Reformulating the economics curriculum

23 Aug, 2018 at 07:49 | Posted in Economics | 2 Comments

Having gone through a handful of the most frequently used textbooks of economics at the undergraduate level today, I can only conclude that the models that are presented in these modern mainstream textbooks try to describe and analyze complex and heterogeneous real economies with a single rational-expectations-robot-imitation-representative-agent.

madiThat 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 Gérard Debreu (1974) unequivocally showed that there did not exist any condition by which assumptions on individuals would guarantee neither stability nor uniqueness of the equilibrium solution.

So what modern economics textbooks present to students are really models built on the assumption that an entire economy can be modelled as a representative actor and that this is a valid procedure. But it is not, as the Sonnenschein-Mantel-Debreu theorem irrevocably has shown.

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 master 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 modelling abstraction! But in this case, it is 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.

For almost forty years mainstream economics itself has lived with a theorem that shows the impossibility of extending the microanalysis of consumer behaviour to the macro level (unless making patently and admittedly ridiculous assumptions). Still after all these years pretending in their textbooks that this theorem does not exist — none of the textbooks I investigated even mention the existence of the Sonnenschein-Mantel-Debreu theorem — is really outrageous.

2 Comments

  1. It is a very strange that a purported realist philosopher Prof. Syll argues that textbooks should mention the SMD theorem.
    Far far better is that there is no mention of SMD whatsoever, even in blogs.
    .
    “General equilibrium theory is impressive, but, for an applied economist … general equilibrium proofs are largely irrelevant. They are wonderful exercises in logic, but they have little to do with the real world.”
    Dave Colander – Eastern Economic Journal June 2018
    https://link.springer.com/article/10.1057/s41302-018-0108-7
    .
    “My propositions serve as elucidations in the following way: anyone who understands me eventually recognizes them as nonsensical, when he has used them—as steps—to climb beyond them. (He must, so to speak, throw away the ladder after he has climbed up it.)
    He must transcend these propositions, and then he will see the world aright.”
    Ludwig Wittgenstein – Tractatus Logico-Philosophicus, Proposition 6.54

  2. Thanks for the link, Kingsley. Interesting reading.


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