Campbell's Law
The adage that "the more any quantitative social indicator is used for social decision-making, the more subject it will be to corruption pressures and the more apt it will be to distort and corrupt the social processes it is intended to monitor."
EverydayConcepts.io
Origin
Articulated by Donald T. Campbell (1916–1996), an American social psychologist at Northwestern University. He formalized the principle in a 1976 paper titled 'Assessing the Impact of Planned Social Change,' drawing on case studies in social policy evaluation to warn that any metric used for decision-making will eventually be corrupted.
Updated February 22, 2026