Claim · base rate .50 · resolves on day 90

The night ferry is running again by June.

One claim's probability, drawn as the days pass, with its uncertainty band. Five sources of different reliability report yes or no. Each report moves the belief by a bounded step, a story another outlet runs again is counted once, the belief drifts back towards even odds as it forgets, and when the claim resolves the sources are graded. Choose a source to have it report.

Fig. 11 — One claim, five sources. Saying it twice doesn’t make it truer.

Episteme is a belief engine I built at Tacita, and it treats sources like sensors in a state estimator. Each report moves the belief by a step scaled to how far its source is trusted, and no single report can move the odds more than about fourfold. A story that five outlets run on the same day counts once. When a claim resolves, the sources that reported on it get graded, and after five graded reports a source's reliability starts to follow its record.

The update rules are Episteme's, and the claim and sources are invented. Every report carries the same likelihood ratio, and the belief forgets on a single 30-day half-life. The band is the 10th to 90th percentile of the Beta distribution Episteme stores the belief as, and its darker core the 25th to 75th.

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