Several epistemic formulations have been advanced to explain cognitive development. Many writers have divided the field of psychology into three basic underlying models: the mechanistic, organismic, and dialectic models. An examination of epistemic positions reveals five broadly defined positions on how behavior develops within a given organism. In position I, one can adhere to the notion that behavior and/or knowledge is innately inset. Within this position are the organismic viewpoints of Leibnitz, Gesell, and Descartes. In position II, the organizational elements necessary to a particular behavioral development are seen as either innately inset or as developing along epigenetic guidelines, while particular content displayed is seen as resulting from interaction with the external environment. Within position II are the organismic views of Kant and Piaget. Position III arises within the dialectical paradigm of Hegel and holds that factors intrinsic and extrinsic to the organism are necessary both to the organization and content of knowledge. Position IV, in the dialectical paradigm of Marx, holds that an active organism both generates changes in the structure and organization of the external environment and derives organization and content of its intellect from external sources. In position V, both form and content of behavior are derived passively from external sources, with some account being taken of the material realities as causal in the organism. This mechanistic view is found in more radical forms of behaviorism. (NB)