Interest] have been concerned with it, and since during the whole of the thirty years that I have been studying economics he has been the outstanding authority on this problem. (p. 145)

The paper is mostly devoted to spelling out and discussing six propositions that Keynes believes distill the essentials of the orthodox theory of interest. The first four of these propositions Keynes regards as unassailable, but the last two, he maintains, reflect very special, empirically false, assumptions. He therefore replaces them with two substitute propositions, whose implications differ radically from those of orthodox theory. Here are the first four propositions.

1 Interest on money means precisely what the books on arithmetic say it means. . . . [I]t is simply the premium obtainable on current cash over deferred cash, so that it measures the marginal preference . . . for holding cash in hand over cash for deferred delivery. No one would pay this premium unless the possession of cash served some purpose, i.e., has some efficiency. Thus, we can conveniently say that interest on money measures the marginal efficiency of money in terms of itself as a unit.

2 Money is not peculiar in having a marginal efficiency measured in terms of itself. . . . [N]ormally capital assets of all kinds have a positive marginal efficiency measured in terms of themselves. If we know the relation between the present and expected prices of an asset in terms of money we can convert the measure of its marginal efficiency into a measure of its marginal efficiency in terms of money by means of a formula which I have given in my General Theory, p. 227.

3 The effort to obtain the best advantage from the possession of wealth will set up a tendency for capital assets to exchange in equilibrium, at values proportional to their marginal efficiencies in terms of a common unit. . . . [I]f r is the money rate of interest . . . and y is the marginal efficiency of a capital asset A in terms of money, then A will exchange in terms of money at a price such as to make y = r.

4 If the demand price of our capital asset A . . . is not less than its replacement cost, new investment in A will take place, the scale of such investment depending on the capacity available for the production of A, i.e., on its elasticity of supply, and on the rate at which y, its marginal efficiency, declines as the amount of new investment in A increases. At a scale of new investment at which the marginal cost of producing A is equal to its demand price as above, we have a position of equilibrium. Thus the price system resulting from the relationships between the marginal efficiencies of different capital assets including money, measured in terms of a common unit, determines the aggregate rate of investment. (p. 145-46)

Keynes sums up the import of his first four propositions as follows:

These proposition are not . . . inconsistent with the orthodox theory . . . or open to doubt. They establish that relative prices . . . and the scale of output move until the marginal efficiencies of all kinds of assets are equal when measured in a common unit and . . . that the marginal efficiency of capital is equal to the rate of interest. But they tell us nothing as to the forces which determine what this common level of marginal efficiency will tend to be. It is when we proceed to this further discussion that my argument diverges from the orthodox argument.

Here is how Keynes describes the divergence between the orthodox theory and his theory:

[T]he orthodox theory maintains that the forces which determine the common value of the marginal efficiency of various assets are independent of money, which has . . . no autonomous influence, and that prices move until the marginal efficiency of money, i.e., the rate of interest, falls into line with the common value of the marginal efficiency of other assets as determined by other forces. My theory . . . maintains that this is a special case and that over a wide range of possible cases almost the opposite is true, namely, that the marginal efficiency of money is determined by forces partly appropriate to itself, and that prices move until the marginal efficiency of other assets fall into line with the rate of interest. (p. 147)

I find Keynes’s description of the difference between the orthodox theory and his own both insightful and problematic. Keynes notes correctly that the orthodox theory, abstracting from all monetary influences, treats the rate of interest as a rate of intertemporal exchange, applicable to exchange between any asset today and any asset in the future, adjusted for differences in rates of appreciation, and in net service flows, across assets. So Keynes was right: the orthodox theory is a special case, corresponding to the special assumptions required for full intertemporal equilibrium. And Keynes was right to emphasize the limitations of the orthodox theory.

But while drawing a sharp contrast between his theory and the orthodox theory (“over a wide range of possible cases almost the opposite is true”), Keynes, to qualify his disagreement, deploys the italicized (by me) weasel words, but without explaining how his seemingly flat rejection of the orthodox theory requires qualification. It is certainly reasonable to say “that the marginal efficiency of capital is determined by forces partly appropriate to itself.” But I don’t see how it follows from that premise “that prices move until the marginal efficiency of other assets fall into line with the rate of interest.” Equilibrium is reached when marginal efficiencies (adjusted for differences in expected rates of appreciation and in net services flows) of all assets are equal, but rejecting the orthodox notion that the marginal efficiency of money adjusts to the common marginal efficiency of all other assets does not establish that the causality is reversed: that the marginal efficiencies of all non-money assets must adjust to whatever the marginal efficiency of money happens to be. The reverse causality also seems like a special case; the general case, it would seem, would be one in which causality could operate, depending on circumstances, in either direction or both directions. An argument about the direction of causality would have been appropriate, but none is made. Keynes just moves on to propositions 5 and 6.

5 The marginal efficiency of money in terms of itself has the peculiarity that it is independent of its quantity. . . . This is a consequence of the Quantity Theory of Money . . . Thus, unless we import considerations from outside, the money rate of interest is indeterminate, for the demand schedule for money is a function solely of its supply [sic, presumably Keynes meant to say “quantity”]. Nevertheless, a determinate value for r can be derived from the condition that the value of an asset A, of which the marginal efficiency in terms of money is y, must be such that y = r. For provided that we know the scale of investment, we know y and the value of A, and hence we can deduce r. In other words, the rate of interest depends on the marginal efficiency of capital assets other than money. This must, however, be supplemented by another proposition; for it requires that we should already know the scale of investment. (p. 147-48)

I pause here, because I am confused. Keynes alludes to the proposition that the neutrality of money implies that any nominal interest rate is compatible with any real interest rate provided that the rate of inflation is correctly anticipated, though without articulating the proposition correctly. Despite getting off to a shaky start with a sloppy allusion to the Fisher effect, Keynes is right in observing that the neutrality of money and the independence of the real rate of interest from monetary factors are extreme assumptions. Given that monetary neutrality is consistent with any nominal interest rate, Keynes then tries to show how the orthodox theory pins down the nominal interest rate. And his attempt does not seem successful; he asserts that the money rate of interest can be deduced from the marginal efficiency of some capital asset A in terms of money. But that marginal efficiency cannot be deduced without knowledge, or an expectation, of the future value of the asset. Instead of couching his analysis in terms of the current and (expected) future values of the asset, i.e., instead of following Fisher’s 1896 own-rate analysis, Keynes brings up the scale of investment in A: “This must . . . be supplemented by another proposition; for it requires that we should already know the scale of investment.” Aside from not knowing what “this” and “it” are referring to, I don’t understand how the scale of investment is relevant to a determination of the marginal efficiency of the capital asset in question.

Now for Keynes’s final proposition:

6 The scale of investment will not reach its equilibrium level until the point is reached at which the elasticity of supply of output as a whole has fallen to zero. (p. 148)

The puzzle only deepens here because proposition 5 is referring to the scale of investment in a particular asset A while proposition 6 seems to be referring to the scale of investment in the aggregate. It is neither a necessary nor a sufficient condition for an equilibrium scale of investment in a particular capital asset to obtain that the elasticity of supply of output as a whole be zero. So the connection between propositions 5 and 6 seems tenuous and superficial. Does Keynes mean to say that, according to orthodox theory, the equality of advantage to asset holders between different kinds of assets cannot be achieved unless the elasticity of supply for output as a whole is zero? Keynes then offers a synthetic restatement of orthodox theory.

The equilibrium rate of aggregate investment, corresponding to the level of output for a further increase in which the elasticity of supply is zero, depends on the readiness of the public to save. But this in turn depends on the rate of interest. Thus for each level of the rate of interest we have a given quantity of saving. This quantity of saving determines the scale of investment. The scale of investment settles the marginal efficiency of capital, to which the rate of interest must be equal. Our system is therefore determinate. To each possible value of the rate of interest there corresponds a given volume of saving; and to each possible value of the marginal efficiency of capital there corresponds a given volume of investment. Now the rate of interest and the marginal efficiency of capital must be equal. Thus the position of equilibrium is given by that common value of the rate of interest and of the marginal efficiency of capital at which saving determined by the former is equal to the investment determined by the latter. (Id.)

This restatement of orthodox theory is remarkably disconnected from the six propositions that Keynes has just identified as the bedrock of the orthodox theory of interest. The word “saving” or “save” is not even mentioned in any of Keynes’s six propositions, so the notion that the orthodox theory asserts that the rate of interest adjusts to equalize saving and investment is inconsistent with his own rendering of the orthodox theory. The rhetorical point that Keynes seems to be making in the form of a strictly analytical discussion is that the orthodox theory held that the equilibrium of an economic system occurs at the rate of interest that equalizes savings and investment at a level of output and income consistent with full employment. Where Keynes was misguided was in characterizing the mechanism by which this equilibrium is reached as an adjustment in the nominal rate of interest. A full equilibrium is achieved by way of a vector of prices (and expected prices) consistent with equilibrium, the rate of interest being implicit in the intertemporal structure of a price vector. Keynes was working with a simplistic misconception of what the rate of interest actually represents and how it affects economic activity.

In place of propositions 5 and 6, which Keynes dismisses as special factual assumptions, he proposes two alternative propositions:

5* The marginal efficiency of money in terms of itself is . . . a function of its quantity (though not of its quantity alone), just as in the case of capital assets.

6* Aggregate investment may reach its equilibrium rate under proposition (4) above, before the elasticity of supply of output as a whole has fallen to zero. (Id.)

So in substituting 5* for 5, all Keynes did was discard a proposition that few if any economists — certainly not Fisher — upholding the orthodox theory ever would have accepted as a factual assertion. The two paragraphs that Keynes devotes to refuting proposition 5 can be safely ignored at almost zero cost. Turning to proposition 6, Keynes restates it as follows:

A zero elasticity of supply for output as a whole means that an increase of demand in terms of money will lead to no change in output; that is to say, prices will rise in the same proportion as the money demand [i.e., nominal aggregate demand, not the demand to hold money] rises. Inflation will have no effect on output or employment, but only on prices. (pp. 149-50)

So, propositions 5 and 6 turn out to be equivalent assertions that money is neutral. Having devoted two separate propositions to identify the orthodox theory of interest with the idea that money is neutral, Keynes spells out the lessons he draws from his reconstruction of the orthodox theory of the rate of interest.

If I am right, the orthodox theory is wholly inapplicable to such problems as those of unemployment and the trade cycle, or, indeed, to any of the day-to-day problems of ordinary life. Nevertheless it is often in fact applied to such problems. . . .

It leads to considerable difficulties to regard the marginal efficiency of money as wholly different in character from the marginal efficiency of other assets. Equilibrium requires . . . that the prices of different kinds of assets measured in the same unit move until their marginal efficiencies measured in that unit are equal. But if the marginal efficiency of money in terms of itself is always equal to the marginal efficiency of other assets, irrespective of the price of the latter, the whole price system in terms of money becomes indeterminate. (150-52)

Keynes is attacking a strawman here, because, even given the extreme assumptions about the neutrality of money that hardly anyone – and certainly not Fisher – accepted as factual, the equality between the marginal efficiency of money and the marginal efficiency of other assets is an equilibrium condition, not an identity, so the charge of indeterminacy is mistaken, as Keynes himself unwittingly acknowledges thereafter.

It is the elements of elasticity (a) in the desire to hold inactive balances and (b) in the supply of output as a whole, which permits a reasonable measure of stability in prices. If these elasticities are zero there is a necessity for the whole body of prices and wages to respond immediately to every change in the quantity of money. (p. 152)

So Keynes is acknowledging that the whole price system in terms of money in not indeterminate, just excessively volatile. But let’s hear him out.

This assumes a state of affairs very different from that in which we live. For the two elasticities named above are highly characteristic of the real world; and the assumption that both of them are zero assumes away three-quarters of the problems in which we are interested. (Id.)

Undoubtedly true, but neither Fisher nor most other economists who accepted the orthodox theory of the rate of interest believed either that money is always neutral or that we live in a world of perpetually full employment. Nor did Keynes show that the theoretical resources of orthodox theory were insufficient to analyze situations of less than full employment. The most obvious example of such an analysis, of course, is one in which a restrictive monetary policy, by creating an excess demand for money, raises the liquidity premium, causing the marginal efficiency of money to exceed the marginal efficiency of other assets, in which case asset prices must fall to restore the equality between the marginal efficiencies of assets and of money.

In principle, the adjustment might be relatively smooth, but if the fall of asset prices triggers bankruptcies or other forms of financial distress, and if the increase in interest rates affects spending flows, the fall in asset prices and in spending flows may become cumulative causing a general downward spiral in income and output. Such an analysis is entirely compatible with orthodox theory even if the orthodox theory, in its emphasis on equilibrium, seems very far removed from the messy dynamic adjustment associated with a sudden increase in liquidity preference.

Once Upon a Time When Keynes Endorsed the Fisher Effect

One of the great puzzles of the General Theory is Keynes’s rejection of the Fisher Effect on pp. 141-42. What is even more difficult to understand than Keynes’s criticism of the Fisher Effect, which I hope to parse in a future post, is that in his Tract on Monetary Reform Keynes had himself reproduced the Fisher Effect, though without crediting the idea to Fisher. Interestingly enough, when he turned against the Fisher Effect in the General Theory, dismissing it almost contemptuously, he explicitly attributed the idea to Fisher.

But here are a couple of quotations from the Tract in which Keynes exactly follows the Fisherian analysis. There are probably other places in which he does so as well, but these two examples seemed the most explicit. Keynes actually cites Fisher several times in the Tract, but those citations are to Fisher’s purely monetary work, in particular The Purchasing Power of Money (1911) which Keynes had reviewed in the Economic Journal. Of course, the distinction between the real and money rates of interest that Fisher made famous was not discovered by Fisher. Marshall had mentioned it and the idea was discussed at length by Henry Thornton, and possibly by other classical economists as well, so Keynes was not necessarily committing a scholarly offense by not mentioning Fisher. Nevertheless, it was Fisher who derived the relationship as a formal theorem, and the idea was already widely associated with him. And, of course, when Keynes criticized the idea, he explicitly attributed the idea to Fisher.

Economists draw an instructive distinction between what are termed the “money” rate of interest and the “real” rate of interest. If a sum of money worth 100 in terms of commodities at the time when the loan is made is lent for a year at 5 per cent interest, and is worth only 90 in terms of commodities at the end of the year, the lender receives back, including interest, what is worth only 94.5. This is expressed by saying that while the money rate of interest was 5 per cent, the real rate of interest had actually been negative and equal to minus 5.5 per cent. . . .

Thus, when prices are rising, the business man who borrows money is able to repay the lender with what, in terms of real value, not only represents no interest, but is even less than the capital originally advanced; that is the borrower reaps a corresponding benefit. It is true that , in so far as a rise in prices is foreseen, attempts to get advantage from this by increased borrowing force the money rates of interest to move upwards. It is for this reason, amongst others, that a high bank rate should be associated with a period of rising prices, and a low bank rate with a period of faling prices. The apparent abnormality of the money rate of interest at such times is merely the other side of the attempt of the real rate of interest to steady itself. Nevertheless in a period of rapidly changing prices, the money rate of interest seldom adjusts itself adequately or fast enough to prevent the real rate from becoming abnormal. For it is not the fact of a given rise of prices, but the expectation of a rise compounded of the various possible price movements and the estimated probability of each, which affects money rates. (pp. 20-22)

Like Fisher, Keynes, allowed for the possibility that inflation will not be fully anticipated so that the rise in the nominal rate will not fully compensate for the effect of inflation, suggesting that it is generally unlikely that inflation will be fully anticipated so that, in practice, inflation tends to reduce the real rate of interest. So Keynes seems fully on board with Fisher in the Tract.

Then there is Keynes’s celebrated theorem of covered interest arbitrage, perhaps his most important and enduring contribution to economics before writing the General Theory. He demonstrates the theorem in chapter 3 of the Tract.

If dollars one month forward are quoted cheaper than spot dollars to a London buyer in terms of sterling, this indicates a preference by the market, on balance, in favour of holding funds in New York during the month in question rather than in London – a preference the degree of which is measured by the discount on forward dollars. For if spot dollars are worth $4.40 to the pound and dollars one month forward $4.405 to the pound, then the owner of $4.40 can, by selling the dollars spot and buying them back one month forward, find himself at the end of the month with $4.405, merely by being during the month the owner of £1 in London instead of $4.40 in New York. That he should require and can obtain half a cent, which, earned in one month, is equal to about 1.5 per cent per annum, to induce him to do the transaction, shows, and is, under conditions of competition, a measure of, the market’s preference for holding funds during the month in question in New York rather than in London. . . .

The difference between the spot and forward rates is, therefore, precisely and exactly the measure of the preference of the money and exchange market for holding funds in one international centre rather than in another, the exchange risk apart, that is to say under conditions in which the exchange risk is covered. What is it that determines these preferences?

1. The most fundamental cause is to be found in the interest rates obtainable on “short” money – that is to say, on money lent or deposited for short periods of time in the money markets of the two centres under consideration. If by lending dollars in New York for one month the lender could earn interest at the rate of 5.5 per cent per annum, whereas by lending sterling in London for one month he could only earn interest at the rate of 4 per cent, then the preference observed above for holding funds in New York rather than London is wholly explained. That is to say, the forward quotations for the purchase of the currency of the dearer money market tend to be cheaper than spot quotations by a percentage per month equal to the excess of the interest which can be earned in a month in the dearer market over what can be earned in the cheaper. (pp. 123-34)

Compare Keynes’s discussion in the Tract to Fisher’s discussion in Appreciation and Interest, written over a quarter of a century before the Tract.

Suppose gold is to appreciate relatively to wheat a certain known amount in one year. What will be the relation between the rates of interest in the two standards? Let wheat fall in gold price (or gold rise in wheat price) so that the quantity of gold which would buy one bushel of wheat at the beginning of the year will buy 1 + a bushels at the end, a being therefore the rate of appreciation of gold in terms of wheat. Let the rate of interest in gold be i, and in wheat be j, and let the principal of the loan be D dollars or its equivalent B bushels. Our alternative contracts are then:

For D dollars borrowed D + Di or D(1 + i) dollars are due in one yr.

For B bushels     “       B + Bj or B(1 + j) bushels  ”   “    “   “   “

and our problem is to find the relation between i and j, which will make the D(1 + i) dollars equal the B(1 + j) bushels.

At first, D dollars equals B bushels.

At the end of the year D dollars equals B(1 + a) bushels

Hence at the end of one year D(1 + i) dollars equals B(1 + a) (1 + i) bushels

Since D(1 + i) dollars is the number of dollars necessary to liquidate the debt, its equivalent B(1 + a) (1 + i) bushels is the number of bushels necessary to liquidate it. But we have already designated this number of bushels by B(1 + j). Our result, therefore, is:

At the end of 1 year D(1 + i) dollars equals B(1 + j) equals B(1 + a) (1 + i) bushels

which, after B is canceled, discloses the formula:

1 + j = (1 + a) (1 + i)

Or,

j = i + a + ia

Or, in words: The rate of interest in the (relatively) depreciating standard is equal to the sum of three terms, viz., the rate of interest in the appreciating standard, the rate of appreciation itself and the product of these two elements. (pp. 8-9)

So, it’s clear that Keynes’s theorem of covered interest arbitrage in the Tract is a straightforward application of Fisher’s analysis in Appreciation and Interest. Now it is quite possible that Keynes was unaware of Fisher’s analysis in Appreciation and Interest, though it was reproduced in Fisher’s better known 1907 classic The Rate of Interest, so that Keynes’s covered-interest-arbitrage theorem may have been subjectively original, even though it had been anticipated in its essentials a quarter of a century earlier by Fisher. Nevertheless, Keynes’s failure to acknowledge, when he criticized the Fisher effect in the General Theory, how profoundly indebted he had been, in his own celebrated work on the foreign-exchange markets, to the Fisherian analysis was a serious lapse in scholarship, if not in scholarly ethics.

Thompson’s Reformulation of Macroeconomic Theory, Part V: A Neoclassical Black Hole

It’s been over three years since I posted the fourth of my four previous installments in this series about Earl Thompson’s unpublished paper “A Reformulation of Macroeconomic Theory,” Thompson’s strictly neoclassical alternative to the standard Keynesian IS-LM model. Given the long hiatus, a short recapitulation seems in order.

The first installment was an introduction summarizing Thompson’s two main criticisms of the Keynesian model: 1) the disconnect between the standard neoclassical marginal productivity theory of production and factor pricing and the Keynesian assertion that labor receives a wage equal to its marginal product, thereby implying the existence of a second scarce factor of production (capital), but with the market for capital services replaced in the IS-LM model by the Keynesian expenditure functions, creating a potential inconsistency between the IS-LM model and a deep property of neoclassical theory; 2) the market for capital services having been excluded from the IS-LM model, the model lacks a variable that equilibrates the choice between holding money or real assets, so that the Keynesian investment function is incompletely specified, the Keynesian equilibrium condition for spending – equality between savings and investment – taking no account of the incentive for capital accumulation or the relationship, explicitly discussed by Keynes, between current investment and the (expected) future price level. Excluding the dependence of the equilibrium rate of spending on (expected) inflation from the IS-LM model renders the model logically incomplete.

The second installment was a discussion of the Hicksian temporary-equilibrium method used by Thompson to rationalize the existence of involuntary unemployment. For Thompson involuntary unemployment means unemployment caused by overly optimistic expectations by workers of wage offers, leading them to mistakenly set reservation wages too high. The key idea of advantage of the temporary-equilibrium method is that it reconciles the convention of allowing a market-clearing price to equilibrate supply and demand with the phenomenon of substantial involuntary unemployment in business-cycle downturns. Because workers have an incentive to withhold their services in order to engage in further job search or job training or leisure, their actual short-run supply of labor services in a given time period is highly elastic at the expected wage. If wage offers are below expectations, workers (mistakenly = involuntarily) choose unemployment, but given those mistaken expectations, the labor market is cleared with the observed wage equilibrating the demand for labor services and supply of labor services. There are clearly problems with this way of modeling the labor market, but it does provide an analytical technique that can account for cyclical fluctuations in unemployment within a standard microeconomic framework.

In the third installment, I showed how Thompson derived his FF curve, representing combinations of price levels and interest rates consistent with (temporary) equilibrium in both factor markets (labor services and capital services) and two versions of the LM curve, representing price levels and interest rates consistent with equilibrium in the money market. The two versions of the LM curve (analogous, but not identical, to the Keynesian LM curve) correspond to different monetary regimes. In what Thompson called the classical case, the price level is fixed by convertibility of output into cash at a fixed exchange rate, with money being supplied by a competitive banking system paying competitive interest on cash balances. The LM curve in this case is vertical at the fixed price level, with any nominal rate of interest being consistent with equilibrium in the money market, inasmuch as the amount of money demanded depends not on the nominal interest rate, but on the difference between the nominal interest rate and the competitively determined interest rate paid on cash. In the modern case, cash is non-interest bearing and supplied monopolistically by the monetary authority, so the LM curve is upward-sloping, with the cost of holding cash rising with the rate of interest, thereby reducing the amount of money demanded and increasing the price level for a given quantity of money supplied by the monetary authority. The solution of the model corresponds to the intersection of the FF and LM curves. For the classical case, the intersection is unique, but in the modern case since both curves are upward sloping, multiple intersections are possible.

The focus of the fourth installment was on setting up a model analogous to the Keynesian model by replacing the market for capital services excluded by Walras’s Law with something similar to the Keynesian expenditure functions (consumption, investment, government spending, etc.). The key point is that the FF and LM curves implicitly define a corresponding CC curve (shown in Figure 4 of the third installment) with the property that, at all points on the CC curve, the excess demand for (supply of) money exactly equals the excess supply of (demand for) labor. Thus, the CC curve represents a stock equilibrium in the market for commodities (i.e., a single consumption/capital good) rather than a flow rate of expenditure and income as represented by the conventional IS curve. But the inconsistency between the upward-sloping CC curve and the downward sloping IS curve reflects the underlying inconsistency between the neoclassical and the Keynesian paradigms.

In this installment, I am going to work through Thompson’s argument about the potential for an unstable equilibrium in the version of his model with an upward-sloping LM curve corresponding to the case in which non-interest bearing money is monopolistically supplied by a central bank. Thompson makes the argument using Figure 5, a phase diagram showing the potential equilibria for such an economy in terms of the FF curve (representing price levels and nominal interest rates consistent with equilibrium in the markets for labor and capital services) and the CC curve (representing price levels and nominal interest rates consistent with equilibrium in the output market).

Thompson_Figure5A phase diagram shows the direction of price adjustment when the economy is not in equilibrium (one of the two points of intersection between the FF and the CC curves). A disequilibrium implies a price change in response to an excess supply or excess demand in some market. All points above and to the left of the FF curve correspond to an excess supply of capital services, implying a falling nominal interest rate; points below and to the right of the FF curve correspond to excess demand for capital services, implying a rising interest rate. Points above and to the left of the CC curve correspond to an excess demand for output, implying a rising price level; points below and to the right of the CC curve correspond to an excess supply of output, implying a falling price level. Points in between the FF and CC curves correspond either to an excess demand for commodities and for capital services, implying a rising price level and a rising nominal interest rate (in the region between the two points of intersection – Eu and Es — between the CC and FF curves) or to an excess supply of both capital services and commodities, implying a falling interest rate and a falling price level (in the regions below the lower intersection Eu and above the upper intersection Es). The arrows in the diagram indicate the direction in which the price level and the nominal interest rate are changing at any point in the diagram.

Given the direction of price change corresponding to points off the CC and FF curves, the upper intersection is shown to be a stable equilibrium, while the lower intersection is unstable. Moreover, the instability corresponding to the lower intersection is very dangerous, because entering the region between the CC and FF curves below Eu means getting sucked into a vicious downward spiral of prices and interest rates that can only be prevented by a policy intervention to shift the CC curve to the right, either directly by way of increased government spending or tax cuts, or indirectly, through monetary policy aimed at raising the price level and expected inflation, shifting the LM curve, and thereby the CC curve, to the right. It’s like stepping off a cliff into a black hole.

Although I have a lot of reservations about the practical relevance of this model as an analytical tool for understanding cyclical fluctuations and counter-cyclical policy, which I plan to discuss in a future post, the model does resonate with me, and it does so especially after my recent posts about the representative-agent modeling strategy in New Classical economics (here, here, and here). Representative-agent models, I argued, are inherently unable to serve as analytical tools in macroeconomics, because their reductionist approach implies that all relevant decision making can be reduced to the optimization of a single agent, insulating the analysis from any interactions between decision-makers. But it is precisely the interaction effects between decision makers that create analytical problems that constitute the subject matter of the discipline or sub-discipline known as macroeconomics. That Robert Lucas has made it his life’s work to annihilate this field of study is a sad commentary on his contribution, Nobel Prize or no Nobel Prize, as an economic theorist.

That is one reason why I regard Thompson’s model, despite its oversimplifications, as important: it is constructed on a highly aggregated, yet strictly neoclassical, foundation, including continuous market-clearing, arriving at the remarkable conclusion that not only is there an unstable equilibrium, but it is at least possible for an economy in the neighborhood of the unstable equilibrium to be caught in a vicious downward deflationary spiral in which falling prices do not restore equilibrium but, instead, suck the economy into a zero-output black hole. That result seems to me to be a major conceptual breakthrough, showing that the strict rationality assumptions of neoclassical theory can lead to aoutcome that is totally at odds with the usual presumption that the standard neoclassical assumptions inevitably generate a unique stable equilibrium and render macroeconomics superfluous.

Thinking about Interest and Irving Fisher

In two recent posts I have discussed Keynes’s theory of interest and the natural rate of interest. My goal in both posts was not to give my own view of the correct way to think about what determines interest rates,  but to identify and highlight problems with Keynes’s liquidity-preference theory of interest, and with the concept of a natural rate of interest. The main point that I wanted to make about Keynes’s liquidity-preference theory was that although Keynes thought that he was explaining – or perhaps, explicating — the rate of interest, his theory was nothing more than an explanation of why, typically, the nominal pecuniary yield on holding cash is less than the nominal yield on holding real assets, the difference in yield being attributable to the liquidity services derived from holding a maximally liquid asset rather than holding an imperfectly liquid asset. Unfortunately, Keynes imagined that by identifying and explaining the liquidity premium on cash, he had thereby explained the real yield on holding physical capital assets; he did nothing of the kind, as the marvelous exposition of the theory of own rates of interest in chapter 17 of the General Theory unwittingly demonstrates.

For expository purposes, I followed Keynes in contrasting his liquidity-preference theory with what he called the classical theory of interest, which he identified with Alfred Marshall, in which the rate of interest is supposed to be the rate that equilibrates saving and investment. I criticized Keynes for attributing this theory to Marshall rather than to Irving Fisher, which was, I am now inclined to think, a mistake on my part, because I doubt, based on a quick examination of Fisher’s two great books The Rate of Interest and The Theory of Interest, that he ever asserted that the rate of interest is determined by equilibrating savings and investment. (I actually don’t know if Marshall did or did make such an assertion.) But I think it’s clear that Fisher did not formulate his theory in terms of equating investment and savings via adjustments in the rate of interest rate. Fisher, I think, did agree (but I can’t quote a passage to this effect) that savings and investment are equal in equilibrium, but his analysis of the determination of the rate of interest was not undertaken in terms of equalizing two flows, i.e., savings and investment. Instead the analysis was carried out in terms of individual or household decisions about how much to consume out of current and expected future income, and in terms of decisions by business firms about how much available resources to devote to producing output for current consumption versus producing for future consumption. Fisher showed (in Walrasian fashion) that there are exactly enough equations in his system to solve for all the independent variables, so that his system had a solution. (That Walrasian argument of counting equations and unknowns is mathematically flawed, but later work by my cousin Abraham Wald and subsequently by Arrow, Debreu and McKenzie showed that Fisher’s claim could, under some more or less plausible assumptions, be proved in a mathematically rigorous way.)

Maybe it was Knut Wicksell who in his discussions of the determination of the rate of interest argued that the rate of interest is responsible for equalizing savings and investment, but that was not how Fisher understood what the rate of interest is all about. The Wicksellian notion that the equilibrium rate of interest equalizes savings and investment was thus a misunderstanding of the Fisherian theory, and it would be a worthwhile endeavor to trace the genesis and subsequent development of this misunderstanding to the point that Keynes and his contemporaries could have thought that they were giving an accurate representation of what orthodox theory asserted when they claimed that according to orthodox theory the rate of interest is what ensures equality between savings and investment.

This mistaken doctrine was formalized as the loanable-funds theory of interest – I believe that Dennis Robertson is usually credited with originating this term — in which savings is represented as the supply of loanable funds and investment is represented as the demand for loanable funds, with the rate of interest serving as a sort of price that is determined in Marshallian fashion by the intersection of the two schedules. Somehow it became accepted that the loanable-funds doctrine is the orthodox theory of interest determination, but it is clear from Fisher and from standard expositions of the neoclassical theory of interest which are of course simply extensions of Fisher’s work) that the loanable-funds theory is mistaken and misguided at a very basic level. (At this point, I should credit George Blackford for his comments on my post about Keynes’s theory of the rate of interest for helping me realize that it is not possible to make any sense out of the loanable-funds theory even though I am not sure that we agree on exactly why the loanable funds theory doesn’t make sense. Not that I had espoused the loanable-funds theory, but I did not fully appreciate its incoherence.)

Why do I say that the loanable-funds theory is mistaken and incoherent? Simply because it is fundamentally inconsistent with the essential properties of general-equilibrium analysis. In general-equilibrium analysis, interest rates emerge not as a separate subset of prices determined in a corresponding subset of markets; they emerge from the intertemporal relationships between and across all asset markets and asset prices. To view the rate of interest as being determined in a separate market for loanable funds as if the rate of interest were not being simultaneously determined in all asset markets is a complete misunderstanding of the theory of intertemporal general equilibrium.

Here’s how Fisher put over a century ago in The Rate of Interest:

We thus need to distinguish between interest in terms of money and interest in terms of goods. The first thought suggested by this fact is that the rate of interest in money is “nominal” and that in goods “real.” But this distinction is not sufficient, for no two forms of goods maintain or are expected to maintain, a constant price ratio toward each other. There are therefore just as many rates of interest in goods as there are forms of goods diverging in value. (p. 84, Fisher’s emphasis).

So a quarter of a century before Sraffa supposedly introduced the idea of own rates of interest in his 1932 review of Hayek’s Prices and Production, Fisher had done so in his first classic treatise on interest, which reproduced the own-rate analysis in his 1896 monograph Appreciation and Interest. While crediting Sraffa for introducing the concept of own rates of interest, Keynes, in chapter 17, simply — and brilliantly extends the basics of Fisher’s own-rate analysis, incorporating the idea of liquidity preference and silently correcting Sraffa insofar as his analysis departed from Fisher’s.

Christopher Bliss in his own classic treatise on the theory of interest, expands upon Fisher’s point.

According to equilibrium theory – according indeed to any theory of economic action which relates firms’ decisions to prospective profit and households’ decisions to budget-constrained searches for the most preferred combination of goods – it is prices which play the fundamental role. This is because prices provide the weights to be attached to the possible amendments to their net supply plans which the actors have implicitly rejected in deciding upon their choices. In an intertemporal economy it is then, naturally, present-value prices which play the fundamental role. Although this argument is mounted here on the basis of a consideration of an economy with forward markets in intertemporal equilibrium, it in no way depends on this particular foundation. As has been remarked, if forward markets are not in operation the economic actors have no choice but to substitute their “guesses” for the firm quotations of the forward markets. This will make a big difference, since full intertemporal equilibrium is not likely to be achieved unless there is a mechanism to check and correct for inconsistency in plans and expectations. But the forces that pull economic decisions one way or another are present-value prices . . . be they guesses or firm quotations. (pp. 55-56)

Changes in time preference therefore cause immediate changes in the present value prices of assets thereby causing corresponding changes in own rates of interest. Changes in own rates of interest constrain the rates of interest charged on money loans; changes in asset valuations and interest rates induce changes in production, consumption plans and the rate at which new assets are produced and capital accumulated. The notion that there is ever a separate market for loanable funds in which the rate of interest is somehow determined, and savings and investment are somehow equilibrated is simply inconsistent with the basic Fisherian theory of the rate of interest.

Just as Nick Rowe argues that there is no single market in which the exchange value of money (medium of account) is determined, because money is exchanged for goods in all markets, there can be no single market in which the rate of interest is determined because the value of every asset depends on the rate of interest at which the expected income or service-flow derived from the asset is discounted. The determination of the rate of interest can’t be confined to a single market.

The Well-Defined, but Nearly Useless, Natural Rate of Interest

Tyler Cowen recently posted a diatribe against the idea monetary policy should be conducted by setting the interest rate target of the central bank at or near the natural rate of interest. Tyler’s post elicited critical responses from Brad DeLong and Paul Krugman among others. I sympathize with Tyler’s impatience with the natural rate of interest as a guide to policy, but I think the scattershot approach he took in listing, seemingly at random, seven complaints against the natural rate of interest was not the best way to register dissatisfaction with the natural rate. Here’s Tyler’s list of seven complaints.

1 Knut Wicksell, inventor of the term “natural rate of interest,” argued that if the central bank set its target rate equal to the natural rate, it would avoid inflation and deflation and tame the business cycle. Wicksell’s argument was criticized by his friend and countryman David Davidson who pointed out that, with rising productivity, price stability would not result without monetary expansion, which would require the monetary authority to reduce its target rate of interest below the natural rate to induce enough investment to be financed by monetary expansion. Thus, when productivity is rising, setting the target rate of interest equal to the natural rate leads not to price stability, but to deflation.

2 Keynes rejected the natural rate as a criterion for monetary policy, because the natural rate is not unique. The natural rate varies with the level of income and employment.

3 Early Keynesians like Hicks, Hansen, and Modigliani rejected the natural rate as well.

4 The meaning of the natural rate has changed; it was once the rate that would result in a stable price level; now it’s the rate that results in a stable rate of inflation.

5 Friedman also rejected the natural rate because there is no guarantee that setting the target rate equal to the natural rate will result in the rate of money growth that Freidman believed was desirable.

6 Sraffa debunked the natural rate in his 1932 review of Hayek’s Prices and Production.

7 It seems implausible that the natural rate is now negative, as many exponents of the natural rate concept now claim, even though the economy is growing and the marginal productivity of capital is positive.

Let me try to tidy all this up a bit.

The first thing you need to know when thinking about the natural rate is that, like so much else in economics, you will become hopelessly confused if you don’t keep the Fisher equation, which decomposes the nominal rate of interest into the real rate of interest and the expected rate of inflation, in clear sight. Once you begin thinking about the natural rate in the context of the Fisher equation, it becomes obvious that the natural rate can be thought of coherently as either a real rate or a nominal rate, but the moment you are unclear about whether you are talking about a real natural rate or a nominal natural rate, you’re finished.

Thus, Wicksell was implicitly thinking about a situation in which expected inflation is zero so that the real and nominal natural rates coincide. If the rate of inflation is correctly expected to be zero, and the increase in productivity is also correctly expected, the increase in the quantity of money required to sustain a constant price level can be induced by the payment of interest on cash balances. Alternatively, if the payment of interest on cash balances is ruled out, the rate of capital accumulation (forced savings) could be increased sufficiently to cause the real natural interest rate under a constant price level to fall below the real natural interest rate under deflation.

In the Sraffa-Hayek episode, as Paul Zimmerman and I have shown in our paper on that topic, Sraffa failed to understand that the multiplicity of own rates of interest in a pure barter economy did not mean that there was not a unique real natural rate toward which arbitrage would force all the individual own rates to converge. At any moment, therefore, there is a unique real natural rate in a barter economy if arbitrage is operating to equalize the cost of borrowing in terms of every commodity. Moreover, even Sraffa did not dispute that, under Wicksell’s definition of the natural rate as the rate consistent with a stable price level, there is a unique natural rate. Sraffa’s quarrel was only with Hayek’s use of the natural rate, inasmuch as Hayek maintained that the natural rate did not imply a stable price level. Of course, Hayek was caught in a contradiction that Sraffa overlooked, because he identified the real natural rate with an equal nominal rate, so that he was implicitly assuming a constant expected price level even as he was arguing that the neutral monetary policy corresponding to setting the market interest rate equal to the natural rate would imply deflation when productivity was increasing.

I am inclined to be critical Milton Friedman about many aspects of his monetary thought, but one of his virtues as a monetary economist was that he consistently emphasized Fisher’s  distinction between real and nominal interest rates. The point that Friedman was making in the passage quoted by Tyler was that the monetary authority is able to peg nominal variables, prices, inflation, exchange rates, but not real variables, like employment, output, or interest rates. Even pegging the nominal natural rate is impossible, because inasmuch as the goal of targeting a nominal natural rate is to stabilize the rate of inflation, targeting the nominal natural rate also means targeting the real natural rate. But targeting the real natural rate is not possible, and trying to do so will just get you into trouble.

So Tyler should not be complaining about the change in the meaning of the natural rate; that change simply reflects the gradual penetration of the Fisher equation into the consciousness of the economics profession. We now realize that, given the real natural rate, there is, for every expected rate of inflation, a corresponding nominal natural rate.

Keynes made a very different contribution to our understanding of the natural rate. He was that there is no reason to assume that the real natural rate of interest is unique. True, at any moment there is some real natural rate toward which arbitrage is forcing all nominal rates to converge. But that real natural rate is a function of the prevailing economic conditions. Keynes believed that there are multiple equilibria, each corresponding to a different level of employment, and that associated with each of those equilibria there could be a different real natural rate. Nowadays, we are less inclined than was Keynes to call an underemployment situation an equilibrium, but there is still no reason to assume that the real natural rate that serves as an attractor for all nominal rates is independent of the state of the economy. If the real natural rate for an underperforming economy is less than the real natural rate that would be associated with the economy if it were in the neighborhood of an optimal equilibrium, there is no reason why either the real natural rate corresponding to an optimal equilibrium or the real natural rate corresponding to the current sub-optimal state of economy should be the policy rate that the monetary authority chooses as its target.

Finally, what can be said about Tyler’s point that it is implausible to suggest that the real natural rate is negative when the economy is growing (even slowly) and the marginal productivity of capital is positive? Two points.

First, the marginal productivity of gold is very close to zero. If gold is held as bullion, it is being held for expected appreciation over and above the cost of storage. So the ratio of the future price of gold to the spot price of gold should equal one plus the real rate of interest. If you look at futures prices for gold you will see that they are virtually the same as the spot price. However, storing gold is not costless. According to this article on Bloomberg.com, storage costs for gold range between 0.5 to 1% of the value of gold, implying that expected rate of return to holding gold is now less than -0.5% a year, which means that the marginal productivity of real capital is negative. Sure there are plenty of investments out there that are generating positive returns, but those are inframarginal investments. Those inframarginal investments are generating some net gain in productivity, and overall economic growth is positive, but that doesn’t mean that the return on investment at the margin is positive. At the margin, the yield on real capital seems to be negative.

If, as appears likely, our economy is underperforming, estimates of the real natural rate of interest are not necessarily an appropriate guide for the monetary authority in choosing its target rate of interest. If the aim of monetary policy is to nudge the economy onto a feasible growth path that is above the sub-optimal path along which it is currently moving, it might well be that the appropriate interest-rate target, as long as the economy remains below its optimal growth path, would be less than the natural rate corresponding to the current sub-optimal growth path.

Keynes on the Theory of Interest

In my previous post, I asserted that Keynes used the idea that savings and investment (in the aggregated) are identically equal to dismiss the neoclassical theory of interest of Irving Fisher, which was based on the idea that the interest rate equilibrates savings and investment. One of the commenters on my post, George Blackford, challenged my characterization of Keynes’s position.

I find this to be a rather odd statement for when I read Keynes I didn’t find anywhere that he argued this sort of thing. He often argued that “an act of saving” or “an act of investing” in itself could not have an direct effect on the rate of interest, and he said things like: “Assuming that the decisions to invest become effective, they must in doing so either curtail consumption or expand income”, but I don’t find him saying that savings and investment could not determine the rate of interest are identical.

A quote from Keynes in which he actually says something to this effect would be helpful here.

Now I must admit that in writing this characterization of what Keynes was doing, I was relying on my memory of how Hawtrey characterized Keynes’s theory of interest in his review of the General Theory, and did not look up the relevant passages in the General Theory. Of course, I do believe that Hawtrey’s characterization of what Keynes said to be very reliable, but it is certainly not as authoritative as a direct quotation from Keynes himself, so I have been checking up on the General Theory for the last couple of days. I actually found that Keynes’s discussion in the General Theory was less helpful than Keynes’s 1937 article “Alternative Theories of the Rate of Interest” in which Keynes responded to criticisms by Ohlin, Robertson, and Hawtrey, of his liquidity-preference theory of interest. So I will use that source rather than what seems to me to be the less direct and more disjointed exposition in the General Theory.

Let me also remark parenthetically that Keynes did not refer to Fisher at all in discussing what he called the “classical” theory of interest which he associated with Alfred Marshall, his only discussion of Fisher in the General Theory being limited to a puzzling criticism of the Fisher relation between the real and nominal rates of interest. That seems to me to be an astonishing omission, perhaps reflecting a deplorable Cambridgian provincialism or chauvinism that would not deign to acknowledge Fisher’s magisterial accomplishment in incorporating the theory of interest into the neoclassical theory of general equilibrium. Equally puzzling is that Keynes chose to refer to Marshall’s theory (which I am assuming he considered an adequate proxy for Fisher’s) as the “classical” theory while reserving the term “neo-classical” for the Austrian theory that he explicitly associates with Mises, Hayek, and Robbins.

Here is how Keynes described his liquidity-preference theory:

The liquidity-preference theory of the rate of interest which I have set forth in my General Theory of Employment, Interest and Money makes the rate of interest to depend on the present supply of money and the demand schedule for a present claim on money in terms of a deferred claim on money. This can be put briefly by saying that the rate of interest depends on the demand and supply of money. . . . (p. 241)

The theory of the rate of interest which prevailed before (let us say) 1914 regarded it as the factor which ensured equality between saving and investment. It was never suggested that saving and investment could be unequal. This idea arose (for the first time, so far as I am aware) with certain post-war theories. In maintaining the equality of saving and investment, I am, therefore, returning to old-fashioned orthodoxy. The novelty in my treatment of saving and investment consists, not in my maintaining their necessary aggregate equality, but in the proposition that it is, not the rate of interest, but the level of incomes which (in conjunction with certain other factors) ensures this equality. (pp. 248-49)

As Hawtrey and Robertson explained in their rejoinders to Keynes, the necessary equality in the “classical” system between aggregate savings and aggregate investment of which Keynes spoke was not a definitional equality but a condition of equilibrium. Plans to save and plans to invest will be consistent in equilibrium and the rate of interest – along with all the other variables in the system — must be such that the independent plans of savers and investors will be mutually consistent. Keynes had no basis for simply asserting that this consistency of plans is ensured entirely by way of adjustments in income to the exclusion of adjustments in the rate of interest. Nor did he have a basis for asserting that the adjustment to a discrepancy between planned savings and planned investment was necessarily an adjustment in income rather than an adjustment in the rate of interest. If prices adjust in response to excess demands and excess supplies in the normal fashion, it would be natural to assume that an excess of planned savings over planned investment would cause the rate of interest to fall. That’s why most economists would say that the drop in real interest rates since 2008 has been occasioned by a persistent tendency for planned savings to exceed planned investment.

Keynes then explicitly stated that his liquidity preference theory was designed to fill the theoretical gap left by his realization that a change income not in the interest rate is what equalizes savings and investment (even while insisting that savings and investment are necessarily equal by definition).

As I have said above, the initial novelty lies in my maintaining that it is not the rate of interest, but the level of incomes which ensures equality between saving and investment. The arguments which lead up to this initial conclusion are independent of my subsequent theory of the rate of interest, and in fact I reached it before I had reached the latter theory. But the result of it was to leave the rate of interest in the air. If the rate of interest is not determined by saving and investment in the same way in which price is determined by supply and demand, how is it determined? One naturally began by supposing that the rate of interest must be determined in some sense by productivity-that it was, perhaps, simply the monetary equivalent of the marginal efficiency of capital, the latter being independently fixed by physical and technical considerations in conjunction with the expected demand. It was only when this line of approach led repeatedly to what seemed to be circular reasoning, that I hit on what I now think to be the true explanation. The resulting theory, whether right or wrong, is exceedingly simple-namely, that the rate of interest on a loan of given quality and maturity has to be established at the level which, in the opinion of those who have the opportunity of choice -i.e. of wealth-holders-equalises the attractions of holding idle cash and of holding the loan. It would be true to say that this by itself does not carry us very far. But it gives us firm and intelligible ground from which to proceed. (p. 250)

Thus, Keynes denied forthrightly the notion that the rate of interest is in any way determined by the real forces of what in Fisherian terms are known as the impatience to spend income and the opportunity to invest it. However, his argument was belied by his own breathtakingly acute analysis in chapter 17 of the General Theory (“The Properties of Interest and Money”) in which, applying and revising ideas discussed by Sraffa in his 1932 review of Hayek’s Prices and Production he introduced the idea of own rates of interest.

The rate of interest (as we call it for short) is, strictly speaking, a monetary phenomenon in the special sense that it is the own-rate of interest (General Theory, p. 223) on money itself, i.e. that it equalises the advantages of holding actual cash and a deferred claim on cash. (p. 245)

The huge gap in Keynes’s reasoning here is that he neglected to say at what rate of return “the advantages of holding actual cash and a deferred claim on cash” or, for that matter, of holding any other real asset are equalized. That’s the rate of return – the real rate of interest — for which Irving Fisher provided an explanation. Keynes simply ignored — or forgot about — it, leaving the real rate of interest totally unexplained.


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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