The Oxford comma is a subject of much debate amongst writers with no real consensus about whether you should place a comma or not. The Oxford comma is also known as the serial comma or series comma, is a grammatical method of writing lists.
For example, if using the Oxford comma, you would write, "He counted one, two, three, and four." If you were not using the Oxford comma, then you would write, "He counted one, two, three and four."
To understand why this debate happens, you have to know where the two different rules originate.
History of the Comma
The Oxford comma, also called the Harvard comma, began with Oxford University, and it is a method utilized on many college campuses for writing papers. It is a rule common in many style books used in the United States, including APA Style Manual, The Chicago Handbook of Style, MLA Style Manual, White's Style Handbook, and the US Printing office Handbook of Style.
The Canadian Press and The Associated Press Handbooks (used by journalists) both advise against using a comma in this position. It is notable that though the practice began with Oxford University, the method is more common in the United States than it is with British writers.
In my opinion, the source of confusion is evident. We have two grammatical authorities that are giving different views about what the rule should be. Since I don't foresee the gods of grammar getting together to resolve this issue anytime soon, we mere mortals must learn to deal with it.
Know Your Audience
You may be asking why any of this matters. When I was a young boy in English class, my teacher taught me not to use the Oxford comma, but when I went to college, it was an MLA style campus, so I had to rethink my habits and include it. Those first couple of papers had points deducted because of improper comma usage.
I believe that this is part of the source of the confusion. My English school teacher was a journalism major. She ran the school newspaper, and probably got her degree from a school that taught her to use the AP Style.
When I went to college, it was a rude awakening. I think that many people's opinions start from where you learned grammar. Everyone had a teacher that was educated to either use the comma or not to use the comma. Then they taught all of their students the rule the way that they learned it.
No matter what kind of editor that you are writing for, if you do not punctuate in the manner that your editor expects, then they will consider it to be subpar writing. You need to know your audience and be able to shift between different writing styles to please them, or you need to specialize and write well for a specific audience.
Arguments for and Against
I have heard many of the arguments for or against the usage of this comma. Most of those arguments, in my opinion, can be resolved with clear, concise writing with or without the comma's inclusion. For example, both sides debate that the comma usage or lack thereof can create ambiguity.
A sentence that says, "I talked to my parents, Uncle and Aunt," is ambiguous. Where you talking to the uncle and aunt of your parents, or did you speak to all three people? A supporter of the Oxford comma would say that using the comma eliminates the ambiguity saying more clearly that you talked to all three people.
Clear Concise Writing
However, this can be resolved simply with clear, concise writing. By shifting two words to make the sentence say, "I talked to my uncle, aunt and my parents." It now does not matter if the comma is present. Keep in mind if you need to switch between different styles of writing.
If you do not know your audience or if you can expect an audience of mixed backgrounds, then I recommend avoiding sentences with long lists. Once again, clear, concise writing can save you.
Often it is better to break lists up. Turning them into complex sentences or even two sentences is better than readers getting a negative opinion of your writing. For example, you might say, "I spoke to my parents last night, and I talked to my uncle and aunt.
Conclusion
No matter where you stand on the usage of the Oxford comma, remember that if you find yourself in a situation where the rules differ from what you are used to, then you will need to adapt. There is no sense in having your assignments lose points or your submittals rejected over something so trivial. You may believe that you are right and the editor or teacher is wrong but it isn’t likely that you are going to win this argument. So learn to work around it.