My name is CatWoman, and I'm a self confessed spelling Nazi

[Emrys]

147. About the "Oxford comma" ...

I'll just dredge this up from my scintillating DU journal (I have a little time on my hands tonight if someone wants to get into an argument about it - no takers when it was originally posted).

I edit books. The Oxford comma is much misunderstood.

Nowadays, rather than having strict house styles, most book publishers are flexible about matters of style, like the Oxford comma, because they want to minimize costs resulting from changing what an author's submitted for publication. Generally, if what an author's done is consistent, or thereabouts, we'll standardize it throughout a chapter or whole book.

The Oxford comma means something different in book publishing than it does in everyday chatter.

It means the comma after the penultimate item in a list is obligatory in all cases.

It's nothing to do with making sense of a sentence by fiddling with the punctuation, that comma's just always there. The Oxford University Press explains why it adopted this practice:

Given that the final comma is sometimes necessary to prevent ambiguity, it is logical to impose it uniformly, so as to obviate the need to pause and gauge each enumeration on the likelihood of its being misunderstood – especially since that likelihood is often more obvious to the reader than the writer.

https://en-academic.com/dic.nsf/enwiki/256035

Translated from the somewhat flowery English: to save time spent by copy-editors deciding in every case whether there should be a comma after the penultimate item in a serial list, it's easier to just always use it, so that's what OUP imposes. And that's what a publisher means when they instruct us to standardize on using the Oxford comma or not.

This cuts out nuance, as in the examples people often give when arguing in the Oxford comma's favour, because that comma is not optional. But it saves time, and time is money.

So there you go: all those arguing for the Oxford comma have been doing it wrong all along. According to the Oxford University Press, anyway.