LARS P. SYLL

Macroeconomics and the Friedman-Savage ‘as if’ logic

An objection to the hypothesis just presented that is likely to be raised by many … is that it conflicts with the way human beings actually behave and choose. … Is it not patently unrealistic to suppose that individuals … base their decision on the size of the
expected utility?

While entirely natural and under-
standable, this objection is not strictly relevant … The hypothesis asserts rather that, in making a particular class of decisions, individuals behave as if they calculated and compared expected utility and as if they knew the odds. The validity of this assertion … depend  solely on whether it yields sufficiently accurate predictions about the class of decisions
with which the hypothesis deals.

M Friedman & L J Savage

‘Modern’ macroeconomics — Dynamic Stochastic General Equilibrium, New Synthesis, New Classical and New ‘Keynesian’ — still follows the Friedman-Savage ‘as if’ logic of denying the existence of genuine uncertainty and treat variables as if drawn from a known ‘data-generating process’ with a known probability distribution that unfolds over time and on which we, therefore, have access to heaps of historical time-series. If we do not assume that we know the ‘data-generating process’ – if we do not have the ‘true’ model – the whole edifice collapses. And of course, it has to. Who really honestly believes that we have access to this mythical Holy Grail, the data-generating process?

‘Modern’ macroeconomics obviously did not anticipate the enormity of the problems that unregulated ‘efficient’ financial markets created. Why? Because it builds on the myth of us knowing the ‘data-generating process’ and that we can describe the variables of our evolving economies as drawn from an urn containing stochastic probability functions with known means and variances.

This is like saying that you are going on a holiday trip and that you know that the chance of the weather being sunny is at least 30​% and that this is enough for you to decide on bringing along your sunglasses or not. You are supposed to be able to calculate the expected utility based on the given probability of sunny weather and make a simple decision of either or. Uncertainty is reduced to risk.

But as Keynes convincingly argued in his monumental Treatise on Probability (1921), this is not always possible. Often we simply do not know. According to one model, the chance of sunny weather is perhaps somewhere around 10% and according to another — equally good — model the chance is perhaps somewhere around 40%. We cannot put exact numbers on these assessments. We cannot calculate means and variances. There are no given probability distributions that we can appeal to.

In the end,​ this is what it all boils down to. We all know that many activities, relations, processes, and events are of the Keynesian uncertainty type. The data do not unequivocally single out one decision as the only ‘rational’ one. Neither the economist nor the deciding individual can fully pre-specify how people will decide when facing uncertainties and ambiguities that are ontological facts of the way the world works.

Some macroeconomists, however, still want to be able to use their hammer. So they — like Friedman and Savage — decide to pretend that the world looks like a nail, and pretend that uncertainty can be reduced to risk. So they construct their mathematical models on that assumption. The result: financial crises and economic havoc.

How much better — how much bigger chance that we do not lull us into the comforting thought that we know everything and that everything is measurable and we have everything under control — if instead, we could just admit that we often simply do not know and that we have to live with that uncertainty as well as it goes.

Fooling people into believing that one can cope with an unknown economic future in a way similar to playing the roulette wheels, is a sure recipe for only one thing — economic catastrophe!

What’s the use of economics?

The simple question that was raised during a recent conference … was to what extent has — or should — the teaching of economics be modified … The simple answer is that the economics profession is unlikely to change. Why would economists be willing to give up much of their human capital, painstakingly nurtured for over two centuries? For macroeconomists in particular, the reaction has been to suggest that modifications of existing models to take account of ‘frictions’ or ‘imperfections’ will be enough to account for the current evolution of the world economy. The idea is that once students have understood the basics, they can be introduced to these modifications …

I would go further; rather than making steady progress towards explaining economic phenomena professional economists have been locked into a narrow vision of the economy. We constantly make more and more sophisticated models within that vision until, as Bob Solow put it, “the uninitiated peasant is left wondering what planet he or she is on” …

Every student in economics is faced with the model of the isolated optimising individual who makes his choices within the constraints imposed by the market. Somehow, the axioms of rationality imposed on this individual are not very convincing, particularly to first-time students. But the student is told that the aim of the exercise is to show that there is an equilibrium, there can be prices that will clear all markets simultaneously. And, furthermore, the student is taught that such an equilibrium has desirable welfare properties. Importantly, the student is told that since the 1970s it has been known that whilst such a system of equilibrium prices may exist, we cannot show that the economy would ever reach an equilibrium nor that such an equilibrium is unique.

The student then moves on to macroeconomics and is told that the aggregate economy or market behaves just like the average individual she has just studied. She is not told that these general models in fact poorly reflect reality. For the macroeconomist, this is a boon since he can now analyse the aggregate allocations in an economy as though they were the result of the rational choices made by one individual. The student may find this even more difficult to swallow when she is aware that peoples’ preferences, choices and forecasts are often influenced by those of the other participants in the economy. Students take a long time to accept the idea that the economy’s choices can be assimilated to those of one individual.

Alan Kirman What’s the use of economics?

An economic theory that does not go beyond proving theorems and conditional ‘if-then’ statements — and does not make assertions and put forward hypotheses about real-world individuals and institutions — is of little consequence for anyone wanting to use theories to better understand, explain or predict real-world phenomena.

Building theories and models on patently ridiculous assumptions we know people never conform to, does not deliver real science. Real and reasonable people have no reason to believe in ‘as-if’ models of ‘rational’ robot imitations acting and deciding in a Walt Disney world characterised by ‘common knowledge,’ ‘full information,’ ‘rational expectations,’ zero transaction costs, given stochastic probability distributions, risk-reduced genuine uncertainty, and other laughable nonsense assumptions of the same ilk. Science fiction is not science.

For decades now, economics students have been complaining about the way economics is taught. Their complaints are justified. Force-feeding young and open-minded people with unverified and useless theories and models cannot be the right way to develop a relevant and realist economic science.

Much work done in mainstream theoretical economics is devoid of any explanatory interest. And not only that. Seen from a strictly scientific point of view, it has no value at all. It is a waste of time. And as so many have been experiencing in modern times of austerity policies and market fundamentalism — a very harmful waste of time.

Alan Kirman presents a forceful critique of mainstream economics in general, and more specifically, of the kind of assumptions that mainstream macroeconomic modelling is built on. For most heterodox critics of mainstream economics, the themes are probably well-known. But although Kirman and his collaborators’ alternative agent-based models in many ways are superior to the more traditional mainstream ‘Walt Disney’ kind of models, yours truly is not convinced that their unquestioned attachment to mathematical-formalist modelling is the right way to move forward in making economics a more realist and relevant science.