Languagehat takes another swipe at the piñata of bloviation that is Bill Safire's "On Language" column. While the 'hat's concern is with the nonsensical phrase "common elitist usage", this ex-engineer wishes to pick at another comment of Safire's, "That explains the rise of unipolar, a pole with only one end, as impossible in logic as multipolar." (italics in original)
Safire starts off sensibly enough, noting that:
A pole, from the Greek polos, ''axis,'' is ''one of two ends of an axis going through a sphere.''
So we're working from the notion that poles come in pairs, and represent dichotomies when used metaphorically. SC can follow him this far. Your host can even follow him as far as his complaint that the word is abused by politicians because of an analogy with "lateral", where "bilateral" is a neutral term, "unilateral" is bad, and "multilateral" is good; hence, "bipolar" is neutral, "unipolar" bad, and "multipolar" good.
But since Safire's the one complaining that these usages "departed from the word's metaphoric base" (italics mine), and that he doesn't want to be bound by "strict etymologists", then he has to be called to the carpet for claiming that "multipolar" is a logical impossibility. If "bipolar" is supposed to be a metaphor for two-valued logic, and so poles = logical values, then there's nothing wrong with calling the work of this guy "multipolar logic". Judging by Google's results (just 14 hits for that phrase, all irrelevant), nobody actually does, but perhaps only because the term "many-valued logic" was coined before "multipolar" came into fashionable use.
There's another usage of multipolar that Safire's reasoning requires him to consider an abuse, though, and this one is a lot more common, at least among the people who keep your local power grid running. The relevant definition can be found here, and refers to the number of magnetic poles in a motor. There are 4-pole motors, 12-pole motors, 24-pole motors...so much for poles being binary opposites. Admittedly, in this usage, the poles always come in pairs, but the poles are generated by currents which aren't in phase with each other, so any two positive poles aren't identical.
Another use of poles/polar from engineering where the number of poles isn't limited to two comes from the notion of "transfer functions". Briefly, a transfer function describes the output of a system for a given input, and is written as the ratio of two equations whose meanings aren't terribly relevant here. The solutions to the equations have special properties, though, and are known as "zeros" (where the transfer function's magnitude is zero) and "poles" (where the magnitude is infinite). A transfer function can theoretically have an infinite number of poles, and if you're really dying to know more, go here.
SC wouldn't normally pick at this, since Safire is basically correct about the use of "polar" being derived from the Greek for "axis", and that its original intent was to represent opposites. However, it's not fair to both object that insistence on "strict etymology" is wrong and should be trumped by real usage, and then also complain that some usages don't rigorously follow the original etymology. Again in fairness to Safire, this isn't something the people at Merriam-Webster have picked up on, either: the only definition they give hinting at the possibilities of poles not just being binary opposites is part 3b of entry #3: "one of two or more regions in a magnetized body at which the magnetic flux density is concentrated" (note: SC only checks the free version, not the pay-for-service unabridged one). But linguistic creativity is about taking old, familiar words and constructions, and expanding them to handle new meanings. Clearly, "pole" has been reanalyzed to refer to a single extremity, or one half of a non-unique pair, and is used as such in the engineering lingo. One might expect that he'd check this out before...ahem...unilaterally declaring the logical impossibility of more than two poles.