Bill will sort us all out.

Mick wrote:Consider this:

No one believes that chairs are immaterial. For if they did believe this, then they'd be insane.

I think that this sentence is grammatically correct and meaningful insofar as 'they' is singular and 'no one' refers to some set of believers. You could, I suppose, substitute 'they' with 'he' as well.

However, a fellow of mine with a phd in English disagrees. He thinks that the sentence is no good since ' no one' fails to refer but 'they' does refer.

Is this just a difference of interpretation regarding its reference or something different. Who is right if any one of us at all?

Ask him what methodology he has used to arrive at that conclusion, or whether he's just repeating claims made up by prescriptivists that may have been influenced by Latin grammar, some not too language-like formal logics, and their own personal preferences.

(Also, I'd be interested to know how he deals with - and for that matter, how everyone else here perceives - "there are no students here, they are elsewhere" or similar sentences.

In discussions like these, it seems people tend to fall into etymological fallacies and the like a lot. It can be a grammatical sentence even if "no one" originally didn't refer to anyone. Whether it's grammatical or not has to be decided by other means than discussing the meaning of the statement or whether it's unnecessarily prolix, etc.

don't get me started's answer was pretty good.

Why thank you Zwaarddijk.
Yes, I agree there is often a lot of unnecessarily abstract prescription in these kind of discussions. (I've been guilty of this myself on occasion.)
To tell the truth, a lot of 'grammar' in the traditional sense leaves me cold. I find it hard to get enthused by generative grammar and the likes, and I know from bitter experience that these kind of grammatical explanations often leave students none the wiser. ( Now, cognitive grammar...well, that gets me arguing with myself while I'm swimming..)
I've met quite few students over the years whose knowledge of formal English grammar is superior to my own.
When I teach this kind of stuff I always pay very little attention to form, some attention to meaning and focus heavily on concepts.
A lot of 'meaning' only emerges at the level of discourse and in this case I'd want to hear a prolonged stretch of discourse before I'd judge whether the speaker has done a good job in communicating his/her meaning. Is no-one in opposition to a certain somebody? Or, is no-one in opposition to a group of (stated or understood) somebodies? Or does the speaker not make the distinction on purpose?