1. Introduction
Health systems treat time as metadata.
Events are recorded, revised, normalized, summarized, and reissued as if temporal order were secondary to present interpretation. Corrections replace prior state. Knowledge arrival is conflated with event occurrence. History is rewritten to reflect current understanding.
These practices erase causality.
When systems permit rewrite, they cannot distinguish correction from fabrication. Longitudinal reasoning collapses. Automation amplifies distortion. Audit becomes interpretive rather than structural.
This paper formalizes time and irreversibility as non-negotiable properties of canonical health state.
2. Event Time and Assertion Time
Health-relevant facts occur in time. Knowledge about those facts may arrive later.
HealthMemory distinguishes:
- Event time, when a condition, observation, or occurrence took place
- Assertion time, when that information was recorded as canonical state
These times may differ. Both are preserved.
Systems that collapse these concepts lose the ability to reason longitudinally. Late-arriving knowledge becomes indistinguishable from revision. Temporal inference becomes unstable.
3. Append-Only State
Canonical state is append-only.
New assertions may reference prior assertions. They may contradict them. They may contextualize them. They may invalidate their relevance. They may not remove them.
Append-only state preserves:
- Temporal ordering
- Historical uncertainty
- Evolution of understanding
- The difference between what occurred and what was later believed
Rewrite replaces history with interpretation. Append-only preserves both.
4. Irreversibility
Irreversibility is a structural requirement.
Once an assertion is recorded, it cannot be erased, modified, or replaced. Any attempt to remove state collapses causal traceability.
Irreversibility does not imply correctness. It implies accountability.
A system that permits deletion or mutation of canonical state cannot preserve longitudinal truth under scrutiny.
5. Contradiction Without Erasure
Contradiction is not an error condition.
Health-relevant state is incomplete, ambiguous, or contested. Different observers may assert conflicting information. Understanding evolves over time.
HealthMemory preserves contradiction by allowing multiple assertions to coexist.
Resolution is deferred to derived systems. Canonical state records what was asserted, not what was ultimately believed.
Systems that resolve contradiction by overwrite erase evidence of disagreement and force premature consensus.
6. Temporal Gaps
Absence of information is itself information.
HealthMemory preserves gaps in time without imputation. Silence is not inferred. Missing data is not normalized.
Temporal continuity is not assumed. Longitudinal integrity requires acknowledging where knowledge does not exist.
Derived systems may infer or interpolate. Canonical state may not.
7. Revision as Assertion
Correction is modeled as addition, not replacement.
When new understanding emerges, it is asserted as new canonical state. The prior assertion remains, contextualized by subsequent assertions.
This preserves:
- The original claim
- The conditions under which it was made
- The evolution of understanding over time
Revision that erases prior state destroys the ability to reason about error, bias, or change.
8. Longitudinal Integrity
Longitudinal integrity is the ability to reconstruct health-relevant state across time without loss of causality.
It requires:
- Explicit event and assertion times
- Append-only state
- Irreversibility
- Preservation of contradiction
- Preservation of absence
Without these properties, longitudinal analysis degenerates into retrospective narrative.
9. Invariants
The following invariants hold:
- Event time and assertion time are distinct
- Canonical state is append-only
- Assertions are irreversible
- Revision is modeled as addition
- Contradiction is preserved
- Absence is not inferred
- Temporal gaps are preserved without imputation
Violating any invariant collapses longitudinal integrity.
10. Discussion
Time is not a convenience. It is a structural constraint.
HealthMemory treats time as a first-class property and irreversibility as a defense against distortion. By preserving causality, contradiction, and absence, canonical state remains stable under correction, automation, and scale.
Longitudinal integrity is not achieved through better interpretation. It is achieved through refusal to rewrite.