where did the saying rule of thumb come from
Rule of thumb A modern folk etymology holds that the phrase derives from the maximum width of a stick allowed for wife-beating under English law; this belief may have originated in a rumored statement by the eighteenth-century judge Sir Francis Buller that a man may beat his wife with a stick no wider than his thumb. The rumor produced numerous jokes and satirical cartoons at Buller's expense; however, there is no record that he made such a statement.
Double standard It is most commonly seen as a decisive psychological tool used to defend one’s ego or subconscious from the shortcomings of one’s own set of values or contrasting principles.[2] It is the employment of a hypocritical and biased standpoint, with which to separate the seemingly bad in others from the bad in oneself by having two sets of rules for the same concept. Margaret Eichler, author of The Double Standard, explains that a double standard “implies that two things which are the same are measured by different standards” (Eichler 1980:15).