“I never use it.”
“I always use it!”
“I only use it when necessary.”
“It’s always necessary!”
“It impedes the flow of reading.”
“I mark my students’ papers incorrect if they don’t use it!”
Many of us learned in school that the final comma in a series was not necessary. Still others learned they are absolutely required no matter what. So what is the final, definitive rule for punctuating the elements in a series with the Oxford comma?
According to Oxford Dictionaries, the Oxford comma (also known as the serial comma) is an “optional” comma separating the last item in a list or series immediately prior to the conjunction (most commonly “and”):
We sell cheese, crackers, and relish.
The flag is red, white, and blue.
My favorite pies are apple, cherry, and chocolate cream.
In the examples above, there really wouldn’t be any confusion if there were no serial comma. They are all simple, straightforward lists, and the meaning would still be clear without it.
To Oxford or not to Oxford?
With all the debate over the Oxford, I decided to do a little research and performed a very unscientific survey of fellow grammar nerds, er, I mean teachers, and the response was overwhelmingly in favor of its use. About half the respondents indicated that they mark it as incorrect if it is omitted, and several said they mark it incorrect because the SAT exam counts its absence as incorrect.
According to Lynn Gaertner-Johnston’s Business Writing website, she surveyed 11 current style guides and found
7 recommend including the comma before the conjunction.
2 (Merriam-Webster’s Collegiate Dictionary and Canadian Oxford Dictionary) recommend the comma before the conjunction but acknowledge that some writers omit it.
2 (The AP Stylebook and The Canadian Press Stylebook) leave out the comma before the conjunction unless doing so would cause confusion.
The AP Stylebook noted in the final example above, is used by journalists, newspapers, and many magazines who omit it to save space and improve flow.
The name, Oxford comma, comes from Oxford University Press, where editors and printers required its use. However, not all publishers use it, or use it only when the meaning could be confused without it. For instance, in the example from The Chicago Manual of Style Online,
With gratitude to my parents, Mother Teresa and the pope.
there is no comma before the final item in this series “the pope,” so this seems to be saying that the writer is thanking his parents, who are Mother Teresa and the pope!
However, with a serial comma, the meaning changes:
With gratitude to my parents, Mother Teresa, and the pope.
Now it’s clear that this writer thanks his or her parents, and two other people: Mother Teresa and the pope. This makes more sense!
In the following list of menu side items, you might be confused as to what exactly you are eating, depending on the final comma:
Available side dishes include potato, fries, rice, peas and carrots.
How many items do you have to choose from? Four – or five? Are the peas and carrots one combined side dish, or two separate veggie sides?
If the Oxford comma is used,
Available side dishes include potato, fries, rice, peas, and carrots.
you have five sides to choose from, as the comma communicates that the peas are one item and the carrots are a separate item.
When Additional Words are Needed
Without a serial comma in the following example, the sentence communicates that officer and gentleman are describing John:
I went to see John, an officer and a gentleman.
There is no comma prior to “and,” which indicates that “an officer and a gentleman” describes John. Consider if there were a serial comma:
I went to see John, an officer, and a gentleman.
This could mean that you saw 3 people, one being John, the second, an officer, and the final, a gentleman. However, it could also mean you saw John, who is an officer, and another separate man who is a gentleman. Confusing! To clarify this example, you may need to add more words of description to guide the reader and avoid confusion:
I went to see John, who is an officer and who is also a fine gentleman.
I went to see John, who is an officer, and another man who was a fine gentleman.
The most important thing to remember is that regardless if you are a proponent of the Oxford comma or not, writers should always err on the side of what usage communicates most clearly, and in most cases, using the Oxford wins the debate.