Rule of thumb

In English, the phrase rule of thumb refers to an approximate method for doing something, based on practical experience rather than theory.^[1]^[2]^[3] This usage of the phrase can be traced back to the 17th century and has been associated with various trades where quantities were measured by comparison to the width or length of a thumb.

An erroneous folk etymology began circulating in the 1970s falsely connecting the origins of the phrase "rule of thumb" to legal doctrine on domestic abuse. The error appeared in a number of law journals, and the United States Commission on Civil Rights published a report on domestic abuse titled "Under the Rule of Thumb" in 1982. Some efforts were made to discourage the phrase, which was seen as taboo owing to this false origin. During the 1990s, several authors correctly identified the spurious folk etymology;^[4] however, the connection to domestic violence was still being cited in some legal sources into the early 2000s.

^ Cite error: The named reference OED was invoked but never defined (see the help page).
^ Cite error: The named reference Wordsworth was invoked but never defined (see the help page).
^ Cite error: The named reference Clapp was invoked but never defined (see the help page).
^ Kelly, Henry Ansgar (1994). ""Rule of Thumb" and the Folklaw of the Husband's Stick". Journal of Legal Education. 44 (3): 341–365. ISSN 0022-2208. JSTOR 42893341.

[OED-1] Cite error: The named reference OED was invoked but never defined (see the help page).

[Wordsworth-2] Cite error: The named reference Wordsworth was invoked but never defined (see the help page).

[Clapp-3] Cite error: The named reference Clapp was invoked but never defined (see the help page).

[4] Kelly, Henry Ansgar (1994). ""Rule of Thumb" and the Folklaw of the Husband's Stick". Journal of Legal Education. 44 (3): 341–365. ISSN 0022-2208. JSTOR 42893341.

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