The Default Outcome Is No Change

Definition

Weinberg calls this "Weinbergs' Law of Twins": "Most of the time, for most of the world, no matter how hard people work at it, nothing of any significance happens." For nearly any system, the single best prediction of its state one moment from now is simply its current state — change is the rare exception against a heavy background of persistence, and this holds regardless of the effort being applied to produce change.

In the Book

The insight is triggered by an overheard exchange on a New York City bus: a driver, seeing a woman board with eight small children, assumes she must have several sets of twins; she corrects him — "Most of the time we don't have any [twins]." Weinberg and his wife, fresh from a frustrating consulting engagement where nothing they did seemed to change anything, recognize the pattern: most attempts at significant change, most of the time, fail to produce significant change, in exactly the same way that most pregnancies don't produce twins. He offers a direct test — close your eyes for a minute, open them, and notice that almost everything is unchanged — and notes the law's reach: "planets and polymers, porcelains and peonies, parliaments and pajamas... And, best of all, to people!" He is candid that the law disappointed people expecting a psychological law to explain how to produce change; instead it explains why so much change effort yields nothing.

Why It Matters

This supplies the base rate against which any claimed intervention effect must be measured: before crediting a consultant, a policy, or a personal effort with producing change, the live alternative hypothesis is that nothing would have happened regardless. It's the same discipline evaluation and causal-inference work insists on — a control condition — applied informally to daily judgment, and it explains why unmeasured "successes" are so often illusory: absent a real comparison to the default (no significant change), almost any outcome can be misread as the effort having worked.