In Sleeping Dogs Don’t Lay, authors/grammarians, Richard Davis and Richard Lederer, write, “There’s a belief in art circles that Rodin’s ‘The Thinker’ was trying to remember where he left his pants. We have it on good authority that he was really trying to decide whether to use a comma before and in a series.”
The Thinker isn’t alone. There’s no agreement among usage experts, grammarians, or publishers regarding this kind of comma. The serial comma is also well-known as the “Oxford Comma.”
Oxford explains the name saying the use of a comma before any conjunction that joins the final element to the rest of the series is, “the house style of Oxford University Press.” Although Oxford concedes such commas are, “often superfluous,” it still recommends that final comma.
Had The Thinker consulted the London Times, he’d have been told, “Avoid the so-called Oxford Comma.” Fowler agrees, advising comma use before ‘and’ only when there’d otherwise be ambiguity.
The Dictionary of Contemporary Usage is of the opinion that serial commas should be used only “sometimes.” This source believes such a comma “has long been abandoned by newspapers although it’s retained by textbook and reference book editors.”
So, let’s check style manuals — those references journalists use so they might follow their publications’ styles. CP Style advises, “Put commas between the elements of a series but not before the final and, or nor unless to avoid confusion.” Conversely, the highly regarded Chicago Manual of Style says, “When a conjunction joins the last two elements in a series, a comma is used before the conjunction.” Remember, Chicago Manual is more widely used by book publishers than by newspapers.
Grammar books of the past advised the use of that final comma. My oldest grammar, the 1899 Public School Grammar, advises, “When a number of words or pairs of words or phrases of the same kind, and having the same relation come after one another, each is followed by a comma; as, ‘The reading, spelling, and writing were satisfactory.’”
Eighty-eight years later, in 1987, we find identical advice. New Webster’s Grammar Guide states, “A comma should always be placed before the conjunction joining the last two members of a series.”
Sleeping Dogs Don’t Lay (1999) agrees: “Use commas to separate items in a series of three or more even if the last item is preceded by and.”
Eats, Shoots and Leaves (2003), a text whose very title evokes comma controversy, points out differences between British and U.S. comma usage. Author, Lynne Truss, says, “In Britain ... standard usage is to leave it out ... In America, conversely ... standard usage is to leave it in.”
Truss, who is British, adds, “One shouldn’t be too rigid about the Oxford Comma. Sometimes the sentence is improved by including it; sometimes it isn’t.”
The choice is yours. Use that final comma or omit it. As for me, I use the Oxford Comma even though I do follow CP Style for the most part.
Note: A conjunction is a “joining word,” a part of speech that connects words or constructions, e.g., and, or, but, if, etc.