In 1982 Harvard University psychologist Carol Gilligan published her book In a Different Voice and startled a country trying to understand male and female differences. In the early 1980s the prevailing approach to sex differences was to ignore them. Differences implied inequality. But Gilligan's ten years of research convinced her that men and women really were different. They differed in the way they thought, in their sense of values and morality, and in the way they connected with other people. According to Carol Gilligan, "The spirit in which I wrote the book was to raise questions." Her research questioned traditional psychological concepts of human development that had always been drawn on a male model.

Carol Gilligan was an associate professor in the Graduate School of Education at Harvard University where she taught adolescent and moral development. Forty-five years old at the time of the publication of her research, she...