noun A doctrine, in several fields, that the function of something should be reflected in its design and the materials used in its construction.
noun The definition of mental states in terms of their causes and effects.
noun The idea that social and cultural cohesion are a function of the interdependence and interactions of the institutions of a society.
noun The theory that the Holocaust was the result of a gradual escalation of decisions and procedures at the operational level (approved but not necessarily preconceived by Hitler).
noun A general school of thought that considers psychological phenomena in terms of their role in adaptation to the person's environment.