Ben Zimmer in the Wall Street Journal:
Copy editors might seem like stick-in-the-mud traditionalists when it comes to language change, but when I attended the American Copy Editors Society’s annual conference in Pittsburgh a couple of weeks ago, I found growing acceptance of a usage that has long been disparaged as downright ungrammatical: treating “they” as a singular pronoun.
According to standard grammar, “they” and its related forms can only agree with plural antecedents. But English sorely lacks a gender-neutral singular third-person pronoun, and “they” has for centuries been pressed into service for that purpose, much to the grammarians’ chagrin. Now, it seems, those who have held the line against singular “they” may be easing their stance.
“They” most often turns singular in common usage when its antecedent is considered generic, not referring to a single known person. Nearly everyone would find that they can stomach the “they” in this very sentence, agreeing with “nearly everyone.”
Things get trickier when the antecedent of “they” more clearly refers to one person. Areader of this column may not like what they see in this sentence, for instance.