I used to dismiss Goodhart's law as trivializing measurement. After all in the oft mangled Deming Quote - what you cannot measure, you cannot manage or you cann

I used to dismiss Goodhart's law as trivializing measurement. After all in the oft mangled Deming Quote - what you cannot measure, you cannot manage or you cannot improve. I was terribly wrong and this is my mea culpa. Goodhart's can also be thought of as the notion of reflixivity or a negative feedback loop. Reliance on a measure leads everyone to optimize for it inducing fragility and in the limit breaking it. This is often seen in realms where human behavior intersects with emergent phenomenon e.g. financial markets. A metric like the sharpe ratio comes into vogue. Everyone works on optimizing (gaming) it to the point that a high sharpe ratio actually becomes a signal of impending large drawdowns. (https://twitter.com/nntaleb/status/1002622066426773504 https://twitter.com/nntaleb/status/1002622066426773504). The world is messy and we all labor under Godel Incompleteness.