There's not a subject more divisive to grammarians, writers, and editors than the usage of the Oxford (or serial) comma. The Oxford comma is the last comma used in a list of three or more items and is stylistic in its usage, which essentially means that you use it depending on what kind of writing you're doing. Proponents of the Oxford comma say that this last comma provides clarity and helps the reader. However, those anti-Oxford comma writers out there say that this last comma clutters up the page and that the use of it may even contribute to more confusion.
So, how do you know if you should use it in your writing? Why should you use it (or why should you not)? Here is a guide to all things Oxford comma to help you determine which side of the argument you fall on.
What is the Oxford comma?
The Oxford Dictionary's website defines the Oxford comma as, an optional comma before the word 'and' at the end of a list… it's known as the Oxford comma because it was traditionally used by printers, readers, and editors at Oxford University Press. Not all writers and publishers use it, but it can clarify the meaning of a sentence when the items in a list are not single words.
The history of the Oxford comma is a bit murky, but according to an article on Business Insider, the first person to write down this powerful little punctuation mark as rule was a man named Frederick Howard Collins who was a British indexer and writer. He featured commentary on the serial comma in his 1912 book published by Oxford University Press entitled, "Author's & Printer's Dictionary: A Guide for Authors."
In his reasoning for using the serial comma, Collins wrote:
The late Herbert Spencer [the Victorian philosopher and scientist] allowed me to quote from his letter:—"whether to write "black, white, and green," with the comma after white, or to leave out the comma and write "black, white and green"—I very positively decide in favour of the first. To me the comma is of value as marking out the component elements of a thought, and where any set of components of a thought are of equal value, they should be punctuated in printing and in speech equally. Evidently therefore in this case, inasmuch as when enumerating these colours black, white, and green, the white is just as much to be emphasized as the other two, it needs the pause after it just as much as the black does.
So essentially what Collins was saying (through Spencer) is that just because something is last in a list doesn't mean that it shouldn't get the same pause and treatment as the first two or more items in a list. For the last century, Oxford University Press and other institutions of style and grammar have insisted on the usage of this last comma.
When should you use the Oxford comma?
Now that we know a little bit about the history of the Oxford comma and that it's used to clarify sentences with two or more items in a list, how do we know when to use it in our writing? Because it is stylistic in its usage—meaning that it's just the preferred style of the way a sentence looks and not a "rule" per se—you aren't always going to be using the serial comma.
Here is a list of some of the most common style guides you will be using while writing, and whether or not they use the Oxford comma:
- Associated Press Style (AP) does not use the Oxford comma.
- American Psychological Association Style (APA) does use the Oxford comma.
- Chicago Manual of Style (CMS) does use the Oxford comma.
- The Modern Languages Association (MLA) does use the Oxford comma.
- The Oxford University Press (OUP) does use the Oxford comma.
You may have noticed that the only common style guide we have listed here that does not use the Oxford comma is the Associated Press (or AP) style guide. This guide is the stylebook for journalists, public relations, and advertising professionals. There are several reasons why AP does not use the Oxford comma, but it's mostly not used as a way to use space efficiently within their paragraphs.
So now that we know when we are supposed to use it, let's look at some examples to show us how it's done. Here are some sentences that could be clarified using the Oxford comma:
Example 1
I love my parents, Russell Westbrook and Ariana Grande.
Why this should be corrected:
Though it would certainly be cool to have Russell Westbrook and Ariana Grande as parents, it's unlikely that this is what the writer of this sentence intended. It's very easy to pick out that this sentence is incorrect because we know for sure that Ariana Grande and Russell Westbrook don't have a child together, but in other sentences it might not be so easy. Putting the last comma in will clarify that the author actually meant that they liked all of those people separately.
Example 2
Jamie sat on the plane next to Will Ferrell, the famous comedian, former SNL star and a large German shepherd.
Why this should be corrected:
Clearly Will Ferrell isn't a famous comedian and also a large German shepherd at the same time. This sentence could easily be clarified with a serial comma, which would separate the words and let us know that Will Ferrell is indeed a human and not a dog. Opponents of the Oxford comma would likely say that the sentence doesn't need to add a comma but instead needs to be revised to indicate that Jamie is sitting next to both Will Ferrell and a dog.
Example 3
I will be enjoying cereal, eggs and coffee this morning for breakfast.
Why this should be corrected:
This breakfast is starting to sound appetizing until you get to the word "and." Is the author putting eggs in her coffee? Is she pouring coffee over her eggs? In either case, we have to decline the invitation to brunch at her house. In all seriousness, adding that one little comma at the end clarifies that the writer intended to say she is having coffee alongside of her eggs and not on top of them.
Arguments against using the Oxford comma
For every devotee to the Oxford comma, there is another person who is staunchly against its usage. Why wouldn't someone want to use this tool of language if it makes things easier to understand? An anti-Oxford comma person would argue that it could sometimes lead to more ambiguity in a sentence.
Another anti-Oxford comma argument is that commas can "litter" up a page. Many writers and editors want the most important things to shine through in the text: the words. They argue that spilling commas and dashes and other punctuation marks throughout the text can distract the reader from what is most important and detract from the main idea.
Lastly, anti-Oxford comma arguers say that most ambiguity in sentences with lists can be fixed by simply rewriting them. They argue that the sentences need to be restructured instead of merely adding some punctuation and then claiming that it's no longer ambiguous.
So now that we know some arguments on why we may not want to use it, here are some examples to show us what that might look like. Here's how to fix sentences without the Oxford comma:
Example 1
I love my parents, Russell Westbrook and Ariana Grande.
How this could be corrected without the Oxford comma:
I love my parents, but I also love Russell Westbrook and Ariana Grande.
Instead of adding the last comma, we have added in words that can specifically tell us that Russell Westbrook and Ariana Grande are not the author's parents. We could even take it a step further and query the author to ask why these two thoughts would be connected in the first place. We could also ask her if they could feasibly be separated because they seem to be two completely different thoughts.
Example 2
Jamie sat on the plane next to Will Ferrell, the famous comedian, former SNL star and a large German shepherd.
How this could be corrected without the Oxford comma:
Jamie sat on the plane next to Will Ferrell, the famous comedian and former SNL star, as well as a large German shepherd.
We have corrected the ambiguity of whether or not Will Ferrell was a dog comedian (or a comedian who had possibly turned into a dog) by adding in a few words. Now we know that the author was sitting next to Will Ferrell and a large German shepherd on the plane. We could also take this one step further by asking the author for more detail here. Was this Will Ferrell's dog or did the author just get really lucky to sit by both on her plane ride? Was the dog just allowed to sit without being on a leash? If we simply fixed it with a comma then we still might not have all the information that we need.
Example 3
I will be enjoying cereal, eggs and coffee this morning for breakfast.
How this could be corrected without the Oxford comma:
For breakfast this morning, I will be enjoying cereal and eggs while drinking coffee.
In this sentence we completely rearranged the order of the clauses so that it was less ambiguous what the author was doing. There's no question now if she is putting eggs in her coffee or pouring coffee in her eggs because we know now that she is drinking coffee while eating those breakfast items.
Do I have to use the Oxford comma if I'm not using a style guide?
If you are not using a style guide and are writing something for personal usage, then it's not necessary to use the Oxford comma. The main thing about punctuation is that no matter how you use it, just be consistent. For example, if you are writing something that does not have to adhere to a style guide, you can choose to spell out numerals over 10 if it makes sense for the audience—but just be consistent with your rules. The reason why we have style guides is to maintain a sense of consistency throughout documents so that it's easier for the audience to read. If you are writing something besides a research paper or a piece of news, then just be sure to apply good writing style consistently and ask an editor if you are questioning something.
Pay attention to your style guide
Though you may have your personal opinions about the Oxford comma, it's important to set those aside when you are working with a specific style guide that dictates whether or not it's used. It's also crucial to make sure that you're not just following a style guide blindly and that you are making good writing decisions with every sentence. Confused on whether or not the Oxford comma is making your sentences unclear? Ask a teacher or an editor who can help you sort it out and make your writing clear.