CODEXCard 2 of 9 · Modern Internet Patterns
Goodhart's law
When the metric becomes the target, the metric stops measuring what it measured.
Goodhart's law is the observation that a measure loses its value once people treat it as a target. It is named after the British economist Charles Goodhart, who made the point about monetary policy in the 1970s. The short version most people quote today comes from the anthropologist Marilyn Strathern.
The mechanism is simple. A metric starts as a rough signal of something we care about. Views might hint at interest, likes at quality. Once creators and platforms are rewarded for raising the number, they find ways to raise it that have nothing to do with the original goal: provocative thumbnails, bait headlines, content tuned for clicks. The number climbs while the thing it tracked drifts away.
The mistake is deciding that all metrics are worthless. Many measures work well, especially when nobody is under pressure to inflate them. Goodhart's law names a particular failure that appears when a number becomes the thing people are paid, ranked or praised for. The useful response is to watch for that shift and pair any key metric with direct checks on the real goal.
This pattern sits close to Charlie Munger's point about incentives. Whatever a system rewards, people will deliver, including the side effects nobody intended.
Example
A school starts ranking teachers by how many students pass a yearly test. Over time, lessons shift toward drilling the exact question types on the test, and pass rates rise. Yet students struggle more when they meet a slightly different problem. The score improved while the learning it was supposed to show did not.
Try it this week
Pick one number you track at work or at home this week and ask what behaviour it rewards that you do not actually want.
From Modern Internet Patterns (Internet Theory).
