Q. When a proper name begins a sentence, is it always capitalized, even when it’s a name commonly seen as lowercase (e. e. cummings, for example)? I’m also unclear about names with particles. CMOS 8.7 says de (or d’) is always lowercased and is often dropped when the surname is used alone. How would I know that it’s dropped from Tocqueville but not from de Gaulle if neither of these names were in Merriam-Webster?
A. E. E. Cummings can be safely capitalized—not necessarily because he’s no longer around to object, but because it wasn’t his personal preference to lowercase his name (Encyclopaedia Britannica, s.v. “Cummings, E. E.”). For those who do have a strong preference—bell hooks is a well-known example—you will want to respect it. This makes life difficult, however, for those of us who cannot bear to begin a sentence with a lowercase letter. CMOS forbids so doing (except for names like eBay)—we advise you to rewrite. Some publications simply ignore the preference (see Elise Harris, “That 4-Letter Word,” review of All about Love, by bell hooks, New York Times, January 30, 2000). Note that I’ve in turn ignored the capitalization in the Times’s review.
As for the particle de/d’, dropping it or not when referring to the surname only is a matter of tradition. If you are unable from any source to determine what that tradition might be, err on the side of retaining the particle.