Archive for the 'R. G. Lipsey' Category

Richard Lipsey and the Phillips Curve

Richard Lipsey has had an extraordinarily long and productive career as both an economic theorist and an empirical economist, making numerous important contributions in almost all branches of economics. (See, for example, the citation about Lipsey as a fellow of the Canadian Economics Association.) In addition, his many textbooks have been enormously influential in advocating that economists should strive to make their discipline empirically relevant by actually subjecting their theories to meaningful empirical tests in which refutation is a realistic possibility not just a sign that the researcher was insufficiently creative in theorizing or in performing the data analysis.

One of Lipsey’s most important early contributions was his 1960 paper on the Phillips Curve “The Relationship between Unemployment and the Rate of Change of Money Wages in the United Kingdom 1862-1957: A Further Analysis” in which he extended W A. Phillips’s original results, and he has continued to write about the Phillips Curve ever since. Lipsey, in line with his empiricist philosophical position, has consistently argued that a well-supported empirical relationship should not be dismissed simply because of a purely theoretical argument about how expectations are formed. In other words, the argument that adjustments in inflation expectations would cause the short-run Phillips curve relation captured by empirical estimates of the relationship between inflation and unemployment may well be valid (as was actually recognized early on by Samuelson and Solow in their famous paper suggesting that the Phillips Curve could be interpreted as a menu of alternative combinations of inflation and unemployment from which policy-makers could choose) in some general qualitative sense. But that does not mean that it had to be accepted as an undisputable axiom of economics that the long-run relationship between unemployment and inflation is necessarily vertical, as Friedman and Phelps and Lucas convinced most of the economics profession in the late 1960s and early 1970s.

A few months ago, Lipsey was kind enough to send me a draft of the paper that he presented at the annual meeting of the History of Economics Society; the paper is called “The Phillips Curve and the Tyranny of an Assumed Unique Macro Equilibrium.” Here is the abstract of the paper.

To make the argument that the behaviour of modern industrial economies since the 1990s is inconsistent with theories in which there is a unique ergodic macro equilibrium, the paper starts by reviewing both the early Keynesian theory in which there was no unique level of income to which the economy was inevitably drawn and the debate about the amount of demand pressure at which it was best of maintain the economy: high aggregate demand and some inflationary pressure or lower aggregate demand and a stable price level. It then covers the rise of the simple Phillips curve and its expectations-augmented version, which introduced into current macro theory a natural rate of unemployment (and its associated equilibrium level of national income). This rate was also a NAIRU, the only rate consistent with stable inflation. It is then argued that the current behaviour of many modern economies in which there is a credible policy to maintain a low and steady inflation rate is inconsistent with the existence of either a unique natural rate or a NAIRU but is consistent with evolutionary theory in which there is perpetual change driven by endogenous technological advance. Instead of a NAIRU evolutionary economies have a non-inflationary band of unemployment (a NAIBU) indicating a range of unemployment and income over with the inflation rate is stable. The paper concludes with the observation that the great pre-Phillips curve debates of the 1950s that assumed that there was a range within which the economy could be run with varying pressures of demand, and varying amounts of unemployment and inflationary pressure, were not as silly as they were made to seem when both Keynesian and New Classical economists accepted the assumption of a perfectly inelastic, long-run Phillips curve located at the unique equilibrium level of unemployment.

Back in January, I wrote a post about the Lucas Critique in which I pointed out that his “proof” that the Phillips Curve is vertical in his celebrated paper on econometric policy evaluation was no proof at all, but simply a very special example in which the only disequilibrium permitted in the model – a misperception of the future price level – would lead an econometrician to estimate a negatively sloped relation between inflation and employment even though under correct expectations of inflation the relationship would be vertical. Allowing for a wider range of behavioral responses, I suggested, might well change the relation between inflation and output even under correctly expected inflation. In his new paper, Lipsey correctly points out that Friedman and Phelps and Lucas, and subsequent New Classical and New Keynesian theoreticians, who have embraced the vertical Phillips Curve doctrine as an article of faith, are also assuming, based on essentially no evidence, that there is a unique macro equilibrium. But, there is very strong evidence to suggest that, in fact, any deviation from an initial equilibrium (or equilibrium time path) is likely to cause changes that, in and of themselves, cause a change in conditions that will propel the system toward a new and different equilibrium time path, rather than return to the time path the system had been moving along before it was disturbed. See my post of almost a year ago about a paper, “Does history matter?: Empirical analysis of evolutionary versus stationary equilibrium views of the economy,” by Carlaw and Lipsey.)

Lipsey concludes his paper with a quotation from his article “The Phillips Curve” published in the volume Famous Figures and Diagrams in Economics edited by Mark Blaug and Peter Lloyd.

Perhaps [then] Keynesians were too hasty in following the New Classical economists in accepting the view that follows from static [and all EWD] models that stable rates of wage and price inflation are poised on the razor’s edge of a unique NAIRU and its accompanying Y*. The alternative does not require a long term Phillips curve trade off, nor does it deny the possibility of accelerating inflations of the kind that have bedevilled many third world countries. It is merely states that industrialised economies with low expected inflation rates may be less precisely responsive than current theory assumes because they are subject to many lags and inertias, and are operating in an ever-changing and uncertain world of endogenous technological change, which has no unique long term static equilibrium. If so, the economy may not be similar to the smoothly functioning mechanical world of Newtonian mechanics but rather to the imperfectly evolving world of evolutionary biology. The Phillips relation then changes from being a precise curve to being a band within which various combinations of inflation and unemployment are possible but outside of which inflation tends to accelerate or decelerate. Perhaps then the great [pre-Phillips curve] debates of the 1940s and early 1950s that assumed that there was a range within which the economy could be run with varying pressures of demand, and varying amounts of unemployment and inflation[ary pressure], were not as silly as they were made to seem when both Keynesian and New Classical economists accepted the assumption of a perfectly inelastic, one-dimensional, long run Phillips curve located at a unique equilibrium Y* and NAIRU.”

The State We’re In

Last week, Paul Krugman, set off by this blog post, complained about the current state macroeconomics. Apparently, Krugman feels that if saltwater economists like himself were willing to accommodate the intertemporal-maximization paradigm developed by the freshwater economists, the freshwater economists ought to have reciprocated by acknowledging some role for countercyclical policy. Seeing little evidence of accommodation on the part of the freshwater economists, Krugman, evidently feeling betrayed, came to this rather harsh conclusion:

The state of macro is, in fact, rotten, and will remain so until the cult that has taken over half the field is somehow dislodged.

Besides engaging in a pretty personal attack on his fellow economists, Krugman did not present a very flattering picture of economics as a scientific discipline. What Krugman describes seems less like a search for truth than a cynical bargaining game, in which Krugman feels that his (saltwater) side, after making good faith offers of cooperation and accommodation that were seemingly accepted by the other (freshwater) side, was somehow misled into making concessions that undermined his side’s strategic position. What I found interesting was that Krugman seemed unaware that his account of the interaction between saltwater and freshwater economists was not much more flattering to the former than the latter.

Krugman’s diatribe gave Stephen Williamson an opportunity to scorn and scold Krugman for a crass misunderstanding of the progress of science. According to Williamson, modern macroeconomics has passed by out-of-touch old-timers like Krugman. Among modern macroeconomists, Williamson observes, the freshwater-saltwater distinction is no longer meaningful or relevant. Everyone is now, more or less, on the same page; differences are worked out collegially in seminars, workshops, conferences and in the top academic journals without the rancor and disrespect in which Krugman indulges himself. If you are lucky (and hard-working) enough to be part of it, macroeconomics is a great place to be. One can almost visualize the condescension and the pity oozing from Williamson’s pores for those not part of the charmed circle.

Commenting on this exchange, Noah Smith generally agreed with Williamson that modern macroeconomics is not a discipline divided against itself; the intetermporal maximizers are clearly dominant. But Noah allows himself to wonder whether this is really any cause for celebration – celebration, at any rate, by those not in the charmed circle.

So macro has not yet discovered what causes recessions, nor come anywhere close to reaching a consensus on how (or even if) we should fight them. . . .

Given this state of affairs, can we conclude that the state of macro is good? Is a field successful as long as its members aren’t divided into warring camps? Or should we require a science to give us actual answers? And if we conclude that a science isn’t giving us actual answers, what do we, the people outside the field, do? Do we demand that the people currently working in the field start producing results pronto, threatening to replace them with people who are currently relegated to the fringe? Do we keep supporting the field with money and acclaim, in the hope that we’re currently only in an interim stage, and that real answers will emerge soon enough? Do we simply conclude that the field isn’t as fruitful an area of inquiry as we thought, and quietly defund it?

All of this seems to me to be a side issue. Who cares if macroeconomists like each other or hate each other? Whether they get along or not, whether they treat each other nicely or not, is really of no great import. For example, it was largely at Milton Friedman’s urging that Harry Johnson was hired to be the resident Keynesian at Chicago. But almost as soon as Johnson arrived, he and Friedman were getting into rather unpleasant personal exchanges and arguments. And even though Johnson underwent a metamorphosis from mildly left-wing Keynesianism to moderately conservative monetarism during his nearly two decades at Chicago, his personal and professional relationship with Friedman got progressively worse. And all of that nastiness was happening while both Friedman and Johnson were becoming dominant figures in the economics profession. So what does the level of collegiality and absence of personal discord have to do with the state of a scientific or academic discipline? Not all that much, I would venture to say.

So when Scott Sumner says:

while Krugman might seem pessimistic about the state of macro, he’s a Pollyanna compared to me. I see the field of macro as being completely adrift

I agree totally. But I diagnose the problem with macro a bit differently from how Scott does. He is chiefly concerned with getting policy right, which is certainly important, inasmuch as policy, since early 2008, has, for the most part, been disastrously wrong. One did not need a theoretically sophisticated model to see that the FOMC, out of misplaced concern that inflation expectations were becoming unanchored, kept money way too tight in 2008 in the face of rising food and energy prices, even as the economy was rapidly contracting in the second and third quarters. And in the wake of the contraction in the second and third quarters and a frightening collapse and panic in the fourth quarter, it did not take a sophisticated model to understand that rapid monetary expansion was called for. That’s why Scott writes the following:

All we really know is what Milton Friedman knew, with his partial equilibrium approach. Monetary policy drives nominal variables.  And cyclical fluctuations caused by nominal shocks seem sub-optimal.  Beyond that it’s all conjecture.

Ahem, and Marshall and Wicksell and Cassel and Fisher and Keynes and Hawtrey and Robertson and Hayek and at least 25 others that I could easily name. But it’s interesting to note that, despite his Marshallian (anti-Walrasian) proclivities, it was Friedman himself who started modern macroeconomics down the fruitless path it has been following for the last 40 years when he introduced the concept of the natural rate of unemployment in his famous 1968 AEA Presidential lecture on the role of monetary policy. Friedman defined the natural rate of unemployment as:

the level [of unemployment] that would be ground out by the Walrasian system of general equilibrium equations, provided there is embedded in them the actual structural characteristics of the labor and commodity markets, including market imperfections, stochastic variability in demands and supplies, the costs of gathering information about job vacancies, and labor availabilities, the costs of mobility, and so on.

Aside from the peculiar verb choice in describing the solution of an unknown variable contained in a system of equations, what is noteworthy about his definition is that Friedman was explicitly adopting a conception of an intertemporal general equilibrium as the unique and stable solution of that system of equations, and, whether he intended to or not, appeared to be suggesting that such a concept was operationally useful as a policy benchmark. Thus, despite Friedman’s own deep skepticism about the usefulness and relevance of general-equilibrium analysis, Friedman, for whatever reasons, chose to present his natural-rate argument in the language (however stilted on his part) of the Walrasian general-equilibrium theory for which he had little use and even less sympathy.

Inspired by the powerful policy conclusions that followed from the natural-rate hypothesis, Friedman’s direct and indirect followers, most notably Robert Lucas, used that analysis to transform macroeconomics, reducing macroeconomics to the manipulation of a simplified intertemporal general-equilibrium system. Under the assumption that all economic agents could correctly forecast all future prices (aka rational expectations), all agents could be viewed as intertemporal optimizers, any observed unemployment reflecting the optimizing choices of individuals to consume leisure or to engage in non-market production. I find it inconceivable that Friedman could have been pleased with the direction taken by the economics profession at large, and especially by his own department when he departed Chicago in 1977. This is pure conjecture on my part, but Friedman’s departure upon reaching retirement age might have had something to do with his own lack of sympathy with the direction that his own department had, under Lucas’s leadership, already taken. The problem was not so much with policy, but with the whole conception of what constitutes macroeconomic analysis.

The paper by Carlaw and Lipsey, which I referenced in my previous post, provides just one of many possible lines of attack against what modern macroeconomics has become. Without in any way suggesting that their criticisms are not weighty and serious, I would just point out that there really is no basis at all for assuming that the economy can be appropriately modeled as being in a continuous, or nearly continuous, state of general equilibrium. In the absence of a complete set of markets, the Arrow-Debreu conditions for the existence of a full intertemporal equilibrium are not satisfied, and there is no market mechanism that leads, even in principle, to a general equilibrium. The rational-expectations assumption is simply a deus-ex-machina method by which to solve a simplified model, a method with no real-world counterpart. And the suggestion that rational expectations is no more than the extension, let alone a logical consequence, of the standard rationality assumptions of basic economic theory is transparently bogus. Nor is there any basis for assuming that, if a general equilibrium does exist, it is unique, and that if it is unique, it is necessarily stable. In particular, in an economy with an incomplete (in the Arrow-Debreu sense) set of markets, an equilibrium may very much depend on the expectations of agents, expectations potentially even being self-fulfilling. We actually know that in many markets, especially those characterized by network effects, equilibria are expectation-dependent. Self-fulfilling expectations may thus be a characteristic property of modern economies, but they do not necessarily produce equilibrium.

An especially pretentious conceit of the modern macroeconomics of the last 40 years is that the extreme assumptions on which it rests are the essential microfoundations without which macroeconomics lacks any scientific standing. That’s preposterous. Perfect foresight and rational expectations are assumptions required for finding the solution to a system of equations describing a general equilibrium. They are not essential properties of a system consistent with the basic rationality propositions of microeconomics. To insist that a macroeconomic theory must correspond to the extreme assumptions necessary to prove the existence of a unique stable general equilibrium is to guarantee in advance the sterility and uselessness of that theory, because the entire field of study called macroeconomics is the result of long historical experience strongly suggesting that persistent, even cumulative, deviations from general equilibrium have been routine features of economic life since at least the early 19th century. That modern macroeconomics can tell a story in which apparently large deviations from general equilibrium are not really what they seem is not evidence that such deviations don’t exist; it merely shows that modern macroeconomics has constructed a language that allows the observed data to be classified in terms consistent with a theoretical paradigm that does not allow for lapses from equilibrium. That modern macroeconomics has constructed such a language is no reason why anyone not already committed to its underlying assumptions should feel compelled to accept its validity.

In fact, the standard comparative-statics propositions of microeconomics are also based on the assumption of the existence of a unique stable general equilibrium. Those comparative-statics propositions about the signs of the derivatives of various endogenous variables (price, quantity demanded, quantity supplied, etc.) with respect to various parameters of a microeconomic model involve comparisons between equilibrium values of the relevant variables before and after the posited parametric changes. All such comparative-statics results involve a ceteris-paribus assumption, conditional on the existence of a unique stable general equilibrium which serves as the starting and ending point (after adjustment to the parameter change) of the exercise, thereby isolating the purely hypothetical effect of a parameter change. Thus, as much as macroeconomics may require microfoundations, microeconomics is no less in need of macrofoundations, i.e., the existence of a unique stable general equilibrium, absent which a comparative-statics exercise would be meaningless, because the ceteris-paribus assumption could not otherwise be maintained. To assert that macroeconomics is impossible without microfoundations is therefore to reason in a circle, the empirically relevant propositions of microeconomics being predicated on the existence of a unique stable general equilibrium. But it is precisely the putative failure of a unique stable intertemporal general equilibrium to be attained, or to serve as a powerful attractor to economic variables, that provides the rationale for the existence of a field called macroeconomics.

So I certainly agree with Krugman that the present state of macroeconomics is pretty dismal. However, his own admitted willingness (and that of his New Keynesian colleagues) to adopt a theoretical paradigm that assumes the perpetual, or near-perpetual, existence of a unique stable intertemporal equilibrium, or at most admits the possibility of a very small set of deviations from such an equilibrium, means that, by his own admission, Krugman and his saltwater colleagues also bear a share of the responsibility for the very state of macroeconomics that Krugman now deplores.

Carlaw and Lipsey on Whether History Matters

About six months ago,  I mentioned a forthcoming paper by Kenneth Carlaw and Richard Lipsey, “Does history matter? Empirical analysis  of evolutionary versus stationary equilibrium views of the economy.”  The paper was recently published in the Journal of Evolutionary Economics.  The empirical analysis undertaken by Carlaw and Lipsey undermines many widely accepted propositions of modern macroeconomics, and is thus especially timely after the recent flurry of posts on the current state of macroecoomics by Krugman, Williamson, Smith, Delong, Sumner, et al., a topic about which I may have a word or two to say anon.  Here is the abstract of the Carlaw and Lipsey paper.

The evolutionary vision in which history matters is of an evolving economy driven by bursts of technological change initiated by agents facing uncertainty and producing long term, path-dependent growth and shorter-term, non-random investment cycles. The alternative vision in which history does not matter is of a stationary, ergodic process driven by rational agents facing risk and producing stable trend growth and shorter term cycles caused by random disturbances. We use Carlaw and Lipsey’s simulation model of non-stationary, sustained growth driven by endogenous, path-dependent technological change under uncertainty to generate artificial macro data. We match these data to the New Classical stylized growth facts. The raw simulation data pass standard tests for trend and difference stationarity, exhibiting unit roots and cointegrating processes of order one. Thus, contrary to current belief, these tests do not establish that the real data are generated by a stationary process. Real data are then used to estimate time-varying NAIRU’s for six OECD countries. The estimates are shown to be highly sensitive to the time period over which they are made. They also fail to show any relation between the unemployment gap, actual unemployment minus estimated NAIRU and the acceleration of inflation. Thus there is no tendency for inflation to behave as required by the New Keynesian and earlier New Classical theory. We conclude by rejecting the existence of a well-defined a short-run, negatively sloped Philips curve, a NAIRU, a unique general equilibrium, short and long-run, a vertical long-run Phillips curve, and the long-run neutrality of money.

UPDATE:  In addition to the abstract, I think it would be worthwhile to quote the three introductory paragraphs from Carlaw and Lipsey.

Economists face two conflicting visions of the market economy, visions that reflect two distinct paradigms, the Newtonian and the Darwinian. In the former, the behaviour of the economy is seen as the result of an equilibrium reached by the operation of opposing forces – such as market demanders and suppliers or competing oligopolists – that operate in markets characterised by negative feedback that returns the economy to its static equilibrium or its stationary equilibrium growth path. In the latter, the behaviour of the economy is seen as the result of many different forces – especially technological changes – that evolve endogenously over time, that are subject to many exogenous shocks, and that often operate in markets subject to positive feedback and in which agents operate under conditions of genuine uncertainty.
One major characteristic that distinguishes the two visions is stationarity for the Newtonian and non-stationarity for the Darwinian. In the stationary equilibrium of a static general equilibrium model and the equilibrium growth path of a Solow-type or endogenous growth model, the path by which the equilibrium is reached has no effect on the equilibrium values themselves. In short, history does not matter. In contrast, an important characteristic of the Darwinian vision is path dependency: what happens now has important implications for what will happen in the future. In short, history does matter.
In this paper, we consider, and cast doubts on, the stationarity properties of models in the Newtonian tradition. These doubts, if sustained, have important implications for understanding virtually all aspects of macroeconomics, including of long term economic growth, shorter term business cycles, and stabilisation policy.
UPDATE (12/28/12):  I received an email from Richard Lipsey about this post.  He attached two footnotes (1 and 5) from his article with Carlaw, which he thinks are relevant to some of the issues raised in comments to this post.  Footnote 1 explains their use of “Darwinian” to describe their path-dependent approach to economic modeling; footnote 5 observes that the analysis of many microeconomic problems and short-run macro-policy analysis may be amenable to the static-equilibrium method.

1 The use of the terms Darwinian and Newtonian here is meant to highlight the significant difference in equilibrium concept employed in the two groups of theories that we contrast, the evolutionary and what we call equilibrium with deviations (EWD) theories. Not all evolutionary theories, including the one employed here, are strictly speaking Darwinian in the sense that they embody replication and selection. We use the term, Darwinian to highlight the critical equilibrium concept of a path dependent, non-ergodic, historical process employed in Darwinian and evolutionary theories and to draw the contrast between that and the negative feedback, usually unique, ergodic equilibrium concept employed in Newtonian and EWD theories.

 5 Most evolutionary economists accept that for many issues in micro economics, comparative static equilibrium models are useful. Also, there is nothing incompatible between the evolutionary world view and the use of Keynesian models – of which IS-LM closed by an expectations-augmented Phillips curve is the prototype – to study such short run phenomenon as stagflation and the impact effects of monetary and fiscal policy shocks. Problems arise, however, when such analyses are applied to situations in which technology is changing endogenously over time periods that are relevant to the issues being studied. Depending on the issue at hand, this might be as short as a few months.


About Me

David Glasner
Washington, DC

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

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