It's depressing that, after 40 years, we still need a robust defense of the goals of the sexual revolution, but it seems as if we do. In the intervening years, we seem to have forgotten that it was not all that long ago when women, but not men, paid a tremendous price for having sex while not married. (See "Downton Abbey" for a quick refresher: A housemaid with grander ambitions has a one-night fling with a handsome officer, gets pregnant, is fired from her job and exiled to a shed, where food is occasionally delivered to her.) Even after absorbing sex goddess Erica Jong, sex therapist Ruth Westheimer and a decade of...