I know it’s become common over these last few posts for me to discuss etymological fallacies, but that’s only because they’re so easy to disprove. They’re like a little vacation for me, a pathetic little vacation I take without moving from in front of my computer.
The current etymologically-motivated complaint I’ve grown tired of is the claim that you can’t say center around. This one’s fun because it involves geometry. (I must confess that I never actually took a geometry class. Instead, I took topology, which is sort of like geometry where the entire world is made of infinitely flexible rubber. This is why I can think of geometry as fun.)
Suppose you have a circle O. The circle gets its name from its center, O, so you might want to say that the circle O is centered at point O. But at the same time, the circle is located all around point O, so I can’t see anything unreasonable in saying that the circle is centered around point O either.
“How can you center around anything? You cannot. You can center on or focus on something, but not around it. Think about it!”
So I started to think about it. And try as I might, I couldn’t see how you could center on something. Take, for instance, that king of three-dimensional objects, the sphere. Suppose the sphere X is on point O. Then the sphere X must be above point O, by the definition of on. To have point O as its center, sphere X must extend equally in all directions from point O. (More generally, point O must be the average of all points in object X.) But it can only be the case that X is on O and X has O as its center if X is an impossibly droopy sphere; otherwise the center of X will have to be above O. Even if we move beyond spheres, it’s really only inverted bowl-type mathematical objects that could rest on their own centers. So really, isn’t center on illogical, too? Oughtn’t it to be center at?*
Please tell me you’re thinking that this discussion is really stupid. It is, isn’t it? After all, if geometric logic really determined the proper choice of preposition in an idiomatic construction, we’d all be saying that this debate centers at a contentious point. And of course, we don’t. The Google n-gram corpus has 4858 examples of “debate centers on” and 1763 of “debate centers around”, but does not have a single attestation of “debate centers at” in a trillion words. Language isn’t geometry, and there is no reason to try to make it so. As the Merriam-Webster Dictionary of English Usage (MWDEU) puts it, “[…] questionable or sound, logic is simply not the point. Center around is a standard idiom […]”
So let’s stop dismissing center around out-of-hand for “logical” reasons and look at it dispassionately. How standard of an idiom is it? Well, it’s a fairly old construction; the OED first attests it in 1868 in Edward Freeman‘s solidly scholarly The History of the Norman Conquest:
(1) “It is around the King..that the main storm of battle is made to centre.”
Google Books has some even older attestations:
(2a) “Clouds of deep crimson centered around him, and one would think, by the glory of his parting, he was loath to deprive the earth of her light […]” 
(2b) “[…] I occasionally acted as chaperon to Miss Jameson, but as my hopes centered more trustfully around one object, my taste for general society diminished […]” 
(2c) “His thoughts returned to Miss Percival; his hopes again centered around her.” 
Is center on any older? Not much. The OED’s first attestation of center on comes from 1789, but this usage is based on the obsolete definition “to converge on”. If we don’t accept that example because of the (subtle) difference in meaning, the next attestation is in 1867. That puts it contemporaneous with the first attestation of center around. Google Books has some older attestations, although they might fit better with the “converge on” meaning:
(3a) “Our hope centered on God in Christ, and our hearts ready to leave the world.” 
(3b) “Had it centered on a monarch, it would have given the means of a vigorous and healthy government; but it never centered on a monarch.” 
MWDEU notes that up through the 19th century, in was the primary idiomatic preposition used with center, alongside a smattering of on, upon, and around. More recent usage has shifted these proportions, with on and around taking precedence in American English and round frequent in British English. (in has really fallen by the wayside.) And between the emergence of center around and grammarians’ first complaints about it in the 1920s, no one seems to have thought it illogical. I guess they just weren’t as good at geometry back then.
Summary: There’s nothing illogical about center around, at least nothing inconsistent with the logic of language. (And center on isn’t a paragon of logic itself.) Regardless of the question of logic, center around has been around for 150 years, and there’s no reason to ditch it now.
*: And while we’re at it, why are prescriptivists willing to accept center as a verb in the first place? Don’t they know the verb center comes from the noun center? I thought they hated all the bastard verbs that come from nouns, like access.