I have often heard presenters talking about something centered around another thing, but it seems a bit illogical and hence improper to talk like this. Am I right about this?
Quoting the Wiktionary usage notes for center:
Merriam-Webster's Collegiate Dictionary observes that center around is objected to by some people on the grounds that it is illogical, but states that it is an idiom, and thus that such objections are irrelevant. It offers revolve around as an alternative to center around for those who would avoid the idiom.
Here is Merriam-Webster's original wording:
Usage Discussion of center
The intransitive verb center is most commonly used with the prepositions in, on, at, and around. At appears to be favored in mathematical contexts; the others are found in a broad range of contexts. Center around, a standard idiom, has often been objected to as illogical. The logic on which the objections are based is irrelevant, since center around is an idiom and idioms have their own logic. Center on is currently more common in edited prose, and revolve around and similar verbs are available if you want to avoid center around.
The phrase "X is centered around Y" makes sense if you consider Y to be a smaller, central object and X to be a set of related, but distinct, objects whose collective center coincides with Y. In other words, individual members of the set X are not centered on Y, but the collection of all members of X are.
"The planets of our solar system are centered around the sun."
"My arguments are centered around the hypothesis that every dog has his day."
To centre X is to place X in the middle. However in Y is centred around Z, the first part Y is centred suggests that Y is in the middle while the second part around Z suggests that Z is in the middle. This explains the feeling of the absence of logic. Nonetheless,
The news centred around him
is correctly used to mean that he is in the centre of attention, not the news.
When you focus on an object, you make it the center of your attention—and in my experience, few writers are tempted to describe this action as "focusing around" the object. But in the case of "centering" rather than "focusing," many writers and speakers opt for "centering around" in preference to "centering on," even though a similar kind of specific attention is involved.
One obvious instance of focusing is a camera focused on a focal point; and one obvious instance of centering is a circle centered on its midpoint. In neither case, I think, does "around" describe the relationship of the action of the subject (camera or circle) with respect to its object (focal point or midpoint) as well as "on" does. In the case of a circle, the "around" action works far better with "orbiting," "revolving," or "circling"—though in that case what physically moves around the midpoint is a point on the circle (not the circle itself), as a satellite with a perfectly circular orbit would move around a star or planet.
Interestingly, although (as noted in RegDwigнt's answer) a usage note in Merriam-Webster's Eleventh Collegiate Dictionary (2003) argues that logic is irrelevant to the validity of an idiom (and therefore that "centers around" is perfectly valid), that dictionary employs "on," not "around," in the two examples that it includes to illustrate its definitions of the verb center:
center vt (1610) 1 : to place or fix at or around a center or central area or position [center the picture on the wall] 2 : to gather to a center : CONCENTRATE [centers her hopes on her son]
In the first example, the dictionary couldn't very well have said "center the picture around the wall" without suggesting that the picture somehow enveloped the wall; but in the second example, the dictionary could have used "around" in place of "on" and justified doing so by citing idiomatic usage. Nevertheless, it didn't. Merriam-Webster's favoring of "on" in its examples reflects the wider preference (as of 2000) in overall print usage, which, according to Google Books' Ngram Viewer, favors "centers on" over "centers around" by a margin of greater than 2 to 1:
I find two things especially interesting about this Ngram chart. First, it indicates that neither "centers on" nor "centers around" was at all common before about 1880. ("Focuses on" likewise appears to be something of a latecomer to everyday written English.) Second, the chart shows that "centers around" and "centers on" were equally popular in published works from about 1880 until about 1914, and that "centers around" was slightly more popular than "centers on" between 1915 and 1950. Only after 1955 did "centers on" emerge as the preferred form.
A similar pattern is evident in the Ngram chart for "centered on" (blue line) versus "centered around" (red line), except that "centered around" was never quite as frequent as "centered on":
Again, the trajectories for the two curves change around 1950.
The chart for "centering on" (blue line) versus "centering around" differs from the previous two charts in showing a clear preference for "centering around" from about 1910 until the early 1960s, followed by a fairly steep decline in (instead of a leveling off of) the frequency of that term, along with a sharp rise in the frequency of "centering on" from about 1910 until the middle 1970s:
I think that the rather late changes in favor of "centers on," "centered on," and "centering on" in these three charts are more plausibly explained as showing the effect of a style preference imposed on published writings from outside (that is, by editors and teachers wielding usage guides) than as reflecting an organic reversal of preference among English speakers who were suddenly struck en masse by the persuasiveness of the logical argument in favor of "centers on."
I agree with oosterwal. Centered can be defined simply as "in the center", and would be the meaning of the word in the publishing sense, as in centered justification (as opposed to right or left). In that case, if you place something in the middle of whatever is centered in the larger context (like a page), such as an O between two Xs... XOX, the Xs could certainly be said to be centered around the O; in the middle, not skewed to one side or the other. The sun in the solar system is a good example.
Unfortunately, Microsoft Word puts a big green grammar underline under my use of the the phrase, so I always change it to "centered on" to be a conformist. :P