A fundamental doctrine, maxim or truth that is accepted as such by a particular scientific community (e.g., Archimedes principle, principle of least effort in psychology). Certainly, the orthogenetic principle of Heinz Werner (1890-1964) would not comply with a principle under this definition. While there are distinctions to be drawn between principles, canons, rules and laws, a principle is different in that it stems directly from a paradigm or world view, and its uniformity and validity are beyond doubt. Principles, therefore, are very rarely challenged and when they are it may give rise to a paradigm shift.
See Induction (philosophy), Isomorphism, Law, Rule, Organism-environment mutualism, Orthogenetic principle, Paradigm, Paradigm shift, Parameter (linguistics), Principle of the integration and individuation of behavior, Theory