Citation, Documentation of Sources

Q. My joining your site was prompted by entry 8.40, “Centuries and Decades,” of your 14th edition. Your sample decades were 1800–1809 and 1910–19, and those examples make no sense to me. Decades must have ten years; decades can’t skip years; decades can span neither millennia nor centuries as you have them doing in your examples; e.g., 1800 is the last year of the 18th century, not the first year of the 19th century, and the second decade of the 20th century is 1911–20, not 1910–19. I don’t want to get off on the wrong foot, but isn’t precision an essential ingredient in all writing before style considerations? Also, should writing style be based on popular culture rather than logic? I’m troubled by this entry in your manual and I’d appreciate your letting me know how you justify it.

A. Welcome to CMOS 17 (and the twenty-first century)! As any linguist will confirm, in both grammar and style matters, convention often outweighs logic, and there is little to be done about it. If you decide to start a campaign to impose logic on the designation of decades and millennia, we wish you well. In the meantime, you’ll be happy to know that, as of the 15th edition, CMOS acknowledges your system: “Note that some consider the first decade of, for example, the twenty-first century to consist of the years 2001–10; the second, 2011–20; and so on. Chicago defers to the preference of its authors in this matter.”