At first, Steven Levitt is not sure where we should go for lunch. We’re meeting in his home city of Chicago, a place I have never visited, so I haven’t a clue what to suggest. He says he will get some advice and eventually comes up with the South Water Kitchen, a downtown bar and restaurant a few miles from his office at the University of Chicago.

And so here, over a can of Coke and an $11 hamburger, I meet the surprisingly uncontroversial-looking Steven D. Levitt. Surprising because, despite his average hair, his average height and his very average shirt and Chinos, the 37-year-old Levitt is one of the most notorious economists of our age.