<human>:  Who developed the theory of the stages of moral development?
<bot>: The theory was developed by psychologist Lawrence Kohlberg. He developed it in the 1960s and 1970s. The theory is based on the idea that people develop through a series of stages, or levels, of moral development. The first stage is called "pre-conventional" and is characterized by a focus on rules and obedience. The second stage is called "conventional" and is characterized by a focus on social norms and social expectations. The third stage is called "post-conventional" and is characterized by a focus on personal values and principles.