The Misunderstood 'Rule of Thumb' Misconception: For years many feminists thought that the term 'rule of thumb' referred to the British common law tolerance of hitting women. (2023)

Sharon Fenick first heard the phrase "rule of thumb" being cited as sexist derogatory terms during her freshman year at Harvard seven years ago.

The phrase was cited in a lecture as an example of domestic violence permitted under British common law. The rule of thumb, the professor said, was a law that allowed a man to hit his wife as long as the stick used was no thicker than his thumb. But over the centuries, the term had become a slang term for an "approximate measure."

"It sounded very believable to me," says 24-year-old Fenick, who is now in her third year at the University of Chicago. "It was my first exposure to feminist thinking and [the statement] was very impressive to me. It was one of those things that I really remember that got around. I can't remember when I found out it wasn't true."

Unlike Fenick, countless historians, feminists, and legal experts are unaware that the folk etymology for "rules of thumb" is wrong. To them, the notion of a "rule of thumb" makes perfect sense given that it supposedly comes from a legal system they see as misogynistic.

In January, wordsmith William Safire debunked the incorrect etymology of "rule of thumb" in his New York Times Magazine column. The president of George Washington University had drawn his attention to the sentence where a student had denounced its use by an administrator who had commented on budget problems in the student newspaper.

In gender and women's studies courses across the country, the phrase is still cited as an example of unconscious acceptance and condoning of sexist politics. A computer search for the use of "rule of thumb" and "wife" in the same newspaper sentence reveals many letters to the editor in recent years from women upset by the casual appearance of the phrase in news articles. In a televised domestic violence news analysis in 1994, even commentator Cokie Roberts noted the misunderstanding.

The false etymology persists despite the Oxford English Dictionary's definition: "A method or procedure derived entirely from practice or experience, without any basis in scientific knowledge; an approximately practical method." The OED dates the first mention of the phrase to 1692.

The Encyclopedia of Word and Phrase Origins additionally defines "rule of thumb" as a method brewers once used to test the temperature of a batch of beer: they dipped a thumb into the brew.

During her freshman year of law school, Fenick, a wordsmith herself, was determined to unravel the history of the "rule of thumb." Does the sentence come from a specific rule? Was there such a rule? Even if there wasn't a rule, did a notorious judge's ruling establish "thumbstick" guidelines for would-be wife-beaters?

She discovered that while "rules of thumb" were not recognized law, there was ample evidence that the British legal system, and the American legal system that inspired it, was unkind to women. "I found that in the 19th century [women's beating] was really a topic worth discussing," she says.

Wife hitting is recognized in Blackstone's "Comments," and many court decisions sanctioned the practice. But whether the "rule of thumb" was accepted as law was another matter.

Fenick traced the earliest possible reference to the 17th century when a certain Dr. Marmaduke Coghill, an Irish judge, held that a man who had hit his wife "with a rod like the one he held in his hand" was within his marital privilege.

In the 18th century, a judge named Francis Buller, nicknamed "Judge Thumb" by the famous cartoonist James Gillray, is said to have allowed a man to hit his wife as long as the punishment stick was no thicker than his thumb. (A witty countess is said to have asked the judge to measure her husband's thumb so she could know the exact extent of his privilege.)

Fenick also found three cases from 19th-century America that mentioned the "rule of thumb", including an 1868 ruling in North Carolina that "the defendant had the right to strike his wife with a rod no larger than his thumb was".

Buller's "thumbstick" opinion and the three American judgments Fenick found were intriguing - and damning - but did not constitute definitive proof that the rule of thumb was derived from British common law.

When Fenick, encouraged by a law professor, considered publishing her findings, she found that Henry Ansgar Kelly, an English professor at the University of California, had forestalled her. His Rule of Thumb and the Folklaw of the Husband's Stick appeared in the Journal of Legal Education in September 1994.

Kelly had covered the same territory as her, much to Fenick's disappointment. (Though she proudly notes that his article missed the earliest reference to Coghill's "rule of thumb.") Three and a half years later, Safire relied entirely on Kelly's article to support his arguments in his column.

However, Fenick's efforts were not in vain. In response to a request from a correspondent for the alt.folkore.urban newsgroup, which links to the Urban Legends website, Fenick published her article where it is now part of the site's permanent archive. Since its inception, the site has broadened its mission from studying the origins and dissemination of urban legends to “confirming or refuting beliefs and facts of all kinds, including the origin of vernacular”.

"Rules of thumb" and other idioms can function similarly to urban legends: they can appear mysterious, spread spontaneously, and contain elements of humor or horror. And like urban legends, an idiom can contain a grain of emotional, if not factual, truth.

So, at first, it was easy for Fenick and others to believe that the "rule of thumb" was grounded in common law. Patricia A. Turner, a folklorist at the University of California, Davis, understands very well how a lie can take on the mantle of truth.

In I Heard it Through the Grapevine: Rumor in African-American Culture, Turner examines the ways in which claims of enforced birth control, corporate collusion with the Ku Klux Klan, drug targeting in urban areas, and other anti-Black conspiracy theories have been perpetuated in the Circulating the African American community are based on racial realities and serve as a form of resistance to white oppression.

The same theory can be applied to the rule of thumb, Turner says. A text may turn out to be inaccurate or wrong, but "if it reflects a deeper truth in society, it doesn't go away." The term "rule of thumb" may not "have this specific etymological origin, but men have dominated women in the workplace and at home and in virtually every setting. It speaks to a deeper truth."

Women's history students who may want to explore apocryphal ideas are also at a disadvantage because they "don't have the paper trail that more mainstream areas of the academic discipline have," Turner says. "Sometimes it's harder to get to the bottom of something."

However, Turner concedes that it is "very sloppy for an academic to relay misinformation." Once a theory like the inaccurate story of the "rule of thumb" is debunked, it can backfire on its proponents, she says. "If someone has read it and knows it's wrong, everything is discredited at that level. So, on the basis of a single falsehood, an entire story can be questioned.”

Concerned scholars and social critics say this happened when Christina Hoff Sommers wrote in her 1994 book Who Stole Feminism? How Women have Betrayed Women” disproved the “rule of thumb”. Sommers finds the earliest misuse of the phrase in a 1976 report by the National Organization for Women and uses it to support her arguments against domestic violence statistics.

Feminist eagerness to brandish the "rule of thumb" to justify their crusade, Turner suggests, may have inadvertently provided Sommers and her sympathizers with ideal ammunition to discredit the same cause.

Fenick received a nice letter from Kelly, who told RTC of her research after the Safire article ran. She has written him back and hopes to hear what he thinks of her Coghill reference soon.

Release date: 4/17/98