Consistency is the first siren of beauty. The claim is made by John Cochrane, professor of economics at the University of Chicago, in a blistering response to Paul Krugman’s critique of modern economics. A little over the top perhaps. It is not consistency that takes our breath away when we see the Taj Mahal or the Mona Lisa.
But Prof Cochrane correctly identifies consistency as the most prized virtue in economic reasoning. If I am faced with the same menu of options, I will always make the same choice. This is the premise on which rational choice models are based. Such models not only dominate economics but have been widely used across the social sciences.
Consistency is not what is ordinarily meant by rationality. If I commune daily with the fairies at the bottom of the garden, I am consistent but hardly rational. Still, even if consistency is not sufficient for rationality, surely it is necessary?