The serial comma – all you need to know

Ah, the serial comma. If there’s one topic that can be relied upon to polarise opinion among language lovers, that’s it. Yet for most people, its niceties are something of a mystery. Also known as the Oxford or Harvard comma, it’s that little flick of the pen or keyboard that some use between the last two items in a list:

Tom, Dick, and Harry

as opposed to

Tom, Dick and Harry.

Some insist that you should always use it; others, that you should never. But, if you look closely (and dispassionately), you can see that the truth lies somewhere in the middle. Here’s why.

Damned if you (always) do

If you always use the serial comma, then you’ll eventually say something ambiguous or confusing. Like this:

I admire my dad, Marcello Mastroianni, and Sophia Loren.

The serial comma makes it look like Mastroianni is my dad: the two commas form a pair, creating an appositive, making “Marcello Mastroianni” seem a synonym for “my dad”.

Some may say it’s obvious that Mastroianni isn’t my father, that you can always infer the correct meaning from the context. Consider this:

I admire my dad, John Lawrence, and Sophia Loren.

Unless you happen to know that John Lawrence is my uncle, how can you decipher that? Anyway, why should you have to? It’s our duty, as proper professional writers, to make the meaning clear to our readers and not to subject them to an unnecessary cognitive load.

Damned if you (always) don’t

We should always shun the serial comma, then? Not so fast. Try this:

I admire my parents, Marcello Mastroianni and Sophia Loren.

Now it looks like Mastroianni and Sophia are my parents. And, to debunk the “it’s always clear from the context” theory again, the problem persists with:

I admire my parents, Derek Lawrence and Kathryn Lawrence.

(Kath is my auntie.)

Use the serial comma when necessary; omit it when necessary.

When you really ought to omit it:

  • When the second item in a list could be mistaken for a synonym for the first (as with the “my dad” example).

When you really ought to use it:

  • When the second and third items in a list, taken together, could be mistaken for a synonym for the first (as with the “my parents” example).
  • To make clear which words form part of the second item in a list and which form part of the third: cannelloni, burger, and chips and dips vs cannelloni, burger and chips, and dips (Otherwise, the chips become something of a moveable feast.)
  • To clarify that an adjective modifying the second item in a list doesn’t also modify the third: boys, old men, and women (the women aren’t necessarily old). You could rewrite as boys, women and old men, although I wouldn’t with boys, old men, and dental hygienists, where the longest element works best at the end, for reasons of rhythm
  • To emphasise a pause in a sentence written to be spoken out loud, e.g. for a dramatic voice-over: The ERR requisitioned books, artworks, and political material.

What about the rest of the time, when it doesn’t matter either way? Some style guides, like the Economist, favour omitting it; others, like the Oxford University Press style want it in. American writers tend perhaps to use it more than Brits do.

But where it doesn’t do anything – anything at all, as in Tom, Dick, and Harry (where “and” already separates the last two words) – why use it? What is the virtue in a consistency for consistency’s sake, of using something even when it has no function? Omit needless words, someone once said, so omit needless punctuation, too.