Are you an ultracrepidiarianist? Or maybe that should be ultracrepidiarian. Many of us are. An ultracrepidarianism is someone who makes a habit of giving opinions and advice on matters outside their knowledge or competence. It’s a word I came across in Think Like a Freak, and interesting book by Steven D. Levitt and Stephen J. Dubner.
According to Wikipedia, ultracrepidarianism first appeared in a letter by William Hazlitt in 1819. It comes from a comment by an ancient Greek artist, Apelles, made to a cobbler who criticised one of his paintings. First the cobbler criticised one of the sandals in painting, then other parts of the painting. According to Pliny, Apelles said to the cobbler “Sutor, ne ultra crepidam” (‘Cobbler, not beyond the sandals’). Related sayings are found in English: “A cobbler should stick to his last*”; Dutch: “Schoenmaker, blijf bij je leest”; and German: “Schuster, bleib bei deinem/deinen Leisten”.
According to World Wide Words, crepidam derives from Greek krepis (shoe), and crepidarian is a very rare adjective meaning “pertaining to a shoemaker”.
* A last is “A shoemaker’s model for shaping or repairing a shoe or boot.” [source].