/Does it — really — take a model to beat a model? No!

Does it — really — take a model to beat a model? No!

from Lars Syll

Many economists respond to criticism by saying that ‘all models are wrong’ … But the observation that ‘all models are wrong’ requires qualification by the second part of George Box’s famous aphorism — ‘but some are useful’ … The relevant  criticism of models in macroeconomics and finance is not that they are ‘wrong’ but that they have not proved useful in macroeconomics and have proved misleading in finance.

kaykingWhen we provide such a critique, we often hear another mantra to which many economists subscribe: ‘It takes a model to beat a model.’ On the contrary, we believe that it takes facts and observations to beat a model … If a model fails to answer the problem to which it is addressed, it should be put back in the toolbox … It is not necessary to have an alternative tool available to know that the plumber who arrives armed only with a screwdriver is not the tradesman we need.

A similar critique yours truly sometimes encounters is that as long as I cannot come up with some own alternative model to the failing mainstream models, I shouldn’t expect people to pay attention.

This is, however, not only wrong for the reasons given by Kay and King, but is also to utterly misunderstand the role of philosophy and methodology of economics!

As John Locke wrote in An Essay Concerning Human Understanding:

19557-004-21162361The Commonwealth of Learning is not at this time without Master-Builders, whose mighty Designs, in advancing the Sciences, will leave lasting Monuments to the Admiration of Posterity; But every one must not hope to be a Boyle, or a Sydenham; and in an Age that produces such Masters, as the Great-Huygenius, and the incomparable Mr. Newton, with some other of that Strain; ’tis Ambition enough to be employed as an Under-Labourer in clearing Ground a little, and removing some of the Rubbish, that lies in the way to Knowledge.

That’s what philosophy and methodology can contribute to economics — clearing obstacles to science by clarifying limits and consequences of choosing specific modelling strategies, assumptions, and ontologies.

unnameadIt takes a model to beat a model has to be one of the stupider things, in a pretty crowded field, to come out of economics. … I don’t get it. If a model is demonstrably wrong, that should surely be sufficient for rejection. I’m thinking of bridge engineers: ‘look I know they keep falling down but I’m gonna keep building them like this until you come up with a better way, OK?’

Jo Michell