Lawrence Kohlberg, a Harvard professor, developed a six-stage theory of moral development influenced by Jean Piaget, proposing that ethical reasoning evolves through three primary levels: pre-conventional, conventional, and post-conventional, each consisting of two stages. The model suggests a fixed order of progression through these stages, highlighting how moral reasoning matures from a focus on self-interest to universal ethical principles. Kohlberg's stages range from obedience to punishment in young children to the development of individual moral guidelines that may contradict societal laws.