Like any diligent linguistics nut, I read Dinosaur Comics and xkcd. Naturally, I therefore spend no small amount of time thinking about pronouns. Specifically, ones like "he" and "she," but more importantly, "he or she." I support the view T-Rex advances in this strip (which is actually an xkcd parody of Dinosaur Comics): "they" as a third-person singular gender-free pronoun. Dromiceiomimus' point that it is "bad grammar" is, as T-Rex suggests, just a social construction. Indeed, not only has "they" been used for a long time, grammar changes over time. We already got rid of "thee" and "thou" because English-speaking society no longer had use for two sets of politeness terms; now that we actually need a 3PSGFP (as I will call it), we don't have one, so we can either create something ridiculous like "xe" that has no pronunciation, or we can simply shuffle around our existing set of pronouns to take on new functions.
Of course, using existing pronouns creates comprehension difficulties. For instance, consider the sentence "Someone killed their family." According to "proper grammar," this can only mean that someone killed X's family, where X is some set of people that doesn't include the subject. But if we allow "their" to be used as a 3PSGFP, then X may also include the subject. Without context, we don't know the intended meaning.
This seems like an argument against my suggestion. However, what's so bad about context dependency? Anyone who has studied Japanese knows that almost nothing can be interpreted without a context. "Someone killed their family," in context, becomes immediately clear. If you just walk up to a chick at a bar and say "Someone killed their family," she'll probably just frown and look away. But that's not because she's not attracted to you; she just doesn't have a context in which to interpret your utterance, and this unsettles her. Uneasy and confused, she must turn away to hide her embarrassment.
But if you say "Hey, I read in the news, someone killed their family," your utterance will imply that "their" refers to the subject. But if you say "Hey, did you hear about the Johnson boys? Someone killed their family," clearly "their" refers to the Johnson boys. Language without context is just philosophy, and no one wants that.
The only other argument against my position that I can think of is that proper grammar is a way to tell the educated from the uneducated. When Professor Universityprofessor hears you say "I done ain't not seen thurn herm jerb tootin'," he knows you did not attend Yale. However, in today's society, this issue becomes less and less significant, and also, who cares what Professor Universityprofessor thinks about your education? Besides, he has such a silly name.
So if using "they" as a 3PSGFP increases the efficiency and communicability of language, that should be reason enough to accept it as a change. Even if it is used unconsciously, as it so often is nowadays, if that is the direction in which language is heading, antiquated conventions are of no use. After all, if language wasn't supposed to change, it wouldn't be called "language." Duh.
