Since the death of John F. Kennedy, the early hagiography has given way to a sharply critical, revisionist portrait that depicts a mediocre president whose domestic program was a dismal failure. Kennedy was a man of words, not of deeds, one critic wrote, and his achievements "were less significant than James K. Polk." But in Promises Kept, eminent historian Irving Bernstein argues that "the revisionists are dead wrong." By 1963, Kennedy had become...