rule of thumb

there has been much debate about this term and its association with the right of a man to chastise his wife with a switch no thicker than his thumb. The original "rule of thumb" had nothing to do with wife-beating (among the provenances: the last joint of the thumb is about an inch and so was commonly used as a measure; artists used a thumb to gauge perspective; the thumb was used to test the degree of fermentation of malt in making beer in 19th-century England; the thumb was used as a tiny writing pad to calculate the exchange of Spanish dollars for French francs by French contractors in the early 1800s in southern France). In "Rule of Thumb and the Folklaw of the Husband's Stick," Journal of Legal Education, Henry Ansgar Kelly writes, "Printed references to 'rule of thumb' as a guideline antedate references to it in the context of wife-beating by almost several hundred years. An 1868 case, State v. Rhodes appears to be the only case on record in which a husband was let off because 'His Honor was of opinion that the defendant had a right to whip his wife with a switch no larger than his thumb.'" Kelly points out that the verdict was overturned by State v. Oliver (1874): "We may assume that the old doctrine, that a husband had a right to whip his wife, provided he used a switch no larger than his thumb, is not law in North Carolina. Indeed, the Courts have advanced from that barbarism until they have reached the position, that the husband has no right to chastise his wife, under any circumstances." The overturning of the case apparently got less press than the original suit. In 1881, Harriet H. Robinson (Massachusetts in the Woman Suffrage Movement) wrote, "Thirty years ago, when the Woman's Rights Movement began, the status of a married woman was little better than that of a domestic servant. By the English common law, her husband was her lord and master. He had the sole custody of her person, and of her minor children. He could 'punish her with a stick no bigger than his thumb,' and she could not complain against him." In Margaret Deland's 1924 New Friends in Old Chester, a woman said to the man who had "jokingly" threatened to beat her, "Let's see ... you can use a stick no bigger than your thumb, can't you?" "Rule of thumb" may not have originated in wife-beating, but it has acquired that association for many people. Use instead: general rule, rough guideline, commonsense/ballpark/approximate measure.