Grammar Girl here.

This is the special Scott Sigler Ancestor episode, and the topic is comma splices. As I've mentioned in previous episodes, Scott is well known for podcasting his first science fiction novel called Earthcore. It turns out that Scott and I have a mutual friend, and Scott asked me if I'd like a review copy of his book and if I'd take a look at his grammar.

Normally, I don't like to use sentences written by real people as examples of bad writing because it seems mean, but Scott practically begged me to be brutal, and the guy uses commas like confetti, so I'm going to use clips from his books to illustrate how not to use a comma. Plus, he killed a character I liked in his book, so it feels kind of good to be mean to him.

Commas are tricky because there are so many different ways you can use them, but one of the most common ways to use commas is to separate two main clauses that are connected by a coordinating conjunction. That just means that when you join two things that could be sentences on their own with a word such as “and,” “but,” or “or,” you need a comma before the conjunction. For example, Squiggly ran to the forest, and aardvark chased the pet peeves. Squiggly ran to the forest is a complete sentence, and Aardvark chased the pet peeves is also a complete sentence. To join them with a comma, you need the word “and” or some other coordinating conjunction. If you just put a comma between them—[wrong] Squiggly ran to the forest, aardvark chased the pet peeves—that's an error called a “comma splice” or a “comma fault.”

Comma splices seem to be Scott Sigler's biggest grammar problem. Here's an example from page 114 of Ancestor, where one of the characters is talking about a cow:

[wrong] Sara obviously named that one, she was a sucker for those old “Happy Days” reruns.
 
It's easy to see in that example why the error is called a comma splice: it's because the comma is used to splice together two complete sentences when that isn't the function of a comma.

The good news is that it's easy to fix a comma splice once you are aware of the problem. Because the two clauses are complete sentences, you can treat them that way and use a period where you had a comma. Sara obviously named that one. She was a sucker for those old “Happy Days” reruns. It's a period's job to separate complete sentences. 

If the two sentences are closely related to each other, as they are in Scott's sentence, you can use a semicolon to connect them without a coordinating conjunction. Sara obviously named that one; she was a sucker for those old “Happy Days” reruns. The semicolon makes sense because the second clause expands on the reasoning of the first clause. He's saying that it's obvious that Sara named the cow because she liked “Happy Days” reruns and the cow is named after a “Happy Days” character.

I hadn't thought about it this way before, but you could consider a semicolon a “sentence splicer” because its job is to splice complete sentences together. (I covered semicolons two weeks ago in episode #42, where you can  learn more about when it's appropriate to use a semicolon if it still isn't clear.)

Sometimes, you can also fix a comma splice by adding a coordinating conjunction. It doesn't work with Scott's sentence because it doesn't make any sense to add an “and” or any of the other coordinating conjunctions. It doesn't make sense to say [wrong] Sara obviously named that one, and she was a sucker for those old “Happy Days” reruns. But if I go back to the sentence from before—Squiggly ran to the forest, and aardvark chased the peeves—you can see that it makes sense to connect those two sentences with a coordinating conjunction and a comma.

Let's take one more of Scott's mangled sentences and see if we can fix it!

This one is from page 29, where he is talking about how one of the characters lured in investors for his "evil plan.”

[wrong] They were getting it, he had them.

So in the comma splice repair kit, we've got periods, semicolons, and coordinating conjunctions.

The period definitely works: They were getting it. He had them.
The semicolon works because the two clauses are related: They were getting it; he had them.
And in this case we can add a coordinating conjunction to fix the problem too: They were getting it, and he had them.

So, I hope you get it! Commas aren't meant to join main clauses all by themselves; to force them into that role is to perpetrate a comma splice. That's bad, but it's easy to fix.

And now, it's finally time for the book giveaway a lot of you have been waiting for. The three prerelease review copies of Ancestor, generously donated by Scott Sigler, go to Mike J, Simone in Ontario, and John in Denver. Thanks again to Scott for donating the books and for making such useful grammar errors.

Questions and comments for me, Grammar Girl, go to feedback@quickanddirtytips.com or the voicemail line at 206-338-GIRL. You can find a full transcript of this podcast at QuickAndDirtyTips.com. This week Money Girl talks about the Solo 401(k), and Modern Manners talks about etiquette at the gym (including steam room etiquette), so be sure to check them out as well as all the other shows. 

Thanks for listening.

Advanced

Here are some other ways to fix a comma splice.

Make one of the main clauses a subordinating clause:

[wrong] Squiggly ran, aardvark hid.
[right] Because Squiggy ran, aardvark hid.

Make one of the main clauses a phrase:

[wrong] Aardvarks are the most noble nocturnal animal, they free us from ants.
[right] Aardvarks--the most noble nocturnal animal--free us from ants.

There are rare specific cases where it is acceptable to join complete sentences using just a comma. Yes, I just said comma splices are allowed in some cases. For example, the authors of the grammar handbook Things Your Grammar Never Told You say it is acceptable to use commas to join very short sentences that are exactly parallel: I came, I saw, I conquered. Strunk & White give similar advice in The Elements of Style. Nevertheless, I don't recommend using commas in this way.