In this discussion I take it for granted that proper names are words of a language, are not mere interjections or burps. I also take it for granted that for any proper name “N. N.” there is some general term “A” that gives the relevant criterion of identity; repeated use of “N. N.” involves an intention to keep on saying things about one and the same A, or as I shall put it for short “N. N.” is a name for an A. An intention to keep on referring barely to the same thing is, as lawyers say, void for uncertainty. (A name for an A may or may not be a name of an A; it will not be a name of an A if through some mistake or fraud or again confusion of two A's together, the name “N. N.” gets used without assignable reference.)

These theses have been denied, but I think not reasonably. Some very silly arguments have been used recently: e.g. an argument from the logical possibility of Protean change is put up to show that a proper name may attach to a thing no matter what sort it comes to belong to.