Yet whenever Dubner and Levitt pop up to explain how catchy and wondrous their theories are, it's with a touch of nerd smugness, since most of what they say sounds not so much brain-tickling as obvious. The final segment, in which delinquent kids are bribed to study to see if it will raise their grades, is morally myopic: Even if the bribes did work, what would that teach a kid? As a movie, Freakonomics is like Jujubes for the brain — it starts to get cloying halfway through the box.
