William Stanley Jevons is a double bridge from Victorian logic to modern AI — he built an early logic machine AND coined the efficiency paradox now framing AI's energy appetite

The chain that started at Peirce's abduction ended on a single Victorian polymath, William Stanley Jevons (1835–1882), who turns out to sit at the root of two separate threads of modern computing — a rare double cross-time bridge.

Core claims

1. Jevons built an early mechanical logic machine — the "Logic Piano." A "'logical machine' built from his specifications in 1869, sometimes called the 'Logic Piano' because of its resemblance to an upright piano," exhibited before the Royal Society in 1870. It mechanically performed logical inference — the same lineage that Allan Marquand extended and that Peirce, in his 1886 letter to Marquand, proposed moving onto electrical switching circuits half a century before Shannon's 1937 thesis. (Wikipedia, Tier 4 — biographical/uncontested.)

2. The same man coined the efficiency-rebound paradox. In The Coal Question (1865) Jevons argued that "improving energy efficiency typically reduced energy costs and thereby increased rather than decreased energy use, an effect now known as the Jevons paradox." (Wikipedia, Tier 4.)

3. That 1865 paradox is now load-bearing in AI's energy debate. Luccioni, Strubell & Crawford (FAccT 2025) invoke it directly: "just because an AI model becomes more efficient, that does not imply that overall AI resource consumption will decrease, and in fact the inverse effect is highly plausible." (arXiv:2501.16548, Tier 1.)

Why this was hop-worthy

One Victorian economist-logician is simultaneously an ancestor of the logic machine (proto-computer) lineage and the author of the efficiency paradox now used to explain why more-efficient AI chips may consume more total energy. The vault already holds both endpoints separately (inference-engine / logic-machine notes; economics-meets-computing notes like MONIAC and hydraulic analog computers) — Jevons links them.

Further leads

• Allan Marquand: proto-computer-scientist redirected into art history by Calvinist orthodoxy — its own capture-worthy story.
• Marquand diagrams as precursors to Venn diagrams / Karnaugh maps.
• The DeepSeek-era (early 2025) revival of "Jevons paradox" as AI-industry talking point — who invoked it and why.

Hop chain

Seed: claim-inference-logical-types.md (vault note) — Peirce named/theorized abductive inference. Left the topic immediately (inference typology → the person Peirce).

Hop 1: Peirce recognizes logic could run on electrical switching circuits — historyofinformation.com / history-computer.com. Hook type: cross-domain / cross-time bridge (1886 logician → digital hardware). Why followed: confirmed vault bridge_candidate sitting in the Faggin / Harold-Black / hydraulic-computer cluster — the spec's highest-value hook. Key findings: In a 30 Dec 1886 letter to former student Allan Marquand, Peirce proposed electricity/relays for logic machines, ~50 years before Shannon's 1937 thesis made switching-circuit logic canonical.

Hop 2: Allan Marquand — Wikipedia / History-Computer. Hook type: person behind the thing + surprising claim. Why followed: the man who built the machine has a stranger story than the machine. Key findings: Princeton president James McCosh deemed Marquand's mathematical logic teaching "unorthodox and uncalvinistic"; in 1883 Marquand was moved to the first art-history professorship and became the founder of Princeton's Department of Art and Archaeology and first director of its art museum. The proto-computer-scientist became American academic art history's founder.

Hop 3: William Stanley Jevons — Wikipedia. Hook type: person / cross-domain bridge. Why followed: Marquand's machine was inspired by Jevons' "Logical Piano"; the source of the lineage was worth meeting. Key findings: Jevons built the 1869 Logic Piano and wrote The Coal Question (1865) and co-launched the marginal revolution in economics (1871) — a triple polymath.

Hop 4: Jevons paradox in AI's environmental debate — Luccioni, Strubell & Crawford, FAccT 2025 (arXiv:2501.16548). Hook type: cross-time-period bridge landing on AI (road home). Why followed: the 1865 coal paradox is being used to argue AI efficiency gains raise, not lower, total energy demand. Key findings: the rebound effect can exceed 100%; the authors cite NVIDIA shipping 3.7M GPUs in 2024 despite per-unit efficiency gains. Natural stop reached.

Saved hooks not followed:

• Marquand's "uncalvinistic" exile into art history — Wikipedia — a self-contained surprising-claim capture; deferred to keep this thread on the Jevons bridge.
• James McCosh, Scottish Common Sense realist who both accepted Darwin and policed "uncalvinistic" logic — Wikipedia — a person hook on the theology-vs-formal-logic tension.
• Marquand diagrams → Venn/Karnaugh map lineage — mechanism hook, likely near existing logic notes.

Surprise: expected the abduction thread to stay in philosophy of logic — found it runs straight into digital hardware via Peirce's 1886 electrical-switching proposal. Surprise: expected the builder of an early logic machine to have stayed in logic/computing — found Allan Marquand was pushed out for being "uncalvinistic" and became the founder of American academic art history. Surprise: expected the Logic Piano and the Jevons paradox to be two different people's work — found the same man (Jevons) authored both, making him a double bridge to modern AI.

post-worthy: yes — a single Victorian polymath secretly underwrites both the logic-machine ancestry of computers and the efficiency-paradox now framing AI's energy bill; the Marquand "uncalvinistic" detour is a bonus hook for a follow-up.