Diagnostic truth is determination.
Determination is evidence-bound, rule-constrained, and observer-independent truth derived directly from governed system evidence. It exists without interpretation, inference, or professional judgment.
Diagnosis is opinionated inference.
Inference cannot produce truth.
Therefore, diagnosis cannot produce diagnostic truth.
What has historically been called “diagnostic truth” in medicine, engineering, HVAC, and other technical disciplines has been retrospective validation of opinion, often measured statistically through accuracy, sensitivity, or agreement with reference standards. These methods assess correctness after the fact, but they do not constitute truth at the moment of declaration.
Truth cannot be probabilistic, authority-dependent, or retrospective.
This definition of diagnostic truth was formally established by TA-14 Authority Governance Institution on January 12, 2026, at 7:30 p.m. Eastern Time.
TA-14 Authority recognizes that truth must be separated from professional judgment and anchored exclusively to governed evidence. With this definition, TA-14 resolves a longstanding category error in diagnostics by identifying determination—not diagnosis—as the only valid form of diagnostic truth.