reasoning
Of the 15 HSM shops sampled 10+ times, 12 had no positive sars-cov-2 samples, 3 had one, and shop 6:29 had 5; more careful analysis places 6:29 at the geographic center of the positivity ratio, with positive drainage samples implicating alley 6. Since a lab leak has no explanation for positives clustering on the specific wild-animal shop, Stansifer notes this “arguably” has a Bayes factor of 15 in favor of Z. However he excludes it from his Bayesian total on principle: it is not an essential component of the zoonotic hypothesis, and in isolation is not so strong as to rule out coincidence (it is very post hoc). Recording his reasoning: he chose to include only evidence that is either an essential step of one hypothesis or independently very strong, and this within-market spatial signal fails that bar despite pointing toward zoonosis. (Descriptively discusses the China CDC market-environmental data, whose evidential weight is carried by the primary market-sampling sources, not by this adjudication node.)
Validity assessment
Reconstruction. Two steps: (i) conditional evidential claim — positives concentrating on the specific live-wildlife shop 6:29 (5 positives; 12 of 15 well-sampled shops none) is explained by Z but not by LL, so “arguably” BF ~15 for Z; (ii) methodological exclusion — set it aside because it is not an essential step of either hypothesis and not independently strong enough to rule out coincidence (very post hoc).
Evaluation (checked). Step (i) is a valid conditional given its premises (spatial clustering on a wild-animal shop being unexplained by a lab origin does favour Z). The obvious undercutting defeater — human deposition or human-traffic contamination could concentrate positives at a busy shop regardless of animal source (A-31/A-33/A-34/A-49/A-55) — would break the “LL has no explanation” premise. But the statement does not assert the BF; it hedges to “arguably” and explicitly labels the signal “possibly-coincidental, post-hoc,” and step (ii) removes it from the total. So the defeater is already priced into the hedge rather than left to overturn an asserted conclusion; the node over-claims nothing. Step (ii) is a defensible methodological choice, not an inference that can be invalid. No surviving defeater against what is actually claimed. Approved; the logic and the exclusion rationale are traced directly, hence checked.