I knew James Kilpatrick was nutty on the subject of only, but it was only when Neal Whitman blogged about it that I learned the depth of his obsession. Kilpatrick has devoted an annual language column to this largely bogus writing tip for 20 years.
In this year's outing he says, "The trick is to snuggle the limiting 'only' as closely as possible to the noun it modifies. It works every time."
Even after 20 tries, though, Kilpatrick hasn't quite gotten a grip on the fine points of his subject, as Whitman demonstrates:
[W]hen he says to put only as close as possible to the noun it modifies, I’m sure he meant word, since Kilpatrick certainly knows that hit is a verb, and in a preposition. The trouble is that Kilpatrick’s rule doesn’t work every time. …He is assuming, and leading his readers to believe, that the only things that only can modify are words. In fact, it can modify whole phrases.
One of Kilpatrick's sample sentences is "John hit Peter only in the nose." Not good enough, says Whitman: "If he wants only to narrow down just what parts of Peter’s body John hit, he should follow his own advice and put only as close as possible to the noun it modifies, and write John hit Peter in only the nose." It's either that or admit that only can modify phrases, and that moving only around can't eliminate every last theoretical ambiguity.
Some years ago, I decided that usagists must be stuck on only because they love ringing the changes on those sample sentences: I only have eyes for you, etc. And more than once, I've asked readers to send me an example of an only, in edited prose, whose placement produces genuine ambiguity. That challenge went out in 2001, and I'm still waiting.