"For reasons that I have already discussed one cannot know that the sun will rise tomorrow. Yet at the same time, most people in the world would be happy to bet a large sum of money on the proposition that it will rise tomorrow. So most of us are happy to base our behavior on the supposition that the sun will rise tomorrow. True, there are a handful of fruitcases who would argue that the sun is not going to rise tomorrow - for the End of The World is Nigh - but they are in a minority. One cannot say that these fruitcases are wrong - at least not until tomorrow, by which time it may be too late! - and certainly one cannot prove that they are wrong. Nor indeed can one use the fact that most of the people in the world think they are wrong as a basis for arguing that they are wrong.

This reminds me of a conversation that I had with an eminent economics at a distinguished English university a year or so ago after I had given a seminar there. We were discussing the goodies and the baddies in the faculty there - the goodies being the eminent economist's small band of neoclassical colleagues, and the baddies being the dreaded M*rx*sts. The baddies are a great force for reaction in the faculty, and the eminent economist was complaining how he found them a permanent millstone round his neck. I remarked something to the effect: 'Why doesn't the fact that you and your band are doing lots of good work and getting it published in good journals, while the M*rx*sts are doing nothing of any value at all and publishing at best in second-rate journals, not help in the political process of decision-making in your University? Surely everyone knows that they have to take you seriously and dismiss the claims of the lefties because it is you that brings in all the Brownie Points for Economics at this University?'

The eminent economist replied that the M*rx*sts did not accept that the fact that they published in 'second-rate' journals while the eminent economist's band published in Econometrica and the Review of Economic Studies was any kind of evidence that they were bad and the neoclassicists good. On the contrary, this was just evidence of a counter-revolutionary plot against the true scientific research that the M*rx*sts were doing. Meanwhile, the rest of the faculty, who were sitting round politely listening to this debate, being good middle-class intellectuals, declared the M*rx*sts the winners on the grounds that the eminent economist had not proved his point. Which was indeed true (even if morally disastrous).

So what is the moral of this little story? If you insist on logical proofs of propositions you end up with an economics department with a lower research ranking? Possibly. And if you insist on some logically defensible definition of rationality you waste lots of time in seminars rather than doing serious work...

Whether you like it or not, economists are better than most other people (statisticians and chancellors of the exchequer alike) at predicting (and perhaps, by implication, explaining) economic behaviour."

--- Rationality is as Rationality Does, John D. Hey