Words

Rule of Thumb

rool uhv THUM
The claim that rule of thumb comes from an old law permitting a man to beat his wife with a stick no thicker than his thumb is false. No such law existed. The phrase means a rough practical measure, and the wife-beating version is a modern error with a complicated life of its own.
Documented

Documented

Rule of thumb for rough-and-ready practice is attested from the 1690s, with the thumb as a natural unit. No English or American statute, case, or treatise ever established a thumb-thickness standard for wife-beating; the 1782 Buller caricature is the earliest known source of the association, and it was satire. Christina Hoff Sommers publicized the debunking in the 1990s, and legal historians have confirmed no such rule existed.

Assessment: Documented in the OED, the Buller cartoon record, and the legal-historical literature; the wife-beating origin is classified as false by the standard references.
Stories

Stories

The claim circulated in feminist texts of the 1970s and 80s as an example of law's historical cruelty, and its debunking was then weaponized by the opposite camp as proof that feminists invent history. Both camps had a point to make; the phrase itself had neither. Domestic cruelty was real and under-prosecuted, but this phrase was never its legal basis.

Assessment: The error's political biography is documented and worth more than the error itself.
Interesting claims

Interesting claims

The archive's verdict on the pattern: a false etymology can carry a true charge, which is why false etymologies survive debunking. The cure is not silence but labeling, say what is documented, say what is believed, say what is merely useful to believe.

Assessment: This card is the method page wearing a word costume.
Sources and further reading
  1. OED, rule of thumb, attested from the 1690s, rough measure
  2. The 1782 James Gillray-era caricature of Judge Buller as Judge Thumb
  3. Sommers, Who Stole Feminism (1994), and legal-historical confirmations that no thumb law existed
Worth asking

A myth about a law became more famous than any law. When we repeat a debunked origin to make a real point, what are we actually saying?

Open in the interactive archive
GR8YFILES · competing origin stories, labeled by the strength of their evidence · readers 14+