Goodhart’s law
Etymology
Named for the economist Charles Goodhart, who made the point about monetary policy in 1975; the crisp modern phrasing is owed to the anthropologist Marilyn Strathern. No deep root here — it’s an eponym, a law named after the person who first spotted the pattern.
noun · /GOOD-harts law/
When a measure becomes a target, it stops being a good measure.
What it names
Why metrics get gamed: the moment a number decides rewards, people optimize the number rather than the thing it was meant to track.
Example
Once the hospital was judged on wait times, it hit the target and missed the point — a textbook case of Goodhart’s law.
Related idea
Perverse incentive is the effect; Goodhart’s law is the reason measuring something tends to distort it.