Rule of thumb: Don’t believe folk etymologies
by
Howard Richler
I’d been getting together weekly
with a group of friends for around a year where we indulge in some banter whist
scoffing croissants and imbibing varieties of java. We originally called these
meetings “The Summit” but after several
months of not coming close to solving any world problems and owing up to the
mundane nature of our discussions we re-dubbed it “the swamp.” In any case, one time
during one of our rare erudite sessions, we must have discussed some language
issue, because a lady came over to our table and said she was listening to our language
bavardage and asked whether we knew that the origin of the expression “rule of
thumb” came about to dictate the legal length of an object a man could use in
order to beat his wife. Alas, I had to
disabuse of as to the veracity of this explanation.
Mind you, this myth is oft
repeated. Take the following explanation found in Women: A Feminist Perspective, edited by Jo Freeman: "The
popular expression 'rule of thumb' originated from English common law, which
allowed a husband to beat his wife with a whip or stick no bigger in diameter
than his thumb. The husband's prerogative was incorporated into American law.
Several states had statutes that essentially allowed a man to beat his wife
without interference from the courts."
In the 1980s, Time magazine wrote, “The colloquial
phrase ‘rule of thumb’ is supposedly derived from the ancient right of a
husband to discipline his wife with a rod ‘no thicker than his thumb,’ ” and in
1989 Washington Post added, “A husband's
right to beat his wife is included in the 1768 codification of the common law.
Husbands had the right to ‘physically chastise’ an errant wife so long as the
stick was no bigger than their thumb - the so-called ‘rule of thumb’”.
Actually, nobody has been
able to find a single English or American law that ordains this conjugal thumb
right to a husband. It has been claimed
that in 1782 British judge Sir Francis Buller proclaimed that a husband may
beat his wife with a stick not thicker than his thumb but nobody has been able
to discover documentation of such. On the contrary, 18th century
British and American law prohibit wife
beating (though often this provision was only casually enforced.)
That the phrase did not
originate in legal practice is verified by the “rule of thumb” entry in the OED:
“A method or procedure derived entirely from practice or experience, without
any basis in scientific knowledge; a roughly practical method. Also, a
particular stated rule that is based on practice or experience.” The first citation is from 1658: “Many
profest Christians are like foolish builders who build by guess and by rule of
thumb.”
The expression probably comes from the world
of wood-working where ancient practitioners would rarely use rulers but would
measure things by the length of their thumbs. It’s most likely that the saying
comes from the length of the first joint of the thumb, which measures
approximately one inch. An alternate theory, posited by other etymologists,
credits the origin with brewmasters who often tested the temperature of the
beer (before the invention of the thermometer by dipping a thumb in the brew. This
seems unlikely to me as the thumb is not that sensitive and the fermentation
range between too warm and too cool is not appreciable.
In a subsequent column, I’ll
look at some other folk etymologies.
Richler’s latest book is Wordplay: Arranged and Deranged Wit
