I am ready to confess: I do care a lot about the Oxford comma. The purpose of this post is to make you care too.
The Oxford comma, or “serial comma,” is meant to separate three or more items that appear in a series, with the comma appearing before the coordinating conjunction. For example, a certain advertising jingle should be punctuated this way: “I love baseball, hotdogs, apple pie, and Chevrolet.” Unfortunately back in 1975, when the commercial first appeared, the copywriters avoided the Oxford comma by using an ampersand (cheating). Perhaps no one in the television audience would even notice if the comma were missing. The problem lies in those examples when the absence of the Oxford comma causes confusion or ambiguity.
As I did with my posting on the m-dash, I can refer you to the Wikipedia article here for a less commercial illustration of the principle. For example, in a book dedication, a writer effuses “To my parents, Ayn Rand and God.” This writer’s dedication is confusing precisely because the Oxford comma is missing. Of course, it is possible that the writer is half divine, that Ayn Rand and God had a long term and committed relationship that produced at least one child. But my guess is that the writer’s parents are separate entities from Rand and God.
Punctuation is our wall of defense against the alien hordes of confusion and ambiguity. Vampire Weekend may disagree, but I say, we should care!