LARS P. SYLL

How evidence is treated in modern macroeconomics

‘New Keynesian’ macroeconomist Simon Wren-Lewis has a post on his blog discussing how evidence is treated in modern macroeconomics (emphasis added):

It is hard to get academic macroeconomists trained since the 1980s to address this question, because they have been taught that these models and techniques are fatally flawed because of the Lucas critique and identification problems. But DSGE models as a guide for policy are also fatally flawed because they are too simple. The unique property that DSGE models have is internal consistency. Take a DSGE model, and alter a few equations so that they fit the data much better, and you have what could be called a structural econometric model. It is internally inconsistent, but because it fits the data better it may be a better guide for policy.

Being able to model a credible world, a world that somehow could be considered real or similar to the real world, is not the same as investigating the real world. Even though all theories are false, since they simplify, they may still possibly serve our pursuit of truth. But then they cannot be unrealistic or false in any way. The falsehood or unrealisticness has to be qualified (in terms of resemblance, relevance, etc.). At the very least, the minimalist demand on models in terms of credibility has to give away to a stronger epistemic demand of appropriate similarity and plausibility. One could of course also ask for a sensitivity or robustness analysis, but the credible world, even after having tested it for sensitivity and robustness, can still be a far way from reality – and unfortunately often in ways we know are important. Robustness of claims in a model does not per se give a warrant for exporting the claims to real world target systems.

Questions of external validity are important more specifically also when it comes to microfounded DSGE macromodels. It can never be enough that these models somehow are regarded as internally consistent. One always also has to pose questions of consistency with the data. Internal consistency without external validity is worth nothing.

Yours truly and people like Tony Lawson have for many years been urging economists to pay attention to the ontological foundations of their assumptions and models. Sad to say, economists have not paid much attention — and so modern economics has become increasingly irrelevant to the understanding of the real world.

Within mainstream economics internal validity is still everything and external validity nothing. Why anyone should be interested in that kind of theories and models is beyond imagination. As long as mainstream economists do not come up with any export-licenses for their theories and models to the real world in which we live, they really should not be surprised if people say that this is not science, but autism!

Since fully-fledged experiments on a societal scale as a rule are prohibitively expensive, ethically indefensible or unmanageable, economic theorists have to substitute experimenting with something else. To understand and explain relations between different entities in the real economy the predominant strategy is to build models and make things happen in these “analogue-economy models” rather than engineering things happening in real economies.

Formalistic deductive “Glasperlenspiel” can be very impressive and seductive. But in the realm of science it ought to be considered of little or no value to simply make claims about the model and lose sight of reality.

Neoclassical economics has since long given up on the real world and contents itself with proving things about thought up worlds. Empirical evidence only plays a minor role in economic theory, where models largely function as a substitute for empirical evidence. Hopefully humbled by the manifest failure of its theoretical pretences, the one-sided, almost religious, insistence on axiomatic-deductivist modeling as the only scientific activity worthy of pursuing in economics will give way to methodological pluralism based on ontological considerations rather than formalistic tractability.

To have valid evidence is not enough. What economics needs is sound evidence. Why? Simply because the premises of a valid argument do not have to be true, but a sound argument, on the other hand, is not only valid, but builds on premises that are true. Aiming only for validity, without soundness, is setting the economics aspirations level too low for developing a realist and relevant science.

How true is Friedman’s permanent income hypothesis?

Noah Smith has an article up on Bloomberg View on Milton Friedman’s permanent income hypothesis (PIH). Noah argues that almost all modern macroeconomic theories are based on PIH, especially used in formulating the consumption Euler equations that make up a vital part of ‘modern’ New Classical and New Keynesian macro models.

So, what’s the problem? Well, only that PIH according to Smith is ‘most certainly wrong.’

Chris Dillow has commented on Noah’s PIH critique, arguing that although Noah is right

he overstates the newness of the evidence against the PIH. In fact, we’ve known it was flawed ever since the early 80s. He also overstates the PIH’s intellectual hegemony. The standard UK undergraduate textbook says:

“One strong prediction of the simple PIH model … is that changes in income that are predictable from past information should have no effect on current consumption. But there is by now a considerable body of work on aggregate consumption data that suggests this is wrong…This is an important result for economic policy because it suggests that changes in income as a result, say, of tax changes can have a marked effect on consumption and hence on economic activity.” (Carlin and Soskice, Macroeconomics: Imperfections, Institutions and Policies, p 221-22)”

Dillow then goes on arguing that PIH is not always wrong, that it is useful, and that it is basically all about ‘context’ and that this reinforces what Dani Rodrik has written in Economics Rules (p 5-6) :

Different social settings require different models. Economists are unlikely ever to uncover universal, general-purpose models. But in part because economists take the natural sciences as their example, they have a tendency to misuse models. They are prone to mistake a model for the model, relevant and applicable under all conditions. Economists must overcome this temptation.

Well yours truly thinks that on this issue both Noah and Chris are not critical enough.

Let me elaborate, and start with Carlin & Soskice and then move over to Rodrik and his smorgasbord view on economic models.

Wendy Carlin’s and David Soskice‘s macroeonomics textbook Macroeconomics: Institutions, Instability, and the Financial System (Oxford University Press 2015) builds more than most other intermediate macroeconomics textbooks on supplying the student with a ‘systematic way of thinking through problems’ with the help of formal-mathematical models.

They explicitly adapt a ‘New Keynesian’ framework including price rigidities and adding a financial system to the usual neoclassical macroeconomic set-up. But although I find things like the latter amendment an improvement, it’s definitely more difficult to swallow their methodological stance, and especially their non-problematized acceptance of the need for macroeconomic microfoundations.

From the first page of the book they start to elaborate their preferred 3-equations ‘New Keynesian’ macromodel. And after twenty-two pages they have already come to specifying the demand side with the help of the Permanent Income Hypothesis and its Euler equations.

But if people — not the representative agent — at least sometimes can’t help being off their labour supply curve — as in the real world — then what are these hordes of Euler equations that you find ad nauseam in these ‘New Keynesian’ macromodels gonna help us?

My doubts regarding macro economic modelers’ obsession with Euler equations is basically that, as with so many other assumptions in ‘modern’ macroeconomics, Euler equations, and the PIH that they build on, don’t fit reality.

In the standard neoclassical consumption model — underpinning Carlin’s and Soskice’s microfounded macroeconomic modeling — people are basically portrayed as treating time as a dichotomous phenomenon – today and the future — when contemplating making decisions and acting. How much should one consume today and how much in the future? The Euler equation used implies that the representative agent (consumer) is indifferent between consuming one more unit today or instead consuming it tomorrow. Further, in the Euler equation we only have one interest rate, equated to the money market rate as set by the central bank. The crux is, however, that — given almost any specification of the utility function – the two rates are actually often found to be strongly negatively correlated in the empirical literature!

From a methodological pespective yours truly has to conclude that Carlin’s and Soskice’s microfounded macroeconomic model is a rather unimpressive attempt at legitimizing using fictitious idealizations — such as PIH and Euler equations — for reasons more to do with model tractability than with a genuine interest of understanding and explaining features of real economies.

Re Dani Rodrik‘s Economics Rules, there sure is much in the book I like and appreciate.But there is also a very disturbing apologetic tendency in the book to blame all of the shortcomings on the economists and depicting economics itself as a problem-free smorgasbord collection of models. If you just choose the appropriate model from the immense and varied smorgasbord there’s no problem. It is as if all problems in economics were conjured away if only we could make the proper model selection.

Underlying Rodrik and other mainstream economists views on models is a picturing of models as some kind of experiments. I’ve run into that view many times over the years when having discussions with mainstream economists on their ‘thought experimental’ obsession — and I still think it’s too vague and elusive to be helpful. Just repeating the view doesn’t provide the slightest reasont to believe it.

Limiting model assumptions in economic science always have to be closely examined since if we are going to be able to show that the mechanisms or causes that we isolate and handle in our models are stable in the sense that they do not change when we ‘export’ them to our ‘target systems,’ we have to be able to show that they do not only hold under ceteris paribus conditions and hence only are of limited value to our understanding, explanations or predictions of real economic systems.

Mainstream economists usually do not want to get hung up on the assumptions that their models build on. But it is still an undeniable fact that theoretical models building on piles of known to be false assumptions — such as PIH and the Euler equations that build on it — in no way even get close to being scientific explanations. On the contrary. They are untestable and hence totally worthless from the point of view of scientific relevance.

Conclusion: mainstream macroeconomics, building on the standard neoclassical consumption model with its Permanent Income Hypothesis and Euler equations, has to be replaced with something else. Preferably with something that is both real and relevant, and not only chosen for reasons of mathematical tractability.

Gary Becker’s big mistake

The econometrician Henri Theil once said “models are to be used but not to be believed.” I use the rational actor model for thinking about marginal changes but Gary Becker really believed the model. Once, at a dinner with Becker, I remarked that extreme punishment could lead to so much poverty and hatred that it could create blowback. Becker was having none of it. For every example that I raised of blowback, he responded with a demand for yet more punishment …

You can see the idea in his great paper, Crime and Punishment: An Economic Approach. In a famous section he argues that an optimal punishment system would combine a low probability of being punished with a high level of punishment if caught …

We have now tried that experiment and it didn’t work … Most spectacularly, the experiment with greater punishment led to more spending on crime control and many more people in prison …

In the economic theory, crime is in a criminal’s interest … But is crime always done out of interest? The rational actor model fits burglary, pick-pocketing and insider trading but lots of crime–including vandalism, arson, bar fights and many assaults–aren’t motivated by economic gain and perhaps not by any rational interest …

The rational choice theory was pushed beyond its limits and in so doing not only was punishment pushed too far we also lost sight of alternative policies that could reduce crime without the social disruption and injustice caused by mass incarceration.

Alex Tabarrok

Interesting article, but although Becker’s belief in his model being a real picture of reality is rather gobsmacking, I’m far from convinced by Tabarrok’s instrumentalist use of the same kind of models.

The alarm that sets off in my brain when reading Becker is that ‘rational actor models,’ rather than being helpful for understanding real world economic issues, sounds more like an ill-advised plaidoyer for voluntarily taking on a methodological straight-jacket of unsubstantiated and known to be false assumptions.

The assumptions that Becker’s theory builds on are, as Tabarrok and almost all empirical testing of it has shown, totally unrealistic. That is, they are empirically false.

That said, one could indeed wonder why on earth anyone should be interested in applying that kind of theory to real world situations. As so many other mainstream mathematical models taught to economics students today, it has next to nothing to do  with the real world.

From a methodological point of view one can, of course, also wonder, how we are supposed to evaluate tests of a theories and models building on known to be false assumptions. What is the point of such tests? What can those tests possibly teach us? From falsehoods anything logically follows.

Modern expected utility theory is a good example of this. Leaving the specification of preferences without almost any restrictions whatsoever, every imaginable evidence is safely made compatible with the all-embracing ‘theory’ — and a theory without informational content never risks being empirically tested and found falsified. Used in mainstream economics ‘thought experimental’ activities, it may of course be very ‘handy’, but totally void of any empirical value.

Utility theory has like so many other economic theories morphed into an empty theory of everything. And a theory of everything explains nothing — just as Gary Becker’s ‘economics of everything’ it only makes nonsense out of economic science.

Using false assumptions, mainstream modelers can derive whatever conclusions they want. Wanting to show that ‘all economists consider austerity to be the right policy,’ just e.g. assume ‘all economists are from Chicago’ and ‘all economists from Chicago consider austerity to be the right policy.’  The conclusions follows by deduction — but is of course factually totally wrong. Models and theories building on that kind of reasoning is nothing but a pointless waste of time — of which Gary Becker’s ‘rational actor model’ is a superb example.

Austerity policies — nothing but kindergarten economics

I definitely recommend everyone to watch this well-argued interview with Steve Keen.

To many conservative and neoliberal politicians and economists there seems to be a spectre haunting the United States and Europe today — Keynesian ideas on governments pursuing policies raising effective demand and supporting employment. And some of the favourite arguments used among these Keynesophobics to fight it are the confidence argument and the doctrine of ‘sound finance.’

Is this witless crusade against economic reason new? Not at all!

It should be first stated that, although most economists are now agreed that full employment may be achieved by government spending, this was by no means the case even in the recent past. Among the opposers of this doctrine there were (and still are) prominent so-called ‘economic experts’ closely connected with banking and industry. This suggests that there is a political background in the opposition to the full employment doctrine, even though the arguments advanced are economic. That is not to say that people who advance them do not believe in their economics, poor though this is. But obstinate ignorance is usually a manifestation of underlying political motives …

Clearly, higher output and employment benefit not only workers but entrepreneurs as well, because the latter’s profits rise. And the policy of full employment outlined above does not encroach upon profits because it does not involve any additional taxation. The entrepreneurs in the slump are longing for a boom; why do they not gladly accept the synthetic boom which the government is able to offer them? It is this difficult and fascinating question with which we intend to deal in this article …

We shall deal first with the reluctance of the ‘captains of industry’ to accept government intervention in the matter of employment. Every widening of state activity is looked upon by business with suspicion, but the creation of employment by government spending has a special aspect which makes the opposition particularly intense. Under a laissez-faire system the level of employment depends to a great extent on the so-called state of confidence. If this deteriorates, private investment declines, which results in a fall of output and employment (both directly and through the secondary effect of the fall in incomes upon consumption and investment). This gives the capitalists a powerful indirect control over government policy: everything which may shake the state of confidence must be carefully avoided because it would cause an economic crisis. But once the government learns the trick of increasing employment by its own purchases, this powerful controlling device loses its effectiveness. Hence budget deficits necessary to carry out government intervention must be regarded as perilous. The social function of the doctrine of ‘sound finance’ is to make the level of employment dependent on the state of confidence.

Michal Kalecki Political aspects of full employment  (1943)

Lucas-Rapping and ‘New Keynesian’ models of unemployment

Lucas and Rapping (1969) claim that cyclical increases in unemployment occur when workers quit their jobs because wages or salaries fall below expectations …

According to this explanation, when wages are unusually low, people become unemployed in order to enjoy free time, substituting leisure for income at a time when they lose the least income …

According to the theory, quits into unemployment increase during recessions, whereas historically quits decrease sharply and roughly half of unremployed workers become jobless because they are laid off … During the recession I studied, people were even afraid to change jobs because new ones might prove unstable and lead to unemployment …

If wages and salaries hardly ever fall, the intertemporal substitution theory is widely applicable only if the unemployed prefer jobless leisure to continued employment at their old pay. However, the attitude and circumstances of the unemployed are not consistent with their having made this choice …

In real business cycle theory, unemployment is interpreted as leisure optimally selected by workers, as in the Lucas-Rapping model. It has proved difficult to construct business cycle models consistent with this assumption and with real wage fluctuations as small as they are in reality, relative to fluctuations in employment.

Truman F. Bewley

This is, of course, only what you would expect of New Classical Chicago economists.

But sadly enough this extraterrestial view of unemployment is actually shared by so called New Keynesians, whose microfounded dynamic stochastic general equilibrium models cannot even incorporate such a basic fact of reality as involuntary unemployment!

Of course, working with microfunded representative agent models, this should come as no surprise. If one representative agent is employed, all representative agents are. The kind of unemployment that occurs is voluntary, since it is only adjustments of the hours of work that these optimizing agents make to maximize their utility. In this model world, unemployment is always an optimal choice to changes in the labour market conditions. Hence, unemployment is totally voluntary. To be unemployed is something one optimally chooses to be.

If substantive questions about the real world are being posed, it is the formalistic-mathematical representations utilized to analyze them that have to match reality, not the other way around.

To Keynes this was self-evident. But obviously not so to New Classical and ‘New Keynesian’ economists.

New Keynesian unemployment — a paid vacation essentially!

Franco Modigliani famously quipped that he did not think that unemployment during the Great Depression should be described, in an economic model, as a “sudden bout of contagious laziness”. Quite. For the past thirty years we have been debating whether to use classical real business cycle models (RBC), or their close cousins, modern New Keynesian (NK) models, to describe recessions. In both of these models, the social cost of persistent unemployment is less than a half a percentage point of steady state consumption.

What does that mean? Median US consumption is roughly $30,000 a year. One half of one percent of this is roughly 50 cents a day. A person inhabiting one of our artificial model RBC or NK model worlds, would not be willing to pay more than 50 cents a day to avoid another Great Depression. That is true of real business cycle models. It is also true of New Keynesian models …

That’s why I eschew NK and RBC models. They are both wrong. The high unemployment that follows a financial crisis is not the socially efficient response to technology shocks. And the slow recovery from a financial melt-down has nothing to do with the costs of reprinting menus that underpins the models of NK economists. It is a potentially permanent failure of private agents to coordinate on an outcome that is socially desirable.

Roger Farmer

In the basic DSGE models used by both New Classical and ‘New Keynesian’ macroeconomists, the labour market is always cleared – responding to a changing interest rate, expected life time incomes, or real wages, the representative agent maximizes the utility function by varying her labour supply, money holding and consumption over time. Most importantly – if the real wage somehow deviates from its ‘equilibrium value,’ the representative agent adjust her labour supply, so that when the real wage is higher than its ‘equilibrium value,’ labour supply is increased, and when the real wage is below its ‘equilibrium value,’ labour supply is decreased.

In this model world, unemployment is always an optimal choice to changes in the labour market conditions. Hence, unemployment is totally voluntary. To be unemployed is something one optimally chooses to be — a kind of prolonged vacation.

Although this picture of unemployment as a kind of self-chosen optimality, strikes most people as utterly ridiculous, there are also, unfortunately, a lot of neoclassical economists out there who still think that price and wage rigidities are the prime movers behind unemployment. DSGE models basically explains variations in employment (and a fortiori output) with assuming nominal wages being more flexible than prices – disregarding the lack of empirical evidence for this rather counterintuitive assumption.

Lowering nominal wages would not  clear the labour market. Lowering wages – and possibly prices – could, perhaps, lower interest rates and increase investment. It would be much easier to achieve that effect by increasing the money supply. In any case, wage reductions was not seen as a general substitute for an expansionary monetary or fiscal policy. And even if potentially positive impacts of lowering wages exist, there are also more heavily weighing negative impacts – management-union relations deteriorating, expectations of on-going lowering of wages causing delay of investments, debt deflation et cetera.

The classical proposition that lowering wages would lower unemployment and ultimately take economies out of depressions, was ill-founded and basically wrong. Flexible wages would probably only make things worse by leading to erratic price-fluctuations. The basic explanation for unemployment is insufficient aggregate demand, and that is mostly determined outside the labour market.

Obviously it’s rather embarrassing that the kind of DSGE models ‘modern’ macroeconomists use cannot incorporate such a basic fact of reality as involuntary unemployment. Of course, working with representative agent models, this should come as no surprise. The kind of unemployment that occurs is voluntary, since it is only adjustments of the hours of work that these optimizing agents make to maximize their utility.

And as if this is nonsense economics is not enough, in New Classical and ‘New Keynesian’ macroeconomists DSGE models increases in government spending leads to a drop in private consumption!

How on earth does one arrive at such as bizarre view?

In the most basic mainstream proto-DSGE models one often assumes that governments finance current expenditures with current tax revenues.  This will have a negative income effect on the households, leading — rather counterintuitively — to a drop in private consumption although both employment an production expands. This mechanism also holds when the (in)famous Ricardian equivalence is added to the models.

Ricardian equivalence basically means that financing government expenditures through taxes or debts is equivalent, since debt financing must be repaid with interest, and agents — equipped with rational expectations — would only increase savings in order to be able to pay the higher taxes in the future, thus leaving total expenditures unchanged.

Why?

In the standard neoclassical consumption model — used in DSGE macroeconomic modeling — people are basically portrayed as treating time as a dichotomous phenomenon – today and the future — when contemplating making decisions and acting. How much should one consume today and how much in the future? Facing an intertemporal budget constraint of the form

c_t + c_f/(1+r) = f_t + y_t + y_f/(1+r),

where c_t is consumption today, c_f is consumption in the future, f_t is holdings of financial assets today, y_t is labour incomes today, y_f is labour incomes in the future, and r is the real interest rate, and having a lifetime utility function of the form

U = u(c_t) + au(c_f),

where a is the time discounting parameter, the representative agent (consumer) maximizes his utility when

u'(c_t) = a(1+r)u'(c_f).

This expression – the Euler equation – implies that the representative agent (consumer) is indifferent between consuming one more unit today or instead consuming it tomorrow. Typically using a logarithmic function form – u(c) = log c – which gives u'(c) = 1/c, the Euler equation can be rewritten as

1/c_t = a(1+r)(1/c_f),

or

c_f/c_t = a(1+r).

This importantly implies that according to the neoclassical consumption model changes in the (real) interest rate and consumption move in the same direction. And — it also follows that consumption is invariant to the timing of taxes, since wealth — f_t + y_t + y_f/(1+r) — has to be interpreted as present discounted value net of taxes. And so, according to the assumption of Ricardian equivalence, the timing of taxes does not affect consumption, simply because the maximization problem as specified in the model is unchanged. As a result — households cut down on their consumption when governments increase their spendings. Mirabile dictu!

Macroeconomic models have to abandon Ricardian equivalence nonsense. But replacing it with “overlapping generations” and “infinite-horizon” models — is– in terms of realism and relevance — just getting out of the frying pan into the fire. All unemployment is still voluntary. Intertemporal substitution between labour and leisure is still ubiquitous. And the specification of the utility function is still hopelessly off the mark from an empirical point of view.

As one Nobel laureate had it:

Ricardian equivalence is taught in every graduate school in the country. It is also sheer nonsense.

Joseph E. Stiglitz, twitter 

And as one economics blogger has it:

New Classical and ‘New Keynesian’ DSGE modeling is taught in every graduate school in the country. It is also sheer nonsense.

Lars P Syll, twitter 

Economics vs. reality

Denicolò and Zanchettin, in an article published by the prestigious Economic Journal, claim to have shown among other things that “stronger patent protection may reduce innovation and growth.” As a prelude to forty pages of mathematics, they state of their model, “The economy is populated by L identical, infinitely lived, individuals … There is a unique final good in the economy that can be consumed, used to produce intermediate goods, or used in research …” Not only are all the people in this model world identical and immortal, they only produce a single product. The product has properties that are entirely unreal—not so much science fiction as pure magic. The conclusion may be justified, or not; but the idea that a model so remote from reality can be used to make public policy recommendations is, to anyone but a fully certified neoclassical economist, staggering.

The mathematization of economics since WW II has made mainstream — neoclassical — economists more or less obsessed with formal, deductive-axiomatic models. Confronted with the critique that they do not solve real problems, they  often react as Saint-Exupéry‘s Great Geographer, who, in response to the questions posed by The Little Prince, says that he is too occupied with his scientific work to be be able to say anything about reality. Confronting economic theory’s lack of relevance and ability to tackle real probems, one retreats into the wonderful world of economic models. One goes in to the “shack of tools” — as my old mentor Erik Dahmén used to say — and stays there. While the economic problems in the world around us steadily increase, one is rather happily playing along with the latest toys in the mathematical toolbox.

Modern mainstream economics is sure very rigorous — but if it’s rigorously wrong, who cares?

Instead of making formal logical argumentation based on deductive-axiomatic models the message, I think we are better served by economists who more  than anything else try to contribute to solving real problems. And then the motto of John Maynard Keynes is more valid than ever:

It is better to be vaguely right than precisely wrong