You know it, and you love it or hate it—it’s the last comma in a simple series, the one before “and,” “but,” or “or.” (Or, the one before “and,” but” or “or.”) It even has aliases: the Harvard comma, or the Oxford comma. As mentioned here on numerous occasions, many people are more passionate about the “serial comma” than about politics or religion.
It’s misplaced passion.
Simply put, whether to use that final comma is a matter of style—not one of grammar, education or national honor. It’s a choice, not a mandate, the way the need to match the tenses of subjects and verbs is a mandate.
CJR, for example, uses it. Most news publications do not, but many magazines do, even news magazines. So CJR has simply decided to identify itself more closely with magazines than with news publications, at least stylistically. A publication is not more or less accurate or credible because it decides to use—or forgo—that little curlicue.
Now that you’re good and mad, let’s look at this a little more closely.
People who argue that the “serial comma” is necessary for clarity usually use examples like this one: “My favorite sandwiches are pastrami, peanut butter and jelly and cream cheese.” Because the verb is plural, it’s clear that there are at least two favorite sandwiches. But because there are two “ands,” it’s unclear whether the favorites include “pastrami, peanut butter(,) and jelly,” “peanut butter and jelly,” “jelly and cream cheese,” or “peanut butter and jelly and cream cheese.” Any series that allows that kind of confusion is, by definition, not a simple one.
Instead, the recommendation to omit the “serial comma” is intended only when no ambiguity would result from it. Here’s how The Associated Press Stylebook puts it:
Use commas to separate elements in a series, but do not put a comma before the conjunction in a simple series: The flag is red, white and blue. He would nominate Tom, Dick or Harry. Put a comma before the concluding conjunction in a series, however, if an integral element of the series requires a conjunction: I had orange juice, toast, and ham and eggs for breakfast. Use a comma also before the concluding conjunction in a complex series of phrases: The main points to consider are whether the athletes are skillful enough to compete, whether they have the stamina to endure the training, and whether they have the proper mental attitude.
Complaints about the lack of the final comma often arise when a sentence that needs it doesn’t have it, as in the sandwich example above. But many readers also complain that it’s missing from a simple series, too, though they can rarely give any reason to use it beyond grammar rules or hobgoblinish consistency.
Usage authorities have been split for years, with a majority favoring the “serial comma.” (Fowler was agnostic but leaning toward omitting it; Strunk and White favored it.) But if no ambiguity would result, why mandate it? Especially if there’s no universal agreement about the “rules.”
In the case of the “serial comma,” common sense—and house style, if it exists—should trump the “rules.” In a simple series, when no one would be confused by the lack of a final comma, use the “serial comma”—or not—as your style manual prefers, or as you prefer if there is no style manual. But if there’s any chance of ambiguity, use it.
Now, about peace in the Middle East …