LARS P. SYLL

Tio trasiga teorier om ekonomi

Under ett par decennier har jag undersökt företagsvärlden och samhällsekonomins många olika uttryck och avarter. Men det har hela tiden varit något som skavt …

Tänk om det var något med själva kartan. Själva teorin och modellen … Snabbt blev det uppenbart för mig att många av teorierna och modellerna bakom den dominerande ekonomiska politiken inte alls var så objektiva, vetenskapligt robusta och okontro-versiella som de ofta presenters som. Inte heller verkar nationalekonomin stå så frikopplad från det politiska som man kan förledas att tro.

En klart läsvärd (med undantag för kapitlet om Pikettys “miss”) kritik av mycket som är galet inom dagens nationalekonomi.

It’s time to tax the Wall Street casino!

Speculators may do no harm as bubbles on a steady stream of enterprise. But the position is serious when enterprise becomes the bubble on a whirlpool of speculation. When the capital development of a country becomes a by-product of the activities of a casino, the job is likely to be ill-done.The measure of success attained by Wall Street, regarded as an institution of which the proper social purpose is to direct new investment into the most profitable channels in terms of future yield, cannot be claimed as one of the outstanding triumphs of laissez-faire capitalism — which is not surprising, if I am right in thinking that the best brains of Wall Street have been in fact directed towards a different object.

These tendencies are a scarcely avoidable outcome of our having successfully organised “liquid” investment markets. It is usually agreed that casinos should, in the public interest, be inaccessible and expensive. And perhaps the same is true of Stock Exchanges … The introduction of a substantial Government transfer tax on all transactions might prove the most serviceable reform available, with a view to mitigating the predominance of speculation over enterprise in the United States.

Non-ergodic stationarity (wonkish)

Let’s say we have a stationary process. That does not guarantee that it is also ergodic. The long-run time average of a single output function of the stationary process may not converge to the expectation of the corresponding variables — and so the long-run time average may not equal the probabilistic (expectational) average. Say we have two coins, where coin A has a probability of 1/2 of coming up heads, and coin B has a probability of 1/4 of coming up heads. We pick either of these coins with a probability of 1/2 and then toss the chosen coin over and over again. Now let H1, H2, … be either one or zero as the coin comes up heads or tales. This process is obviously stationary, but the time averages — [H1 + … + Hn]/n — converges to 1/2 if coin A is chosen, and 1/4 if coin B is chosen. Both these time averages have a probability of 1/2 and so their expectational average is 1/2 x 1/2 + 1/2 x 1/4 = 3/8, which obviously is not equal to 1/2 or 1/4. The time averages depend on which coin you happen to choose, while the probabilistic (expectational) average is calculated for the whole “system” consisting of both coin A and coin B.

The laws of mathematics and economics

Some commentators on this blog — and elsewhere — seem to have problems with yours truly’s critique of the overly debonair attitude with which mathematics is applied to economics. In case you think the critique is some odd outcome of heterodox idiosyncrasy, well, maybe you should think twice …

Taylor series (student stuff)

Mainstream economics — an emperor turned out to be naked

The main reason why the teaching of microeconomics (or of “ micro foundations” of macroeconomics) has been called “autistic” is because it is increasingly impossible to discuss real-world economic questions with microeconomists – and with almost all neoclassical theorists. They are trapped in their system, and don’t in fact care about the outside world any more. If you consult any microeconomic textbook, it is full of maths (e.g. Kreps or Mas-Colell, Whinston and Green) or of “tales” (e.g. Varian or Schotter), without real data (occasionally you find “examples”, or “applications”, with numerical examples – but they are purely fictitious, invented by the authors).

At first, French students got quite a lot of support from teachers and professors: hundreds of teachers signed petitions backing their movement – specially pleading for “pluralism” in teaching the different ways of approaching economics. But when the students proposed a precise program of studies … almost all teachers refused, considering that is was “too much” because “students must learn all these things, even with some mathematical details”. When you ask them “why?”, the answer usually goes something like this: “Well, even if we, personally, never use the kind of ‘theory’ or ‘tools’ taught in micoreconomics Courses … surely there are people who do ‘use’ and ‘apply’ them, even if it is in an ‘unrealistic’, or ‘excessive’ way”.

But when you ask those scholars who do “use these tools”, especially those who do a lot of econometrics with “representative agent” models, they answer (if you insist quite a bit): “OK, I agree with you that it is nonsense to represent the whole economy by the (intertemporal) choice of one agent –- consumer and producer — or by a unique household that owns a unique firm; but if you don’t do that, you don’t do anything !”

Bernard Guerrien

Yes indeed — “you don’t do anything!”

Twenty years ago Phil Mirowski was invited to give a speech on themes from his book More Heat than Light at my economics department in Lund, Sweden. All the mainstream neoclassical professors were there. Their theories were totally mangled and no one — absolutely no one — had anything to say even remotely reminiscent of a defense. Being at a nonplus, one of them, in total desperation, finally asked “But what shall we do then?”

Yes indeed — what shall they do? The emperor turned out to be naked.

You’re done Tommy boy!

I really love this guy. He immediately goes for the essentials. He has no time for bullshit — and neither should we!

Formal mathematical modeling in economics — a dead-end

Using formal mathematical modeling, mainstream economists sure can guarantee that the conclusions hold given the assumptions. However, the validity we get in abstract model worlds does not warrantly transfer to real world economies. Validity may be good, but it isn’t enough. From a realist perspective both relevance and soundness are sine qua non.

In their search for validity, rigour and precision, mainstream macro modellers of various ilks construct microfounded DSGE models that standardly assume rational expectations, Walrasian market clearing, unique equilibria, time invariance, linear separability and homogeneity of both inputs/outputs and technology, infinitely lived intertemporally optimizing representative household/ consumer/producer agents with homothetic and identical preferences, etc., etc. At the same time the models standardly ignore complexity, diversity, uncertainty, coordination problems, non-market clearing prices, real aggregation problems, emergence, expectations formation, etc., etc.

Behavioural and experimental economics — not to speak of psychology — show beyond any doubts that “deep parameters” — peoples’ preferences, choices and forecasts — are regularly influenced by those of other participants in the economy. And how about the homogeneity assumption? And if all actors are the same – why and with whom do they transact? And why does economics have to be exclusively teleological (concerned with intentional states of individuals)? Where are the arguments for that ontological reductionism? And what about collective intentionality and constitutive background rules?

These are all justified questions – so, in what way can one maintain that these models give workable microfoundations for macroeconomics? Science philosopher Nancy Cartwright gives a good hint at how to answer that question:

Our assessment of the probability of effectiveness is only as secure as the weakest link in our reasoning to arrive at that probability. We may have to ignore some issues to make heroic assumptions about them. But that should dramatically weaken our degree of confidence in our final assessment. Rigor isn’t contagious from link to link. If you want a relatively secure conclusion coming out, you’d better be careful that each premise is secure going on.

On a deep level one could argue that the one-eyed focus on validity makes mainstream economics irrelevant, since its insistence on deductive-axiomatic foundations doesn’t earnestly consider the fact that its formal logical reasoning, inferences and arguments show an amazingly weak relationship to their everyday real world equivalents. Although the formal logic focus may deepen our insights into the notion of validity, the rigour and precision has a devastatingly important trade-off: the higher the level of rigour and precision, the smaller is the range of real world application. So the more mainstream economists insist on formal logic validity, the less they have to say about the real world.

Truth and economics (II)

Reading some of the comments on my earlier post on the status of truth in ‘modern’ economics, yours truly came to think of Robert Solow’s assessment of ludicrously ‘post-real’ model assumptions …

Suppose someone sits down where you are sitting right now and announces to me that he is Napoleon Bonaparte. The last thing I want to do with him is to get involved in a technical discussion of cavalry tactics at the battle of Austerlitz. If I do that, I’m getting tacitly drawn into the game that he is Napoleon. Now, Bob Lucas and Tom Sargent like nothing better than to get drawn into technical discussions, because then you have tacitly gone along with their fundamental assumptions; your attention is attracted away from the basic weakness of the whole story. Since I find that fundamental framework ludicrous, I respond by treating it as ludicrous – that is, by laughing at it – so as not to fall into the trap of taking it seriously and passing on to matters of technique.

Robert Solow

So much for the ’empirical’ revolution in economics

Sometimes a picture is worth a thousand words …

Source: Merijn Knibbe