One of those usage guidelines that refuse(s) to be pinned down . . .

The Common Errors in English Usage entry for May 9 was this:

one of the (singular)
In phrases like “pistachio is one of the few flavors that appeals to me,” I think you should use the singular form for the verb “appeals” because its subject is “one,” not “flavors.” However, note that usage experts are all over the place on this subject and you’re not likely to get into much trouble by using the plural, and some authorities absolutely prefer it.

 . . . which elicited a well-founded rebuttal from a commenter explaining the reasoning of usage experts alluded to in the entry itself:

Tom, I have to disagree. Here the subject "flavors," though a genitive in the main clause, governs the verb "to appeal" in the relative clause as subject. The singular formulation is rare in literature before the later twentieth century, for example, and for good reason. It's also nonstandard in other Indo-European languages, to the best of my knowledge. This is essentially a mass malapropism caused by attraction between the end of the main clause and the verb in the relative clause. It's now dominant, but it's just as wrong as "between you and I" (also arguably dominant and endlessly parroted).

I put up a clarification reply, pointing out—as I'm wont to do—that I am not the author of the entries but rather the editor of the book based on the Web site that supplies the entries for this blog, but that I agreed that the original advice was solid: Using the singular verb "appeals" should not cause any problems with a sophisticated audience of native speakers of English. I don't mean to insult anyone who thinks otherwise, but modern popular usage in edited sources does back me up on that. The commenter asserts that using the singular verb in this sort of construction is "dominant." I don't have enough access to a reliable corpus to know whether this is true, but it is certainly not uncommon.

I think it is worth adding that the commenter is correct, and the entry should clarify that the formal subject of "appeals" in the example sentence is not "one"; it is "that," and "that" as a relative pronoun refers to "flavors" rather than "one."

Nevertheless, there is a history of writers treating "One of those [ _____s ] who/that" sentences as singular. Obviously, this creates problems for critics who would have sophisticated language usage governed strictly by formal grammar, but there is a rhetorical term for this notion that goes back to the Greeks, "synesis," which describes the phenomenon of determining gender or number agreement based on the general sense of a sentence, and not strictly in terms of formal grammar. I agree with Webster's Dictionary of English Usage that here we have an example of synesis, or as they call it, "notional agreement" at play. Webster's goes further, pointing out that Joseph Addison and others have not strictly adhered to using one form or the other. This need not be incongruous if you stick to an overarching principle of choosing the verb form that best represents the sense you are trying to communicate. In the case of the "pistachios" example sentence, selecting "appeals" over "appeal" reinforces the singularity of one person's opinion being expressed and the small number of flavors that appeal to that person.

Having said all that, and having thought this over a bit more, I will continue to refrain from batting an eye when I see this sort of construction in print or pricking up my ears when I hear it used on NPR or anywhere else. Nevertheless, there is one case where I am certain I would choose the plural verb every time: When taking a standardized test on grammar. Those devices are notorious for enforcing formal grammar over practical usage.