For generations, probably for centuries, Anglophone writers have struggled with the fact that our language lacks a gender-indeterminate third-person singular pronoun. In English, we have he for a man, she for a woman, and it for everything else. There is no option in the third-person for someone whose sex is unspecified. There are of course ways to get around the problem. Consider the sentence “A candidate for federal office must disclose his campaign spending.” The writer may opt for his or her instead of his (though that can be cumbersome if done more than once in a short space), her in one instance and his in another (though that can confuse), or simply shift to the plural: “Candidates for federal office must disclose their campaign spending.”
The lazy and ill-advised way to solve the problem—just pardonable in spoken English, less so in written English—is to use they and them when it’s convenient: “A candidate for federal office must disclose their campaign spending at the end of each quarter.” Their is plural, even though it’s only one candidate.
Now, however, the dictionary of the young—namely Dictionary.com—has given its blessing to the lazy usage. “They,” an unsigned piece posted last week on the site tells us, “is not only a plural pronoun.” How do we know this is true? Because an anonymous writer at Dictionary.com says it is. The evidence mounted for this judgment, though, isn’t the usual claim that the misuse is so common as to make it correct, though the writer—whoever he is—does allude to the populist justification: “This chameleon word is also a singular pronoun, and it has been for centuries. Etymologists estimate that as far back as the 1300s, they has been used as a gender neutral pronoun, a word that was substituted in place of either he (a masculine singular pronoun) or she (a feminine singular pronoun).”
The real reason for the judgment is, as you might guess, that the author subscribes to the fashionable view that sex is nonbinary. Using the singular they is “a good way for people who don’t identify with the binary genders of female and male to describe themselves because they and them are not gendered.” Really? We would have thought referring to yourself as they and them would suggest a personality disorder. But the e-lexicographer is serious: “Sharing our pronouns is a way of sharing our gender identity with the world. You might identify as female and ask that people refer to you as she / her. Or, maybe you identify as male and your friends use he / him when they talk about you. For other folks, they / them are the appropriate pronouns to use.”
Well, okay. But for writers who wish not to be thought of as maleducated—and for those who don’t believe human beings are reducible to grammatical units—we supply H. W. Fowler’s advice, first published in 1926. Fowler conceded that excellent writers have occasionally transgressed the rule (he quotes William Thackeray observing “A person can’t help their birth”) but insists that “few good modern writers would flout the grammarians so conspicuously.” Emphasis on good.