Fail-closed reasoning: the operational definition.
In safety-critical systems, "fail-closed" means the system defaults to a safe state when it encounters conditions it cannot handle. Applied to decision infrastructure, fail-closed reasoning means: when the evidence base is insufficient to support an assertion, the system withholds the assertion rather than generating a plausible-sounding substitute.
This is the architectural response to the $67.4 billion annual cost of AI hallucination in enterprise environments. The platform does not eliminate uncertainty - it makes uncertainty visible, auditable, and actionable. A decision-maker who knows where the evidence gaps are can act on that knowledge. A decision-maker who receives confident-sounding outputs from an ungoverned system cannot.