I thought I knew about commas before I started looking into them. It’s been a learning curve. I’ve recently revisited some of my short stories, and there have been a lot of changes.
This concluding article in the series tidies up some odds and ends in situations where commas confuse.
But, and other little words that join things together.
Which versus that (yes, it does relate to commas)
Words that end in –ing
The rule for but is the same as that for and, or, nor, for, so, and yet. (These are called coordinating conjunctions, but you don’t need to remember that.)
We’re back to essential versus nonessential information here. If the conjunction follows a main clause that makes sense on its own, use a comma:
David added more salt, but he still couldn’t eat the spinach.
If both clauses are necessary to make any sense, no comma is needed:
David added more salt but still couldn’t eat the spinach.
There is another way of looking at but, which I find easier to remember.
If clauses have a subject on both sides of the conjunction, there should be a comma.
I phoned Emma earlier, but I haven’t heard back from her.
I phoned Emma earlier but haven’t heard back from her.
If they share the same subject – in this case, I – don’t add a comma.
(Is this a case of adding a comma when you add a subject? Or am I pushing this tip too far?)
What rule applies here?
I didn’t watch the film, because it starred Alfredo Bloggins.
I didn’t watch the film because it starred Alfredo Bloggins.
You might be forgiven for thinking that this is one situation where the discredited ‘pause’ myth might apply. I did, when I came across it. However…
In the first sentence – with the comma – because refers to the whole of the first clause; this was the reason I didn’t watch the film.
But also note that this is added information. The first part of the sentence will make sense without giving a reason why.
In the second sentence, because is essential to the meaning of the whole sentence – it wouldn’t make sense without it. Since this information isn’t added, it wants no added comma.
Which or That?
Whether to use which or that also depends on the information it introduces being essential or nonessential. Once again, added information requires added commas.
Leaves that are green in Spring turn brown in Autumn.
Holly leaves, which are green, don’t drop in Winter.
Grammar Girl offers yet another quick and dirty tip:
You can throw out the whiches without doing any harm.
Witch should help you remember…
Use that to introduce part of a sentence that you can’t throw out. (Note you won’t need a comma with that since it’s not added information.)
Use which when the secondary clause, which gives added information, can be thrown out, leaving behind a complete sentence.
Which brings me to…
Words that End in –ing
Should they have commas in front of them?
Where there is a comma, the –ing word refers to the whole of the preceding clause. It introduces either added information (1) or consequences (2) of the first clause.
The technician mended the computer, using the latest diagnostic program. (1)
The technician mended the computer, ensuring the class could continue. (2)
The words using and ensuring refer to ‘the technician mended the computer’ – NOT to the computer.
When there is no comma, the –ing word refers to the noun immediately preceding it.
The technician mended the computer bearing the OUT OF ORDER sign.
The –ing phrases in the first two sentences add information since the first clause of the sentence would make sense without it. Each –ing phrase required me to add a comma,
In the third sentence, the phrase introduced by bearing identifies the computer so is essential to the meaning of the sentence. No added information means no added comma.
Peter drove the minibus carrying nine passengers.
Peter drove the minibus, carrying nine passengers.
The word carrying identifies the minibus and could be seen as essential to the meaning of the sentence. Is your head spinning yet?
Words ending in –ing can be more complicated than this simple introduction. There is an in-depth article about –ing words of all kinds at
The most exhaustive comma crib in one place must be Purdue OWL; another brilliant resource all-round.
Pauses don’t indicate the need for a comma, but they can offer clues. Don’t put in commas wherever you would pause but you will often pause when you hit a comma if reading a sentence aloud (Grammar Girl again).
This is one good reason for reading your own work aloud when editing.
Reading aloud helps you identify where a sentence doesn’t make the sense you intended, or where too many commas make it difficult to read. When there is little or no scope for ambiguity, commas can be dropped, especially if they’re getting in each others’ way.
In fact, I’m beginning to adopt a new comma philosophy that I haven’t found anywhere else… yet.
If in doubt, leave it out.
Something completely different (tba)