“Singular they” was the American Dialect Society’s pick for word of the year for 2015. I’ve been a big proponent of singular they ever since I realized it was a systematic thing I do.
“Singular” they is not really grammatically singular, but it’s used to refer to a semantically singular person. Most people use this in conversation and don’t even notice. It’s used in sentences like
“When I teach someone grammar, they look even more confused.”
“A journalist should not be forced to reveal their sources”.
Here, “they” is referring to the grammatically and semantically singular nouns “someone” and “a journalist”. You can tell that “they” is still grammatically plural because “…they looks even more confused” is clearly ungrammatical. But the meaning is clear: “they” in “they look even more confused” is referring to the single “someone” I was trying to teach.
The reason this is important is because our singular pronouns in English are gendered. There’s not a gender inclusive singular pronoun. Historically, people used “he” in a gender-inclusive way, so our sentence would turn out like:
“When I teach someone grammar, he looks even more confused.”
This is grammatically and semantically singular, but sounds a little weird to modern English speakers: why am I pointing out his gender?? Is that relevant? Am I saying that I’m not as good at explaining things to males? Am I talking about a particular “he”?
These thoughts are probably not conscious, but there is a trend in our language today towards gender inclusivity. People have tried to come up with a gender neutral/inclusive singular pronoun. In text, “s/he” works fairly well, but when you are speaking, there is not a good singular option. There have been pushes to try to get a new pronoun adopted, like “zhe”, “hir”, or “co”. But those are doomed to failure in natural language because pronouns are what is called in linguistics a closed class. There’s not room for things to be added, especially not from an organization trying to get people to use them. Languages don’t add pronouns just because it’s politically correct to do so. But languages can repurpose the pronouns they already use to fit the semantic meaning they are trying to communicate.
And that’s where “singular” they comes in. No, it’s not grammatically singular. But it is filling a lexical gap in the English pronoun inventory. As we as a society try to be more inclusive, we need to change how we use language. But we don’t always need to invent new words to get the job done. Re-purposing “they” will work just fine for now.