The Triadic Principle of Biology: A Testable Hypothesis About Functional Closure in Living Systems

Systems biology maps extensive networks but lacks a general principle identifying the minimum functional architecture of living organization. The Triadic Principle of Biology (TPB) proposes that stable, self-regulating biological systems require coordinated closure among three functionally distinguishable domains: Information, Energy/Material Transformation, and Interface/Boundary. These are categories of biological work rather than anatomical structures. This article states the claim, gives explicit rules for assigning a process to a domain and for fixing the system boundary, defines autonomy independently of the framework, and evaluates candidate manifestations in genetic coding, translation, cellular organization, epigenetics, development, physiology, evolution and disease against prospective admissibility criteria. The codon inequality provides one exact result, but it concerns code word length rather than functional domains and is not evidence for the TPB. The framework contributes a standardized functional vocabulary, criteria distinguishing genuine triads from arbitrary groupings, a taxonomy of failure modes, an operationalized closure index with explicit scoring functions and a worked example, and falsifiable predictions, including specified comparisons against rival decompositions such as sensing–regulation–action, supply–demand–control and Wicken’s exploitation–homeostasis dyad. Gánti’s chemoton is identified as the closest formal antecedent. Because these predictions remain untested, the article specifies the experiments and outcomes that would support, weaken or reject the principle.