an account of an event, behavior, or thought that is couched in terms of an established set of scientific principles, facts, and assumptions. Typical forms of explanation may be reductionistic, analyzing a phenomenon into components and describing how they combine to produce the phenomenon; ontogenic, relating the phenomenon to a universal set of developmental stages; empiricistic, describing a phenomenon in terms of the conditions that have been observed to produce it; or metaphoric or categorical, identifying a phenomenon as similar in some important respects to other phenomena already understood. Such an explanation stated systematically is generally known as a theory.