Jevons Paradox

The Jevons paradox is the observation that improvements in the efficiency with which a resource is used tend to increase, rather than decrease, the total consumption of that resource. It was first articulated by William Stanley Jevons in his 1865 book The Coal Question, in the chapter "Of the Economy of Fuel." Jevons noted that James Watt's improvements to the steam engine had dramatically reduced the coal required per unit of mechanical work. Conventional intuition predicted that Britain would therefore burn less coal. Instead, coal consumption rose sharply, because the cheaper effective price of motive power expanded the set of industries in which steam was profitable — railways, ironworks, textile mills, shipping, mining itself. Jevons wrote that it was "a confusion of ideas to suppose that the economical use of fuel is equivalent to diminished consumption." The paradox is closely related to, but stronger than, the modern Rebound Effect (Energy Economics). The rebound effect describes any partial offset of efficiency-driven savings; the Jevons paradox specifically refers to the case in which the offset exceeds 100% — efficiency gains cause net increases in resource use. Economists Daniel Khazzoom and Leonard Brookes generalized this idea in the late 20th century, and Harry Saunders dubbed it the Khazzoom-Brookes postulate in 1992. The paradox is invoked frequently in contemporary debates: efficient lighting and LED adoption, fuel-efficient vehicles and induced demand for travel, and most recently AI compute, where falling per-token inference costs appear to expand total compute usage. It is not universal — at some point demand saturates — but it is a standard warning against assuming that efficiency alone reduces aggregate consumption.