Amazingly, the proudly reactionary (linguistically speaking, of course) Vocabula Review has published an article by Joan Taber Altieri (under the clever disguise of jjoan ttaber altieri) supporting the (common and much needed) use of “they/their” as a (gender-neutral) singular pronoun. Welcome to the real world, Vocabula! Of course, the imperial troops will continue fighting a rear-guard action for some time, as evidenced by this classic response from Michael Dietsch:
I accept their arguments and in principle I agree, but I’d be loath to accept this use of they in my writing or editing. The onus against it is still so strong that one who uses it, even consciously, is deemed a lesser writer for so doing. And although I know that’s silly on its face, I’ll still allow every grammarian dog to have his or her day.
The last refuge of the defeated Defender of Grammatical Sacred Cows: Credo quia absurdum!
Addendum. See UJG’s persuasive argument against the historically incorrect use of “they” as third-person plural pronoun. You heard me, plural.
Further addendum. Geoff Pullum provides further evidence of the triumph of singular they, which is used even in contexts (the wall of a men’s room, a discussion of pregnancy) where there is no need for gender ambiguity.