The principle is Morgan’s Canon, which says animal behavior should not be explained by higher mental processes when simpler processes suffice.
The canon is associated with British psychologist C. Lloyd Morgan and is a rule for interpreting animal behavior cautiously. It warns researchers not to assume humanlike reasoning, intention, or consciousness when learning, instinct, or simpler mechanisms provide an adequate explanation.
Morgan developed the principle in the context of late-19th-century comparative psychology, partly in reaction to anecdotal and anthropomorphic interpretations. His observations of his terrier Tony opening a gate suggested that behavior resembling insight could emerge through gradual trial and error.
Morgan’s Canon is not identical to Occam’s Razor, although both favor parsimonious explanations. Modern animal-cognition researchers also caution that the canon can be oversimplified: a simple explanation is not automatically correct, and evidence may support sophisticated cognition. Pavlov’s Law and Tinbergen’s Rule are not the canonical names for this principle.