Wright's law: unit cost falls a constant fraction with every doubling of cumulative production

economicswrights-lawlearning-curveexperience-curveprice-dynamicsresource-economics

Wright's law — also called the experience curve or learning curve — states that as cumulative production of a good doubles, its unit cost falls by a constant percentage, the "progress ratio": "if the progress ratio is 0.8 ... the unit cost is 80% of what it was before" each time cumulative output doubles. Under competition, price tracks cost down continuously across the whole scaling trajectory, rather than holding at an old level until a late collapse.

This is the proposed general mechanism behind two documented monotonic-decline cases: claim-aluminium-price-fell-monotonically-after-hall-heroult (Hall-Héroult aluminium, 1880s–90s) and claim-inference-cost-collapsed-280x (AI inference, 2022–2024). It is the structural opposite of the hold-then-collapse shape predicted for asteroid-mined platinum-group metals in claim-asteroid-pgm-price-holds-then-collapses — see claim-cheaper-extraction-disruptions-fall-monotonically-not-hold-then-collapse for the synthesis across all three.

[unverified-mechanism — needs primary] — resolved 2026-09-05. This note originally rested only on two secondary explainers (New Things Under the Sun, Our World in Data), not the originating economic literature. T.P. Wright's 1936 paper itself has now been located and read directly, confirming both that the paper is real and correctly cited and that its own formula matches this note's core mechanism — cost as a log-log-straight-line function of cumulative production quantity, not calendar time. The Boston Consulting Group's own 1960s–70s studies remain unfetched (a further lead, not a blocking gap now that Wright's own paper anchors the mechanism). question-verify-wrights-law-primary-source is marked answered on this basis.

One imprecision survives the primary check: this note's own title, like both secondary restatements, says "unit cost." Wright's own definition is over the average cost of a whole production lot, not an individual unit — a real specification gap between the popular shorthand (including this note's) and the 1936 original, though the two converge at large quantities. And the flat single percentage this note implies is itself a simplification: Wright reported four different curves for labor, raw material, purchased material, and the whole airplane, the last of which is not even constant.