Diagnostics and Empirical Tractability

This article develops the methodological and empirical dimensions of APS diagnosis. APS diagnosis evaluates viability-oriented organisation through perturbation, regulation, evaluation, semiosis, and persistence-maintaining activity rather than through trait lists or static classification. Diagnosis in APS is explanatory, organisational, perturbational, and graded rather than merely classificatory.

This article clarifies what counts as evidence for life in the APS framework. It distinguishes definition, diagnosis, and evidence, and shows that biological evidence is not behavioural but organisational—indicating viability-oriented, constraint-closed organisation across scale.

APS distinguishes between defining life and diagnosing its presence. The framework defines life ontologically as viability-oriented, constraint-closed organisation, but argues that recognising such organisation in practice requires diagnostic evaluation rather than trait-based classification. This article explains why APS approaches life as a diagnostic target revealed through perturbation, repair, persistence, and organisational failure.

This article explains how the Agency–Process–Scale (APS) framework approaches the problem of life detection. APS argues that life is not identified through isolated traits, molecules, or signatures alone, but through evidence of viability-oriented organised persistence. Biosignatures are interpreted as indicators of underlying organisation rather than as definitions of life themselves. By distinguishing direct diagnosis from indirect inference, APS provides a framework for evaluating biological, artificial, synthetic, and extraterrestrial systems through evidence of persistence-maintaining organisation.

APS treats malfunction, breakdown, and death as revealing relations to organised persistence within viability-oriented living systems. Malfunction is impaired functioning within an organisation that continues to persist; breakdown is erosion of the capacity through which that organisation maintains and re-establishes the conditions of its persistence; and death is collapse of the viability-oriented organisation through which the organism exists as that organism. Failure therefore provides a diagnostic window into biological organisation without replacing the mechanistic and empirical explanations required for particular cases.

APS reframes biological diagnosis as the evaluation of viability-oriented organisation rather than the identification of traits, mechanisms, or components. This article defines diagnosis within the APS framework and clarifies how it differs from traditional biological and medical approaches.

Cognitive Integration (CI) is a core diagnostic dimension in APS, expressing the degree to which a system coordinates its activity across processes, time, and scale in sustaining its own viability. CI distinguishes simple reactive adjustment from integrated, system-wide regulation, but does not by itself constitute cognition, which additionally requires viability-oriented evaluation with temporal depth.

This article develops an APS account of diagnosis as the analysis of continuity, perturbation, compensation, resilience, and reorganisation within viability-oriented systems. Diagnosis is not treated merely as the identification of isolated defects or symptoms, but as the investigation of how temporally organised persistence succeeds, destabilises, compensates, recovers, or fails across interacting biological processes and scales. APS therefore reconstructs diagnosis around continuity analysis within dynamically organised living systems.

The Normativity Gradient (NG) is a core diagnostic dimension in APS, expressing the degree to which a system’s activity is oriented toward sustaining its own viability. Rather than invoking intention or evaluation in a mental sense, NG captures the endogenous organisation through which systems differentiate between conditions that support or degrade persistence.

The Viability Gradient (VG) is a central diagnostic dimension in APS, capturing the degree to which a system sustains its own persistence under changing conditions. Rather than treating life as a binary property, VG provides a continuous measure of how effectively viability-oriented organisation is maintained across time and scale.

This article establishes the diagnostic dimension of the APS framework. It shows how claims about viability-oriented, constraint-closed organisation can be empirically evaluated through perturbation, organisational response, and viability-relative outcomes, thereby making APS an operational and testable framework for biological explanation.

If agency is the defining activity of life, it must be empirically tractable. In the Agency–Process–Scale (APS) framework, agency can be investigated through two complementary forms of evidence: organisational signatures and perturbation responses. Organisational signatures reveal the stable patterns produced by viability-oriented activity, while perturbation responses reveal the regulatory dynamics through which viability is maintained. Together they provide a unified framework for diagnosing living systems, evaluating marginal cases, and extending life detection beyond familiar biological contexts.

This article applies the APS diagnostic framework to a plant system, demonstrating how viability-oriented organisation can be evaluated in practice. Using perturbation and the three diagnostic dimensions—Viability Gradient (VG), Normativity Gradient (NG), and Cognitive Integration (CI)—it shows how plant activity reveals biological agency without requiring neural or representational explanations.

APS distinguishes between malfunction within a system and the collapse of the organisation that sustains its viability. This article applies the APS diagnostic framework to cases of breakdown, showing how failure is identified when viability-oriented organisation can no longer be maintained across time and scale.