The author defines development, or growth, as the ethically desirable direction of change. Is there a principle which can express what all developmental changes have in common, and what makes them desirable? The orthogenetic principle defines development as change towards increasing integration with complementary differentiation of people with respect to their environment. Heinz Werner and Bernard Kaplan first articulated this idea. It characterizes the portrayal of development by Jean Piaget, Lawrence Kohlberg, and John Dewey. None of these authors, however, justify orthogenesis as an ethical definition of development across a global range of experience. The author attempts this here, giving educators a tool for criticizing or justifying education having development as its aim. The author analyzes integration and differentiation into three aspects: co-ordination of distinguished elements in the environment; autonomous choice from a de-centered or objective perspective; immunity from environmental vicissitudes alongside an opening of and openness to the environment. Advancing these qualities is justified as ethically desirable in two ways. It overcomes the problem of egocentrism and habit-attachment which gives meaning to the notion of development across human experience. It also meets formal ethical criteria of universalizability, universality, and prescriptivity. Educators can use the orthogenetic principle to examine assumptions about development within psychological theories to see how these might themselves influence development. This enables educators to make eclectic use of psychologies within an ethical framework. The principle is also used to generate guidelines for thorough and objective inquiry into what is most growthful for a particular person at a particular time. The author argues that the principle cannot prescribe any educational course in advance of such inquiry into unique situations
