Thursday, April 25, 2013

Writing tips: Beware the comma splice

Comma butterfly image © Copyright Peter Trimming;
licensed for reuse under Creative Commons.

Commas are probably the most abused punctuation mark in English today, and probably the most overused, too. Here are a few tips to make them easier to use correctly.
Commas separate parts of a sentence:

  • items in a list 
  • phrases
  • clauses.

Don’t leave out commas from your writing. They represent the pauses in speech, and give readers a chance to take a breath — important even if we’re not reading aloud.

However, don’t overuse them, either. I remember one educational film made in the UK in (judging from the awful clothing) the mid-70s, that said overusing commas made text seem like the writer had hiccups!

  • The carpet, when delivered, will be laid by our approved carpet layers, who are, in your area, Thomas and Jones, Inc.

Read that aloud with a pause at every comma, and you’ll hear what I mean.

Think of a comma as a brief pause to make it clear what ideas belong together.

  • Since this is a new responsibility for the agency, based on new legislation ...

Which is different from

  • Since this is a new responsibility, for the agency based on new legislation ...

Image source: Moblog, creative commons

Those splices won’t hold!

Commas are not strong enough to separate complete thoughts. For that, you need a period — or at least a semi-colon. Sometimes, even talented writers will use commas in situations that need periods. This is called the “comma splice.”
Here are some examples from a book I helped to edit a little while ago, doctored somewhat to protect the innocent. I mean, guilty.

  • The woman in the red dress was no common thief, she’d seen too much, taken too much.

That’s two complete thoughts, so it should be two complete sentences. Replace the comma with a period and capitalize “She’d,” and you have a grammatically correct sentence.

The next example has the same problem:

  • Raising the money took priority, nothing could get in the way of that.

  • Sometimes, though, we don’t want to use the full stop, as the Brits like to call the period. There are cases where the period does not express what we are trying to say.

    • Too bad if the marine lived, he had learned long ago that least dangerous soldier was a dead soldier.

    These are two separate thoughts, but in this case, they’re closely related. Replace the comma with a semi-colon. Same with the next example:

    • Not so long ago, he thought Karen would be the only one for him, now barely a thought of her came into his head.

    The simple way to remember it is this: if a group of words has a subject and a verb, it’s a sentence. That means it also needs to begin with a capital letter and end with a period. Even two words can be a complete sentence:

    • Johnny ran.

    An imperative (command) sentence can be one word:

    • Run!

    And that means, end it with a period. Most of the time. You can also use question marks for questions, and occasionally exclamation marks, too. But use those rarely.

    Link related sentences with a semi-colon, but again, go lightly with them. They’re like habanero peppers — terrific when they’re used sparingly.

    For more on sentences, check out my blog post from last November. And if you have a question, put it in the comments, or send me an email or a tweet.


    1. The important thing to remember with the semi-colon is that the two clauses it separates must be independent.

    2. The term "comma splice" was familiar but couldn't remember what it meant. Thanks for the refresher!

    3. Anonymous2:07 PM

      I confess I'm pretty guilty of comma overuse. I need to fix this.

    4. I have trouble identifying the clauses that need commas to separate them and the ones that don't. This is definitely an area with which I struggle. (I really wanted to put a comma before the and...)