William Stanley Jevons

Victorian English economist and logician (1835–1882) who both built one of the first working machines to mechanically perform deductive inference and formulated the efficiency-rebound argument that now bears his name. He first entered this vault on 2026-07-12 (his logic machine and his coal-efficiency argument arriving as separate research threads) but had no dedicated hub until this pass, despite recurring as the named subject of six notes across two unrelated clusters.

Matters to this vault as a genuine double bridge into modern AI. Engineering leg: the "Logic Piano" (1869), physically mechanizing Boolean deduction and citing both Boole and Babbage as intellectual forebears — claim-jevons-logic-piano-1869-mechanical-inference-machine, dated precisely by claim-jevons-1870-paper-received-16-oct-1869-read-20-jan-1870-royal-society and independently corroborated by claim-oxford-history-of-science-museum-catalog-dates-jevons-logic-machine-to-1869. Economic leg: The Coal Question (1865) argued that efficiency gains raise, not lower, total resource use — claim-jevons-paradox-coal-question-1865-efficiency-rebound — an argument now invoked verbatim in AI's energy debate (claim-jevons-paradox-invoked-in-ai-energy-debate-luccioni-2025). See observation-jevons-double-bridge-victorian-logic-machine-to-ai-energy for the synthesis of both legs.

References

• claim-jevons-logic-piano-1869-mechanical-inference-machine

• claim-jevons-1870-paper-received-16-oct-1869-read-20-jan-1870-royal-society

• claim-oxford-history-of-science-museum-catalog-dates-jevons-logic-machine-to-1869

• claim-jevons-paradox-coal-question-1865-efficiency-rebound

• claim-jevons-paradox-invoked-in-ai-energy-debate-luccioni-2025

• observation-jevons-double-bridge-victorian-logic-machine-to-ai-energy

• 2026-08-10: A direct read of Jevons's own logical writings settled whether he engaged Chrysippus's three-road dog — he quoted it verbatim (in Sir Walter Raleigh's wording) to close his exposition of "indirect inference" in Pure Logic (1864) (claim-jevons-quoted-chrysippus-dog-in-pure-logic-1864), and derived the logic machine from that same elimination principle in The Substitution of Similars (1869) (claim-jevons-derived-logic-machine-from-indirect-inference) — but in his 1870 Royal Society paper he credits Boole and 19th-century reform, not the ancients, for making mechanization possible (claim-jevons-1870-paper-credits-boole-not-ancients-for-mechanizable-logic)

• 2026-09-30: Jevons also enters this vault as the target of another logician's direct critique, independent of both bridges above — Herbert Austin Aikins's 1902 Principles of Logic names and quotes Jevons's stated conversion rules and eight numbered "rules of the syllogism" verbatim, by page number, in two separate chapters (Ch. XI, Ch. XVI), then argues in his own words against rule-following as a method — before ever reaching the shared jingle-fallacy chapter (Ch. XVIII) the vault had already captured. See claim-aikins-1902-ch11-quotes-jevons-conversion-rules-verbatim-then-rejects-rule-following, claim-aikins-1902-ch16-footnote-quotes-jevons-eight-syllogism-rules-verbatim-then-rejects-them, and claim-aikins-1902-preface-states-program-of-replacing-jevons-style-syllogism-rules-with-principles. Which of Jevons's own texts supplies the exact page numbers Aikins cites is not yet confirmed — see question-verify-aikins-1902-jevons-source-edition-for-conversion-and-syllogism-rules.

• 2026-10-01: That open question is now settled — a direct read of Jevons's own Elementary Lessons in Logic (1870; the 1881 Macmillan "New Edition," via Darwin Online) confirms Aikins's "Jevons, p. 82"/"p. 83" and his eight numbered syllogism rules trace, word for word, to Lesson X and Lesson XV of this specific book, with the printing's own table of contents independently fixing the pagination. See entity-elementary-lessons-in-logic-jevons and claim-jevons-elementary-lessons-lesson-x-source-of-aikins-conversion-rule-citations.

• 2026-10-11: The same book Aikins quotes to the page also contains, sixty to seventy pages later (Lesson XXIII, "Boole's System of Logic," pp.191–201), an explicit description of the Logic Piano's keyboard and a citation to its own 1870 Royal Society debut — not a separate technical paper Aikins would have had no reason to see. This closes the "machine arrived too late/elsewhere for Aikins's source" reading of his silence; the remaining account is structural (the machine sits under a thematic heading Jevons himself calls "recent," two blocks past the traditional-syllogism material Aikins actually quotes) rather than bibliographic. See claim-jevons-elementary-lessons-lesson-xxiii-describes-logic-piano-and-its-royal-society-debut, claim-aikins-engagement-with-jevons-tracks-traditional-syllogism-block-not-booles-system-block, and the grading in claim-aikins-silence-on-jevons-logic-piano-is-weak-on-mcgrew-record-term-not-notice.