How entries are verified.

How verification works

After an entry is drafted, an independent verifier extracts every factual claim from the text — classical-source citations, named individuals, dates, statute references, organisational facts, study counts, dosages, anatomical claims, and any specific assertion that could in principle be checked against a public record. Each claim is then verified against the public record using multi-source search.

Every claim is sorted into one of five categories:

• Verified — at least two authoritative sources confirm, independently of each other.
• Partially verified — one authoritative source confirms; the second is weak or absent, or sources are slightly inconsistent on detail.
• Unverifiable — the claim is not contradicted by the public record, but neither is it directly confirmed within the verification budget.
• Contested — authoritative sources directly disagree, or the claim is contradicted by at least one authoritative source.
• Closed-source — the claim relies on a tradition-internal source (a classical text, a lineage transmission) that is itself the authority and cannot be verified against an independent external corpus. Closed-source claims are honestly labelled and excluded from the trust-score denominator.

Claims that come back unverifiable or contested are corrected, replaced with what the public record actually supports, or pulled from the entry. The correction is documented in an immutable audit history. A re-audit confirms that the corrections landed, and the new trust score is published.

The trust score

The trust score displayed on each entry is the percentage of that entry's factual claims that have been independently verified by at least two authoritative sources. The formula is:

trust_score = verified / (verified + partially_verified + unverifiable + contested)

Closed-source claims are excluded from the denominator. They are reported separately so the reader can see how much of the entry rests on tradition-internal authority versus the external public record.

Provisional scores

Some entries display their trust score with a small (provisional) label after the percentage. A provisional score means: the entry's last full audit found items to fix, those fixes have been applied to the source content, and the score has been recalculated on the assumption that those fixes now verify cleanly — but the independent re-audit that would confirm them has not yet run.

A full re-audit costs significant time and compute; corrections are pushed live as they land, with the next re-audit batched on a slower cadence. The provisional label is the honest acknowledgement that the corrections are in public but their confirmation pass is still pending.

Why this is disclosed

The verification state of an entry is the most useful single signal a reader can have about whether to rely on a page. Most content on the web is published without independent verification; the writer is the only verifier, and the reader has no way to know which claims were checked and which were not. Publishing the verification state moves that question from invisible to visible.

This is a methodological commitment, not a claim of perfection. Trust scores below 100% are normal — closed-source items exist, the public record is incomplete on certain topics, and the verifier itself can miss things. The commitment is that the score is honest and is published regardless of whether it is high or low. When an entry cannot be brought to an acceptable trust score, it is pulled until it can be.

Audit history

Every audit run on every entry is preserved as an immutable record at _porter/audit-history/<type>/<slug>/<timestamp>/ in the site repository. Each record contains the original fact-check report, the count of claims in each category, the items flagged for correction, and the corrections subsequently applied. Earlier audits are never overwritten — the timeline grows forward.

The editorial line of the site lives in the methodology page. This page is about the fact-check machinery underneath.