And why sometimes, it’s not even an error.
What Is a Comma Splice?
First, we have to figure out what a comma splice is. Maybe you’ve never even heard of the problem. It sometimes also goes by the name “comma fault” or “comma error,” but I think “comma splice” makes the most sense because the problem is using a comma to splice together things that the comma wasn’t meant to splice or join.
Read More About Other Janus Words Like “Splice”
For example, an independent clause is something that could stand on its own—essentially a sentence.
Aardvark enjoys fishing.
If you want to splice together two independent clauses, you aren’t supposed to use a comma. It’s not strong enough. Doing so is the error called a comma splice.
Aardvark enjoys fishing, Squiggly chooses a different lake for their vacation every year. [That’s a comma splice error because the comma is joining two independent clauses.]
If you want to join two independent clauses, you can use a semicolon:
Aardvark enjoys fishing; Squiggly chooses a different lake for their vacation every year.
You can use commas and conjunctions:
Aardvark enjoys fishing, so Squiggly chooses a different lake for their vacation every year.
You can add a subordinating conjunction and turn one of the clauses into a dependent clause and then use a comma between them:
Since Aardvark enjoys fishing, Squiggly chooses a different lake for their vacation every year.
Or you can just use a period and keep them as separate independent clauses:
Aardvark enjoys fishing. Squiggly chooses a different lake for their vacation every year.
But, you aren’t supposed to use a comma. Joining two independent clauses with a comma is called a comma splice, and that’s usually considered an error.
Next: A Revelation! Why So Many People Are Confused About Comma Splices
Why Are So Many People Confused About Comma Splices?
The examples I just gave are the simple kind of sentences you’ll see in most explanations of comma splices, but because they’re so simple, they don’t show you the whole problem.
Sometimes Participial Phrases and Clauses Can Look a Lot Alike
I was pondering why people have so much trouble identifying comma splices when I started browsing through a new book that had just arrived in the mail. Penguin sent me a copy of Brooks Landon’s Building Great Sentences, and it had a short, half-page section that answered the question perfectly: He points out that it’s exceedingly common for authors to put a phrase after a comma, and that’s not an error. It’s good writing style. A phrase is fine after a comma, but a lone clause is not; and many people (even English majors) don’t know the difference between a phrase and a clause. (1)
A clause can stand alone as a sentence, and a phrase cannot.
Here are examples of phrases that appropriately come after an independent clause and a comma:
It had started raining again, fat drops hitting the window like pebbles. (A Memory of Light, Robert Jordan & Brandon Sanderson)
It crouches low and creeps toward me, its lips peeling back from its white teeth. (Divergent, Veronica Roth)
Those parts that come after the comma are all phrases, participial phrases to be exact because they contain a participle—which is something that looks a lot like a verb, but isn’t. The important thing to note is that none of those phrases can stand alone as a sentence. Look at them:
Fat drops hitting the window like pebbles.
Its lips peeling back from its white teeth.
Those shouldn’t sound like sentences to you. They would be sentences if you replaced the participle with a real verb (fat droplets hit the window like pebbles, instead of hitting the window, for example), but they aren’t sentences or independent clauses as they are written. Even though they look like sentences, they’re actually phrases, which means they’re allowed to follow a clause and a comma. No comma splices here.
Next: More Examples and the Role of Appositives
Web Bonus: More Examples
Note that the examples above all use a noun or pronoun followed by a participle, making them particularly sentence-like and confusing. In all of the following examples (except for the first three), the participle directly follows the comma. The same principle applies to both though: the words after the comma could not stand on their own as a sentence. They make a phrase, not a clause, and it’s fine to join an independent clause and a phrase with a comma.
He watched the sun as it continued to sink behind the trees, his eyes struggling to stay open as the darkness gathered around him. (Timubktu, Paul Auster)
Dobser hung in his bonds, facing the wall, his ears plugged by Pevara’s weaves. (A Memory of Light, Robert Jordan & Brandon Sanderson)
It stood open a crack by intention, the sturdy lock on the outside left hanging as if someone had forgotten to close it. (A Memory of Light, Robert Jordan & Brandon Sanderson)
Pevara reacted immediately, throwing weaves at the two men while forming a thread of spirit. (A Memory of Light, Robert Jordan & Brandon Sanderson)
Half a dozen swallows darted back and forth in the middle distance, skimming the field as they combed the air for mosquitos. (Timubktu, Paul Auster)
The book she had been reading was under her pillow, pressing its cover against her ear as if to lure her back into its printed pages. (Inkheart, Cornelia Funke)
I slowly crept from the bushes to the back door, checking the handle to see if it was unlocked. (Apocalypsis, Elle Casey)
I started backing up, getting ready to run. (Rosemary and Rue: An October Daye Novel, Seanan McGuire)
The light fixed to the front of the train clicks on and off as the train hurtles past the school, squealing on iron rails. (Divergent, Veronica Roth)
Appositives Often Follow a Clause and a Comma
Confusing participial phrases with clauses is one reason you might be creating commas splices. Another reason could be appositives. You’re also probably used to seeing appositives after commas.
An appositive is a noun or noun phrase that’s placed next to another noun or noun phrase to help identify it. (2)
Here are two examples:
It always took him a few moments to find his way out of that other world, the labyrinth of printed letters. (Inkheart, Cornelia Funke) [“The labyrinth of printed letters” is a noun phrase that tells you more about that other world.]
My curiosity is a mistake, a betrayal of Abnegation values. (Divergent, Veronica Roth) [“A betrayal of Abnegation values” is a noun phrase that tells you what the mistake was.]
Again, the important distinction is that the appositives after the comma couldn’t stand alone as sentences by themselves. They’re weak enough to be joined to the main clause by a comma.
Remember this rule: If you have a main clause—something that can stand alone as a sentence—and you put a comma after it, what comes after that comma should not be able to also stand alone as its own sentence. If it can, you’ve created a comma splice.
Next: The Exceptions Are Enough to Drive You Crazy
The Exceptions Are Enough to Drive You Crazy
Finally, you could be confused about comma splices because there are a ton of exceptions to the rule.
You will see many, many examples of comma splices in published literature, for example. Edited literature. Famous literature. In her book Eats, Shoots & Leaves, Lynne Truss says, “[S]o many highly respected writers adopt the splice comma that a rather unfair rule emerges on this one: only do it if you’re famous.” She goes on to name Samuel Beckett, E.M. Forster, and Somerset Maugham as famous splicers. (3) Language blogger Stan Carey has compiled on his site an almost overwhelmingly long list of comma splices from authors whose names you’d recognize.
Further, quite a few usage guides allow comma splices in some situations, making it almost a style choice. For examples, The Elements of Style says, “A comma is preferable when the clauses are very short and alike in form, or when the tone of the sentence is easy and conversational.” (4) Their example is
Man proposes, God disposes.
This rule would also cover the famous sentence “I came, I saw, I conquered.”
Usage writers Barbara Wallraff (5) and Bryan Garner (6) also both allow comma splices in similar circumstances, and The New Fowler’s Modern English Usage doesn’t outright approve of comma splices but notes that they are common in both old and new literature. (7)
Further, Wallraff, in her book Word Court, adds the less commonly seen, but I think reasonable suggestion that a comma can be used to join independent clauses when “the whole point of two clauses is to contrast negative and affirmative assertions.” To me, this is consistent with other instances in which you’re allowed to use a comma to show contrast. (5)
Her example is the sentence “It’s not a comet, it’s a meteor,” and it made me feel better about one of the sentences @cbee submitted as an example of a comma splice she had seen online:
The Editor and I don’t argue, we discuss. (8)
It didn’t annoy me,* and I felt like it was an appropriate use of a comma, but at first I couldn’t figure out why. Then I realized that it fit the comma-for-contrast rule. If I came across this sentence, I wouldn’t mark it wrong.
But @cbee would, and it does fit the simple definition of a comma splice.
That’s the funny and frustrating thing about comma splices and many topics in English usage—once you start digging, the rules aren’t as black and white as you thought, and they can hinge on subjective points such as what’s informal, or what’s short enough, or what’s enough contrast.
My quick and dirty tip is to learn to recognize basic comma splices and avoid them, but the more nuanced answer is that when you’re presented with a sentence that might be allowable under all the comma splice exceptions out there, think about the risks you’re willing to take. Does it matter to you whether some people will think you’ve made a mistake? Could you get in trouble if people think you’ve made a mistake? Or do you feel strongly that your sentence needs a comma instead of some other punctuation or even that taking out the comma will change the meaning? Weigh the benefits and risks, and if you’re comfortable with the balance, use a comma splice when it makes your writing better.
Mignon Fogarty is the author of the New York Times bestseller, Grammar Girls' Quick and Dirty Tips for Better Writing.
1. Landon, B. Building Great Sentences. Penguin. 2013. p. 75.
2. American Heritage Guide to Contemporary Usage and Style. Houghton Mifflin Company. 2005. p. 37.
3. Truss, L. Eats, Shoots & Leaves. Gotham Books. 2003. p.88.
4. Strunk, W. Jr. and White, E.B. The Elements of Style. Pearson Education, Inc. 2000. p. 7.
5. Wallraff, B. Word Court. Harcourt, Inc. 2000. p. 290.
6. Garner, B. “Run-On Sentences,” Garner’s Modern American Usage, 3rd edition. Oxford University Press. 2009. p. 724.
7. Burchfield, R.W., ed. The New Fowler’s Modern English Usage. Oxford University Press. 1996. p. 162.
8. Lopp, M. “A Story Culture.” Rands in Repose. February 8, 2010. http://www.randsinrepose.com/archives/2010/02/08/a_story_culture.html (accessed June 11, 2013).
*Except for the capitalization of “Editor,” but that’s a different topic.