"True breakthroughs in understanding...come not from following the rulebook, but from tracking down its contradictions – and then rewriting it. From Socrates (who only knew that he knew nothing) to Russell (who asked whether a barber who shaved everyone in his shop who didn't shave themselves would also have to shave himself), great minds have been drawn to paradox. The economist Maurice Allais, who died at 99 this week, asked real people to choose between different gambles, and in the process sent rational economic man into a logical tailspin from which he has never recovered."