What got us into our financial pickle? Most academics are prisoners of the Efficient Market Hypothesis that assumes man acts rationally and efficiently in economic matters in ways that can be caught in elegant mathematical models. Ben Bernanke, chairman of the Federal Reserve, shares this view completely, and Alan Greenspan, his predecessor, when it suits him. In such a convenient world, there can be no bubbles and no crashes. A related belief is that sensible, disciplined control of money supply will drive away all ills, including the madness of crowds, and, therefore, a sensible central banker is all powerful.

Unfortunately, both concepts are complete illusions. First, we live in a behavioural jungle where markets can crash 23 per cent in a day without any defining event, price/earnings ratios in Japan can rise to 65 times and the value of land under the Emperor’s palace really can equal California’s. Second, central bankers do not always do the right thing, often because that would involve great career risk. Being slapped by a Senate subcommittee for saying “irrational exuberance” is bad enough. Taking away punch bowls and risking being seen as holding the pin when the bubble pops is even more dangerous stuff.