Where the law comes from

Charles Goodhart, an economist advising the Bank of England, made the point in 1975 about money. In the early 1970s the Bank tried to steer the economy through measures of the money supply, and relationships between those figures and the wider economy, which had looked stable, stopped holding. A statistical pattern, he observed, tends to break down once you lean on it to control things.

The anthropologist Marilyn Strathern later gave it the wording most people quote: when a measure becomes a target, it ceases to be a good measure. The psychologist Donald Campbell reached much the same conclusion about social policy in the 1970s.

A recommendation feed is this kind of measure. It ranks posts by what it can count, such as clicks, replies and time spent, and everyone who posts learns to raise the count. As with the observer effect in physics, measuring changes what is measured. The sociologists Wendy Espeland and Michael Sauder called this reactivity, after watching law-school rankings remake the schools they ranked.

Why a glen

In the Highland Clearances, landlords emptied townships to make way for sheep, because sheep paid better than tenants. Here the sheep are posts made only to grab attention. Under the platform's feed they pay better than posts worth reading.

The question is whether giving people control of their own feeds keeps a community whole when someone else owns the default.

Try this

1. Press Reset the glen and leave the slider at 3%. Watch for a minute. Creators learn that grabbing attention pays. Sheep fill the glen, windows go dark and roofs fall in.
2. Press 70% and choose 1 feed. The townships hold, but creators learn to game that one feed's measure instead. Grey cairns appear on the hills.
3. Now choose 6 feeds. Each feed rewards something different, so gaming any one of them pays little. The only thing that scores well everywhere is a post worth reading.