The lowly comma might be one of the most frequently used (and misused) pieces of punctuation in the English language. It has so many uses that it can get confusing trying to keep straight how to use it and how not to.
One of the ways people often get into trouble with comma usage is in joining sentences. Varying your sentence length and complexity is a great way to control the pacing and flow of your writing.
To create a compound sentence by joining two complete sentences, you need more than just a lonely comma, though. If you do that, you end up with a common error known as a comma splice.
X I drove into town to pick up supplies for your birthday cake, the store was out of flour and milk.
The rules for fiction writing are a bit more relaxed than formal writing, but academics and professionals aren’t the only ones who should do their best to avoid comma splices. By choosing nonstandard punctuation usage, you run the risk of confusing or tripping up your reader and distracting them from your message.
In reading the example above, did you notice the slight pause your brain made as it tried to switch gears and finally realized the second part of the sentence was actually a separate thought?
As I said, comma splices are a common error. But how do you fix them?
There are four possibilities, and which you choose depends on the structure and flow of your writing.
Because a comma splice involves the joining of two complete sentences, you could just split them into separate sentences by placing a period at the end of the first and capitalizing the first letter of the second.
This way works best if you’re looking for a strong break between the two ideas or if you’re going for a more staccato rhythm to that section of your writing.
I drove into town to pick up supplies for your birthday cake. The store was out of flour and milk.
Notice how the rhythm and even the emphasis changed when we split the example into separate sentences.
By adding a coordinating conjunction (for, and, nor, but, or, yet, so) after the comma, you maintain the connection between the two sentences and improve the flow of thought.
I drove into town to pick up supplies for your birthday cake, but the store was out of flour and milk.
Notice how the tone changes as the conjunction bridges the gap between the two thoughts.
Many writers avoid the semicolon, either because they don’t understand how to use it correctly or because they feel like it’s too stuffy and belongs only in formal writing. But that’s just not true.
A semicolon is perfect for those instances where a period provides too strong of a break, but a conjunction feels too wordy. When using a semicolon, you want to make sure you’re connecting two complete sentences and that they’re closely related.
I drove into town to pick up supplies for your birthday cake; the store was out of flour and milk.
The flow of the sentences ends up similar to the comma splice, but the semicolon subtly alerts the reader to the start of a new sentence.
If you dislike the semicolon, you probably despise the colon. Few punctuation marks in English are so misunderstood, but there are circumstances where it may just be perfect for the tone and rhythm you want.
Colons can’t be used to join just any sentences, though. Generally, they’re used to introduce lists, amplify a previous word in the sentence, or form structures like ratios and dialogue tags.
But in certain circumstances, they can be used to join two closely related sentences. However, in order for a colon to join two sentences, the first must be a complete sentence, and the second must refer back to or amplify a word, phrase, or thought from the first.
The store was out of baking supplies: they didn’t even have flour.
In this example, not having flour is implied in being out of baking supplies, but the second clause serves to stress the first.
Is a comma splice ever OK?
As with most rules in English, there is an exception to this one, too. It’s rare and should be used sparingly, but there are circumstances where comma splices, though not encouraged, are accepted.
You need a series of three or more short sentences that all share the same subject.
I came, I saw, I conquered.
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You could use semicolons in both examples to achieve a similar rhythm, but if you want less separation between the elements, commas are allowed.
It continually amazes me how we can change the feel, emphasis, and even meaning of our writing with just a few subtle shifts of grammar and punctuation. The endless possibilities are what make English such a vibrant and flexible language.
Rebecca has a passion for helping you fill the world with great literature and making sure said literature doesn't get passed over for the lack of a little editing.