Models, which originate in metaphor, exist on several levels ranging from all inclusive metaphysical models to narrowly circumscribed models of specific features of theories. Models at the more general levels form the determining logical context for models at lower levels. This categorical determinism stretches from metaphysical levels through scientific theories, to the manner in which we analyze, interpret, and make inferences from empirical evidence. Two radically different models which have had a pervasive effect upon the nature of psychology generally and developmental psychology specifically are the organismic and mechanistic world views.