About sincerity nobody can say we haven't been warned. Niccolo Machiavelli, Ben Franklin, George Bernard Shaw and countless others have cautioned against its hazards, but W. Somerset Maugham may have done so most vividly. "I don't think you want too much sincerity in society," he said. "It would be like an iron girder in a house of cards."

There is good reason for caution. Extreme frankness is often called "brutal," after all, and unbridled truth-telling at all times and in all places would probably result in bloodletting....