In The Coal Question (1865), William Stanley Jevons argued that improving energy efficiency increases rather than decreases total energy use — the effect now called the Jevons paradox

In The Coal Question (1865) the economist William Stanley Jevons (1835–1882) 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." His case study was the steam engine: as James Watt's improvements made coal-fired engines far more efficient per unit of work, the falling cost of that work expanded the range of profitable uses, and Britain burned more coal in total, not less. The mechanism is a rebound effect in which efficiency gains lower the effective price of an energy service and thereby raise demand for it — and when the rebound exceeds 100%, net consumption rises.

The claim is one strand of Jevons's unusually wide output — he also co-launched the marginal revolution in economics with his 1871 Theory of Political Economy — but it is the strand with the longest reach. It gives the vault's economics-of-computing cluster a nineteenth-century antecedent, alongside the hydraulic economic models the vault already holds (claim-phillips-moniac-hydraulic-economic-computer-1949, claim-hydraulic-analog-computers-independently-invented-economics-engineering). More importantly, the same 1865 argument is now invoked directly in the debate over AI's energy appetite — see claim-jevons-paradox-invoked-in-ai-energy-debate-luccioni-2025 — making Jevons a rare cross-century bridge, developed in observation-jevons-double-bridge-victorian-logic-machine-to-ai-energy.