This is a theory proposed by psychologist Lawrence Kohlberg that suggests our moral reasoning, or how we make decisions about right and wrong, develops in stages as we grow.
Kohlberg's theory of moral development suggests that moral reasoning progresses through a series of stages, from pre-conventional to conventional and finally to post-conventional morality.
Lawrence Kohlberg's key research included longitudinal studies where he presented moral dilemmas, like the "Heinz dilemma," to assess moral reasoning across different ages, supporting his stage theory.