On the non-existence of economic laws21 February, 2016 at 09:57 | Posted in Economics | Leave a comment
In methodischer Hinsicht verdankt das ökonomische Erkenntnisprogramm ohne Zweifel dem Einfluss der klassischen Physik eine wichtige Komponente, nämlich den Gedanken, dass die sozialen Phänomene ebenso von Gesetzmässigkeiten beherrscht sind wie die Naturerscheinungen und dass es daher angezeigt ist, solche Gesetzmässigkeiten zu suchen und theoretisch in ähnlicher weise zu kodifizieren, wie Newton das für die Gesetze der Mechanik in seinem System geleistet hatte.
The crux of these laws — and regularities — that allegedly do exist in economics, is that they only hold ceteris paribus. That fundamentally means — as repeatedly and strongly argued by e. g. Nancy Cartwright — that these laws/regularites only hold when the right conditions are at hand for giving rise to them. Unfortunately, from an empirical point of view, those conditions are only at hand in artificially closed nomological models purposely designed to give rise to the kind of regular associations that economists want to explain. But, really, since these laws/regularities do not exist outside these ‘socio-economic machines,’ what’s the point in constructing these non-existent laws/regularities? When the almost endless list of narrow and specific assumptions necessary to allow the ‘rigorous’ deductions are known to be at odds with reality, what good do these models do?
Take The Law of Demand.
Although it may (perhaps) be said that neoclassical economics had succeeded in establishing The Law – when the price of a commodity falls, the demand for it will increase — for single individuals, it soon turned out, in the Sonnenschein-Mantel-Debreu theorem, that it wasn’t possible to extend The Law to apply on the market level, unless one made ridiculously unrealistic assumptions such as individuals all having homothetic preferences – which actually implies that all individuals have identical preferences.
This could only be conceivable if there was in essence only one actor – the (in)famous representative actor. So, yes, it was possible to generalize The Law of Demand – as long as we assumed that on the aggregate level there was only one commodity and one actor. What generalization! Does this sound reasonable? Of course not. This is pure nonsense!
How has neoclassical economics reacted to this devastating findig? Basically by looking the other way, ignoring it and hoping that no one sees that the emperor is naked.
Modern mainstream neoclassical textbooks try to describe and analyze complex and heterogeneous real economies with a single rational-expectations-robot-imitation-representative-agent. That is, with something that has absolutely nothing to do with reality. And – worse still – something that is not even amenable to the kind of general equilibrium analysis that they are thought to give a foundation for, since Hugo Sonnenschein (1972) , Rolf Mantel (1976) and Gerard Debreu (1974) unequivocally showed that there did not exist any condition by which assumptions on individuals would guarantee neither stability nor uniqueness of the equlibrium solution.
Of course one could say that it is too difficult on undergraduate levels to show why the procedure is right and to defer it to masters and doctoral courses. It could justifiably be reasoned that way – if what you teach your students is true, if The Law of Demand is generalizable to the market level and the representative actor is a valid modeling abstraction! But in this case it’s demonstrably known to be false, and therefore this is nothing but a case of scandalous intellectual dishonesty. It’s like telling your students that 2 + 2 = 5 and hope that they will never run into Peano’s axioms of arithmetics.
As Hans Albert has it:
The neoclassical style of thought – with its emphasis on thought experiments, reflection on the basis of illustrative examples and logically possible extreme cases, its use of model construction as the basis of plausible assumptions, as well as its tendency to decrease the level of abstraction, and similar procedures – appears to have had such a strong influence on economic methodology that even theoreticians who strongly value experience can only free themselves from this methodology with difficulty …
Clearly, it is possible to interpret the ‘presuppositions’ of a theoretical system … not as hypotheses, but simply as limitations to the area of application of the system in question. Since a relationship to reality is usually ensured by the language used in economic statements, in this case the impression is generated that a content-laden statement about reality is being made, although the system is fully immunized and thus without content. In my view that is often a source of self-deception in pure economic thought …