Try this. Neither Jack nor Jill have come down the hill. None of their cousins have seen them. Are those two haves correct? Shouldn’t they both read has?
You don’t know? You’re not alone. There’s a thicket of alleged rules for the use of neither... nor, no one (in the sense of “nobody”) and none. Not all are genuine.
Start with the easiest: no one (best spelt that way, without a hyphen, though some people insert one). It always takes a verb in the singular: as in and no one disputes this. End of story.
But what about none? As a child, I was taught that this is just a shortening of no one (which historically it wasn’t), so it must always have a singular verb. Untrue.
Far from it, if the entities you’re on about are plural ones, none flatly demands a plural verb: the Americans, the Russians, the Chinese — none of them were present. You don’t mean that not a single American, Russian or Chinese turned up at the event (a UN conference on global non-aggression, maybe?) but that these nations were absent, as nations.
Much more widely, there’s often a choice. I’d write none of us is immortal, because I do specifically mean that not a single human being will live for ever. But I’d probably write none of my friends are rich more often than is rich. That’s merely my preference, but at times the surrounding words give active guidance. You can’t say none of the money have been embezzled, but you might well choose none of the pupils have turned in their work rather than has turned in his or her (or their) work.
And now neither... nor. Let’s prune away one so-called rule at once. Pedants say there must be only two ‘subjects’ involved — as in neither Jack nor Jill —never more, as in neither Jack nor Jill nor Uncle Bill. That is true if you’re using neither as a pronoun: you can’t say of ghosts, gnomes and goblins, neither frightens me. But in the common use of neither it is rubbish.
It sprang from the silly idea that if something held good in Latin (whose neuter, looking much like neither, meant “neither of two”) it must apply in English. As with the notion that you can have no more than two alternatives, because Latin’s alter meant “other of two”. Tosh. You can have two or four or 24.
What about the verb? Singular or plural? It used to be argued that, with two (singular) subjects, the verb must be singular: neither Jack nor Jill has come down, not have. I like this usage (even if Uncle Bill is involved as well), but “must” is too strong. There are historical precedents for a plural verb, and you can meet that today, even in print, and quite often in ordinary speech.
Humph. R.W. Burchfield, editor — in reality, rewriter —of the third edition of Fowler’s Modern English Usage commented that “what was acceptable in the 18th and 19th centuries may [be] questionable in the 20th.” I agree. I find neither Putin nor Obama are perfect as pointlessly odd in grammar as it is true in sense.
Of course, if the two subjects are both plural, then the verb must be too. But if one is plural, the other singular? I’d go for the plural, even if the singular noun is the one near the verb: neither lies nor bluff were any comfort to the bereaved. And what if the subjects demand different forms of the verb: neither he nor I is/am a genius? The best advice is to find a way round: he’s no genius, nor am I.
Or, as I could have written, “neither” am I. Which — let me cut back the thicket still more — you can rhyme with nigh or with knee, exactly as you choose.