Has a fairer America also become an America with less social mobility? That is the uncomfortable question raised by John Parker's long American survey in The Economist last month. "A decline in social mobility would run counter to Americans' deepest beliefs about their country," Parker writes. "Unfortunately, that is what seems to be happening. Class is reappearing in a new form." This was the conclusion, as well, of a recent series of articles in The New York Times -- although, as the Times and Parker both note, polls show that Americans think their chances of moving up are better than...