When it comes to commas, there are four kinds of author: those who use them correctly, those who use too few, those who use too many, and those who have about the right number but in the wrong places. I refer to this last kind of author as the “Jackson Pollock,” because they litter their manuscripts with commas at random, like paint splashed on a canvas.
Back when I worked as a copy editor for Hodders, there was one author we worked with who had no idea about where to put her commas. We had her under contract for a series, unfortunately, and after the first couple of books I started using find-and-replace to strip out all the commas before I even looked at the book, because I knew the vast majority would be in places they didn’t belong.
Foolishly, I mentioned to my boss that I was doing this, and--even more foolishly, in my opinion--my boss mentioned it to the author, who threw a fit. I was firmly forbidden from using the nuclear option, and had to go back to removing them one at a time.
There are four kinds of authors, and there are also four kinds of commas. There are commas you must use, commas you must not use, commas you can use if you want, and commas that there’s a rule about, but hardly anyone knows the rule, so you’ll get away with not following it most of the time.
I won’t be talking much about the commas you can use if you want, the ones that you can put in or leave out and still be correct. Whether you use them or not is a matter of style and personal taste, and a way of varying and controlling the pace of your sentences. It’ll give your editor something to change if you get everything else right, so he or she feels useful. Nor will I be talking at length about the arcane comma rules that only advanced editors and grammarians know or care about.
Much more important are the commas without which your sentences don’t flow properly, and the commas which ought not to be inserted.
Do Not Do: Comma Before Main Verb
When I go through a book and mark errors, the most common comment I make is usually “omit comma”. Therefore, the kind of comma I want to talk about first is the one which ought not to be inserted.
Notice what I didn’t do in that last sentence. I didn’t say:
The kind of comma I want to talk about first, is the one which ought not to be inserted.
This is probably the most common comma error I see: the excess comma before the main verb. Not only is it not needed, it’s incorrect.
From a high-level view, that last example sentence is grammatically the same as this one:
Henrietta is an aardvark.
“The kind of comma I want to talk about first” is a noun phrase, grammatically equivalent (at a high level) to “Henrietta”. There is no justification for separating it from its main verb with a comma. None.
I suspect that the cause of people’s confusion on this point is this kind of sentence:
Henrietta, the person you spoke to yesterday, is an aardvark.
That example does have a comma before the main verb. However, it’s the second comma in a pair. They’re parenthetical commas, and (as “Henrietta is an aardvark” demonstrates), you could lift out everything inside them and the sentence would make sense and be grammatically correct.
You could use dashes instead:
Henrietta--the person you spoke to yesterday--is an aardvark.
Henrietta (the person you spoke to yesterday) is an aardvark.
For stylistic reasons, to maintain the flow, you’d probably use commas, though.
Do Not Do: Comma After Last Adjective
Less common, but still something I’ve seen several authors do, is this:
Henrietta was a small, grey, aardvark.
In some cases this is because you originally had three adjectives and have taken out the third one, but left the comma after the second. But I know at least one author who has this bad habit of consistently placing an unnecessary and incorrect comma between the last adjective in a list and its noun.
This is probably the place to mention one of those more obscure comma rules. Don’t worry too much about it if you struggle with the basics, but if you usually get commas right, here’s something you can do to improve even further:
If you’re using several adjectives (like “small” and “grey”) and the order that you have them in is the only one that makes sense, you don’t need the comma between them. Likewise if you can’t join them with “and”. You wouldn’t say “Henrietta was a grey, small aardvark”, or “Henrietta was a small and grey aardvark”. In effect, what is happening here is that “grey aardvark” is acting as a loosely joined unit, so the comma can be dispensed with entirely, leaving you with:
Henrietta was a small grey aardvark.
Colours and substances often trigger this rule (an old wool sweater, a wide blue ocean). But if you have a couple of colours (a green-eyed, red-haired woman) the comma belongs in between, since you could swap the order or replace the comma with “and”.
This is known as the “coordinate commas” rule. The adjectives which are of equal rank and importance, and can be swapped round or joined with “and” instead of commas, are coordinate adjectives.
Don’t worry too much if you can’t quite grasp this rule or if you forget it occasionally. It’s one of the more obscure comma rules, and most people won’t notice if you break it.
Do Not Do: Commas Around the Name
Here's another common comma error that I see, especially from journalists and in the blurbs of indie books:
Prominent aardvark, Henrietta Wibsley, announced today that she would be travelling into space.
These commas are unnecessary and incorrect, at least in a sentence phrased this way. I suspect that they've been incorrectly imported from this kind of phrasing:
The world's most prominent aardvark, Henrietta Wibsley, announced today that she would be travelling into space.
Here, "Henrietta Wibsley" explains who "the world's most prominent aardvark" is. It's another parenthetical comma. You could also say:
The world's most prominent aardvark (Henrietta Wibsley) announced today that she would be travelling into space.
In the incorrect example given above, "Prominent aardvark Henrietta Wibsley" is a noun phrase, and shouldn't be broken up by the comma.
The worst example of this error I ever saw was in a blurb for an indie book, which went like this (identifying details altered to protect the guilty):
"Meanwhile Pinkerton operatives, Detective, Thomas Wright and, Assistant, Colin..."
Sadly, the rest of the book was just as bad, if not worse.
Do Not Do: Comma Splice
A “comma splice” is when you join what should be two separate sentences with a comma, like this:
Joseph stood, he was not going to put up with that from an aardvark.
“Joseph stood” is a complete sentence, and should be written as such. Just because the thought continues into the next sentence is no reason to join them with a comma.
Comma splices betray that you don’t really know what you’re doing when it comes to grammar. They will count heavily against you. Check your work carefully, and ask yourself if you’re joining complete sentences with commas where you should be separating them.
Joining Without Splicing
The problem with comma splices is not that the sentences are joined, but that they're not joined enough. There's no transitional word to indicate what their relationship is. For example:
Try this instead:
Candidates for joining sentences include because and its near-synonyms as, since, considering, therefore, thus; but and its near-synonym however; and and.
You can also break the two sentences with a period, join them with a semicolon, or rephrase the first so that it's not a full sentence:
Henrietta is prominent, she is often thought to speak for all aardvarks.
Because Henrietta is prominent, she is often thought to speak for all aardvarks.
Henrietta is so prominent, she is often thought to speak for all aardvarks.
Those sentences have commas doing what they ought to, separating grammatical units. More on that in the next chapter.