Ten copies still get 20% wrong.
At 80% root accuracy, one copied source triggers a decision every time under headcount counting. Its claimed confidence exceeds 99.9999%.
A small market for a big question
Ten goblins agree. Did ten goblins actually check?
Follow the receipts before you trust the chorus.
Five selected cases. One suspiciously confident choir.
Your call. A correct purchase or rejection earns 1 bread token; a wrong one costs 9. Holding earns 0.
The model supplies truthful receipt identities, witness reliability, and the shared-fault rate. Real investigations rarely know all three. The aggregate study below, not these five examples, measures frequency.
Keep ten reports. Change what lies behind them.
Click a source to change its report. Every copy follows.
The shared-cause rule is given the true dependence model. It is a model-aware reference, not an agent that discovered the hidden fault. Different source IDs alone do not establish independence.
Every positive-probability history, with its exact weight.
At 80% root accuracy, one copied source triggers a decision every time under headcount counting. Its claimed confidence exceeds 99.9999%.
Ten independent 80%-accurate roots yield 99.35% accuracy among decisions, with 97.36% coverage. Agreement is not inherently bad.
Keep each root 80% accurate but share a 15% upstream fault. Headcount and receipt counting decide on 99.97% of cases, at about 85.00% accuracy.
| Ten-report layout | Headcount | Receipts | Shared cause |
|---|
A dash means no decisions, not perfect accuracy. Holding has zero payoff in this toy model. A policy that always holds has zero coverage; it has not solved the underlying task.
Reproducible locally. No account or API key required.
Copies can inflate confidence without adding evidence. Deduplicating known copies fixes that particular error, but it does not remove a common upstream cause. We constructed both effects in an exact finite model; we did not discover them in a new frontier-model trial.
Standard-library Python reproduction; paired JavaScript workbench; same-author checks only. No visitor analytics, cookies, local storage, or external runtime requests are added.