A fun fact I learned just recently is that even Shakespeare used singular "they":

http://itre.cis.upenn.edu/~myl/languagelog/archives/002748.h...

(and even singular "themselves"!)

which puts to rest approximately every argument I've ever seen against it.

Because this often ends up with people talking past each other, never until a few years ago did anyone use singular they for a known, specific person. Shakespeare used it for unknown or nonspecific people.

It was also used in the King James Bible, published in 1611.

Interesting. Shakespeare had first used singular 'they' in 1594, so not even that long before.

In casual use, yes. In formal writing, the broad switch to acceptance of singular "they" is only about 15 years old. Up until that point it's the sort of thing that would be flagged by an editor, or lose you marks in an English paper.

I'd be shocked if that were universal over that time, given that even formal language has undergone many changes in attitude. Over hundreds of years, I bet that in many times and places it has not considered it a problem, particularly given its use in the King James Bible.

And Oceania has always been at war with Eurasia.

It's been qualified as “bad grammar” by many people over the years though.