This isn’t unique to the coordinator nor; it happens any time we begin a clause with a negation or negative-like word or phrase; for example, Never does he check his answers, or Rarely does he check his answers, or Only when reminded does he check his answers.
However, other than the requirement of a negative first clause, and flip-flopping the subject and auxiliary verb in the second clause, can we sum up by saying that nor is like for and so, because the only things it can join are clauses? Well, not quite.
Or Versus Nor
For many speakers and writers, nor can also join other kinds of phrases if they’re inside a negated phrase. For example, take the idiom I haven’t seen hide nor hair of him. It means I haven’t had even a glimpse of someone. Now for me, this phrasing is a bit odd; I would want to say I haven’t seen hide or hair of him. Similarly, for many speakers, a sentence like Aunt Margaret was never hateful nor mean is completely normal, but for me, it would have to be Aunt Margaret was never hateful or mean.
Using or instead of nor in these situations reminds me of a rule from classical logic and computer science called DeMorgan’s Law. If you’ve studied logic or computer science, you’ll know immediately what I mean, but you haven’t, that’s OK. The main point is that the phrasing never hateful or mean mirrors classical logic more closely than never hateful nor mean. But as you probably know if you’re listening to this podcast, no natural language is completely logical, not English nor any other. So what do the usage guides have to say about nor instead of or to join items inside a negated phrase?
Archaic Language Calls for Nor
The Merriam-Webster Dictionary of English Usage cites two usage guides published more than 100 years apart, each giving different advice. The older one, published in 1881, calls for nor, while the newer one, published in 1982, calls for or. Their conclusion is that or must have sometimes been used like this in the late 1800s—or else why would a usage guide have had anything to say about it?—and “that it has become prevalent in the century since” (661). Garner’s Modern American Usage says that or is usually the better choice, though he doesn’t call nor nonstandard.
He Speaks Not Versus He Does Not Speak
The most interesting advice I found was in Fowler’s Modern English Usage, originally published in 1926. Fowler makes an interesting distinction. He talks about a period of English when the present-day system of negating verbs hadn’t completely settled, so that instead of saying that someone “doesn’t speak,” you could also say that they “speak not.”