Gilligan's work, which focuses on sex differences in moral reasoning, the perception of violence, the resolution of sexual dilemmas and abortion decisions, poses a major challenge to Kohlberg's theory by introducing a feminist perspective of moral development. Kohlberg had shown that the average female attained a moral judgment rating of stage three (good boy-nice girl), while adolescent males score at level four (law and order) and are more likely to move on to postconventional levels. Gilligan suggests that these findings reveal a gender bias, not that females are less mature than boys. Men and women follow different voices. Men tend to organize social relationships in a hierarchical order and subscribe to a morality of rights. Females value interpersonal connectedness, care, sensitivity, and responsibility to people. Kohlberg's scoring criteria give the interpersonal care orientations of females lower ratings than the principled justice orientation. Hence, Gilligan identifies different developmental stages for females. However, she does not claim that one system is better; both are equally valid. Only by integrating these complementary male (justice) and female (care) orientations will we be able to realize our full human potential in moral development.