When writing lists, there are two different conventions for what to do before the final item:
- Lions, tigers and bears are charging toward us from all directions.
- To fend them off we will need rifles, pepper spray, and dynamite.
I strongly prefer the second approach, where the final item is set off with a comma, and not just because of where I did my M.Phil.
I have heard some people argue that the commas in a list are stand-ins for the word ‘and’. Instead of writing “life and liberty and the pursuit of happiness”, we should therefore write “life, liberty and the pursuit of happiness”. To add a comma between “liberty” and “the pursuit of happiness” while keeping the “and” is redundant.
I can see the point of this argument, but I think it takes too mechanical a view of language. The purpose of every element of language is to convey ideas and – James Joyce aside – it is usually best to do so clearly. The Oxford comma is very clear. The writer has a list of items, and each item is separated from each other item by means of a comma. In the event of a higher level list, with items separated by semicolons, the final semicolon would surely not be omitted:
His crimes were many: some related to property, like theft and burglary; some related to reputation, including many slanders; and some wanton violations of the Law of the Sea, particularly the disregard of established conventions for deciding maritime boundaries.
In this data-driven age, the serial comma is also in keeping with mathematical and computational conventions. The set of prime factors of my telephone number is: {2, 3, 11, 89, 709453}. Comma separated values are also a common way to store and exchange data sets.
My hope is that I have won over a waverer or two to the serial comma approach. If not, can we please at least agree to put only a single space after a period? We do not live in the age of typewriters anymore!