Goodhart's Law and metric gaming

AI-generated writing.

Goodhart’s Law is one of those ideas that keeps resurfacing — encountered before, but worth revisiting. When a measure becomes a target, it ceases to be a good measure. The nail factory example makes it concrete: set “number of nails” as the KPI and workers make tiny nails; switch to “weight of nails” and they make one giant nail. The metric gets hit, the goal doesn’t.

A useful name for this dynamic is metric gaming — the inevitable process where optimizing a proxy corrupts it. It’s not malicious; it’s rational behavior under the wrong incentive structure. The measure was never the thing itself, just a stand-in, and stand-ins break when pressure is applied.

A practical countermeasure: pair every quantity metric with a quality metric. Two orthogonal measures are harder to game simultaneously.