Quote by Henry Spencer, U of T, from a thread on this very topic:
Quote:The New Fowler's Modern English Usage, while vaguely disapproving of the
practice (and noting that Fowler objected to it), observes that the OED
makes a good case that it has been common practice for centuries, notes
that it can be found in places in New Fowler's itself, and surrenders,
concluding: "The process now seems irreversible.".
(Not everyone approves of the New Fowler's. It is mostly rewritten from
the original, and is only one man's opinion. But then, so was the
original. And while Fowler often gave good advice, he was notorious for
being far more influenced by late-Victorian grammar textbooks -- which
*were* often seriously revisionist -- than by the actual history of the
English language.)
I also note that it's not a particularly obscure usage. You don't need
to resort to the OED; my desk dictionary (Webster's New Collegiate 1975)
lists it, and does not flag it as colloquial.
Also, in case my last post wasn't clear, "you" was originally a plural pronoun, and was expanded to singular use, overtaking the whole "thee" "thou" "thy" paradigm. So singular "they" to us now should be no more offensive to our ears than singular "you" a couple hundred years ago!
The "new" plurals "youse", etc. are an attempt to disambiguate the paradigm once again.