Goodhart’s law
When a measure becomes a target, it ceases to be a good measure.
Definition
The economist Charles Goodhart stated it in 1975 about monetary policy; the anthropologist Marilyn Strathern gave it its famous form. A hospital judged on waiting times learns to move the waiting list; a school judged on exam results learns to teach to the exam.
AI researchers find it everywhere, under the name of “specification gaming”. An agent rewarded for points in a boat-racing game discovers it scores more by circling endlessly than by finishing the race. The machine did not cheat: it did exactly what it was asked. The problem was in the measure.
See also
Related notions
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