An oldie to get started: the serial comma
I’ve noticed, over the last few years, that supposedly well-edited books—bestselling nonfiction and fiction from large, old-line trade houses, often in a second or third or later printing, after which there is no excuse for residual errors—have quite a lot of internal inconsistency in comma use in general (not just the use of the Oxford comma*), something I find annoying and mildly distracting as a reader.
What seems to be happening is that modern writers and editors have backed completely away from the notion that comma use should follow a consistent set of formal rules. Instead, they’ve gone back to the earliest historic use of the comma’s precursor, the breath mark, and now use the comma only or at least primarily to indicate rhythm. I honestly don’t know whether this trend is the leading edge of a self-conscious nouvelle vague or if it is just testament to dumbing down of American education through the triumph of Whole Language over traditional teaching methods.
Of course the above observation does not apply to all books. Some writers write for the eye; others write for the ear. In the former group, you’re likely to find fairly consistent, rules-based commas usage. It’s the latter group where authors get uppity with editors about putting commas in odd places so that the prose “sounds right.”
In any case, for technical writing and, indeed, any business writing that falls outside the marketing communications (marcom) umbrella, as well as for most other kinds of nonfiction, keeping the Oxford comma is the safest choice. For marcom, it’s usually better to drop it, whether you are following AP style for a news release or writing a print ad. However, this requires great care in crafting sentences to avoid any potential ambiguity.
When I’m editing fiction, I don’t use the Oxford comma.
* The Oxford comma, sometimes called the Harvard comma or serial comma, is the comma that separates the penultimate item in a series from the following conjunction. The usual argument for it is that it eliminates ambiguity. The usual argument against it is that it is redundant. If you see the comma as a mark indicating that a conjunction has been omitted (red and white and blue) then it looks redundant. If you see it as a pause or as a formal separator, it does not look redundant.