Beyond Definition: An Operational Criterion for Life, in Response to Cleland's Challenge

The definition of "life" remains one of the most contested questions in contemporary biology. Carol Cleland has argued, across an influential series of works, that attempting to define life is an epistemic error: in the absence of a general theory of life, every definition is premature and destined to fail against counterexamples. NASA's own operational definition — "a self-sustaining chemical system capable of Darwinian evolution" — does not withstand well-known objections (the mule problem, the Joyce/Lincoln case, the exclusion of viruses). The present paper accepts Cleland's invitation to abandon rigid definitions, but — in the spirit already opened by Bich and Green (2018) — proposes that operational criteria need not be abandoned, but rather reformulated with greater rigour. To this end, the present work introduces the O.O.A. criterion (Oxidation, Homeostasis, Avery-positivity), a tentative criterion with three conditions, grounded in thermodynamics and in the principle of causal transmission of hereditary information, accompanied by an independent quantitative criterion — the Malthusian criterion — based on the constant e as the signature of autonomous biological growth. The criterion is tested on limit cases (flame, virus, mule, android, prion, synthetic cell, hypothetical silicon-based life) and applied to the philosophical problem of the O.O.A.-positive artificial entity, where the criterion itself, when applied consistently, generates an identity paradox that reaches the heart of the Western logical framework concerning being. The paper defends, on grounds of epistemic parsimony, the position that this paradox requires the postulate of intrinsic embodied properties in living matter — a move analogous to that defended by the author in a parallel work on final causation in the moral subject.