While serving as professor of education and social psychology at Harvard University, Kohlberg refined his theory of moral development. He forced a rethinking of traditional ideas on moral development by asserting that one’s maturity in moral decisions develops as one thinks about moral issues and decisions. With cognitive growth, moral reasoning appears, and moral reasoning allows children to gain control over their moral decision-making process. From approximately four years of age through adulthood, a person experiences six stages of development that are divided into three levels. Because it is a cognitive developmental process, moral reasoning is taught using scenarios of moral dilemmas, causing students to justify the morality of their choices. Upon reaching cognitive maturity, a person will use reason to fashion an ethic of justice that is consistent with universal principles of justice and use it to satisfy the moral dilemma. For Kohlberg, moral judgment is the key ingredient in morality, taking precedence over other noncognitive factors. Some critics have challenged the universal application of the theory by claiming that the path of moral development is different for women.