The claim that Jevons was 'fascinated by' Chrysippus's dog 'because it provided an example for the mechanisation of logic' is Barrett and Connell's interpretive reading, not a line in Jevons's own text — and it is the origin of the vault's original unsourced bridge

jevonschrysippushistory-of-computinghistoriographyinterpretationdisjunctive-syllogismprovenance-tracing

The through-line the vault once asserted — that Jevons admired Chrysippus's three-road dog as a model for mechanizing inference — traces to a single named secondary source: Lindsay Barrett and Matthew Connell's history-of-computing essay "Jevons and the Logic 'Piano'" in the Rutherford Journal. Their essay states, in these words, that "Jevons was fascinated by Chryssipus' image of the logical dog because he saw precisely the way in which it provided an example for the mechanisation of logic as the basis of an intelligent machine."

Part of what the essay says is confirmable against the primary record: it reports that Jevons "uses it conclude the first chapter of Pure Logic" (sic — their wording), and a direct read of that text confirms the placement but not the chapter: the quotation closes Chapter XI, "Of Indirect Inference" (§136, pp. 47–48 of the 1890 reprint — the very pages the essay's own footnote cites), not the first chapter (claim-jevons-quoted-chrysippus-dog-in-pure-logic-1864). The chapter slip is small but worth recording in a note whose whole point is how this essay's readings traveled. But the causal clause — why Jevons quoted the dog, and that he saw it as an example specifically for mechanization — is Barrett and Connell's synthesis, offered without a supporting Jevons quotation of their own. It sits alongside the primary record, not inside it, and it points the opposite way from Jevons's own machine-justifying paper, where the ancient syllogism is called crude and Boole gets the credit (claim-jevons-1870-paper-credits-boole-not-ancients-for-mechanizable-logic).

Correctly held at Tier 2: a named scholarly retelling's interpretation of authorial motive, not Jevons's own words, and not to be promoted as if it were primary. This note is also the provenance receipt for how an unsourced bridge entered the vault in the first place — the elimination through-line inherited Barrett and Connell's causal reading without their attribution, and this session finally names where it came from.