Robert B. Blake and Deborah Anne Carroll have created a scientific model for ethical decision-making for business people based on Kohlberg's three levels and six stages of human development. The model is flawed on two accounts: Kohlberg's research excluded women; and the model relies too much on psychology. The authors preclude philosophical grounds for ethical decision making and rely on mature people's predilection to act on universal, altruistic principles. Psychological grounds of conduct do not readily translate into grounds that lead to proper and consistent moral conduct. Moral philosophy is superior to psychology in that it: delineates the grounds for ethical decision making; justifies when a person should and should not act; and provides principle why one act is preferable to another.