Making trust computable
Evidence is not free. Every cryptographic receipt, every witness signature, every formal proof has a cost. Evidence Economics defines the grades, retention policies, and incentive structures that make verifiable autonomy economically sustainable.
Four levels of assurance
| Grade | Name | Description | Retention | Cost |
|---|---|---|---|---|
| E0 | Assertion | Principal claims action occurred. No independent verification. | 30 days | Free |
| E1 | Receipted | Cryptographic receipt with input/output hashes and PrevHash chain. Offline-verifiable. | 1 year | Included |
| E2 | Witnessed | Multi-party attestation. At least one independent witness co-signs the DecisionRecord. | 3 years | Per-witness |
| E3 | Formally Verified | TLA+/Lean proof of correctness. Mathematical guarantee that invariants hold. | Permanent | Compute-bound |
Evidence has a shelf life
Hot evidence
Recent execution receipts, active Decision Records, and uncommitted CommitTokens. Stored in-memory or fast storage. Available for real-time verification and replay. Retention: session duration + configurable buffer.
Cold evidence
Historical EvidencePacks, archived Decision Records, and completed ProofGraph segments. Stored in content-addressable storage (CAS). Available for audit, compliance, and regulatory inquiry. Retention: per evidence grade.
Why produce evidence?
Liability reduction
Signed Decision Records establish a deterministic audit trail. The principal can prove they operated within authorized boundaries.
Insurance pricing
Higher evidence grades → lower premiums. E2 (witnessed) evidence reduces risk assessment. E3 (formally verified) approaches actuarial zero.
Regulatory compliance
Evidence packs satisfy SOC 2, ISO 27001, and HIPAA audit requirements. Automated export eliminates manual evidence collection.