From deceptive advertising to misguided public policy to sheer boneheadedness, Americans have no shortage of forces pushing them to make unwise choices. How else to explain Ding-Dongs? Or ruining a perfectly good planet? Legal scholar and avowed environmentalist Cass Sunstein, however, holds out hope that we, both individually and collectively, are not condemned to irrationality. In Nudge: Improving Decisions About Health, Wealth, and Happiness (released in paperback last month), Sunstein and co-author Richard Thaler explain how enlightened "choice architecture" can close the gap between hedonism and wisdom though "libertarian paternalism": a kind of minimalist interventionism designed to remedy some of …