Comma Splices and How to Avoid Them

Like a botched Apparition spell, a comma splice happens when a comma is unequal to the task of carrying you from one clause to another.

Pierre snorted like a pig every time he laughed. He could hardly help it given his physiognomy.

• Pierre snorted like a pig every time he laughed, he could hardly help it given his physiognomy. X

A comma is not strong enough to join what would otherwise be two complete sentences.

• Pierre snorted like a pig every time he laughed. He could hardly help it given his physiognomy. ✓

A period is often the cleanest fix for a comma splice. There is nothing wrong with short sentences. However, if you want to convey a tighter relationship between your clauses—cause and effect, for example—you can use a coordinating conjunction, dash, colon, or semicolon instead.

• Pierre snorted like a pig every time he laughed, but he could hardly help it given his physiognomy.
• Pierre snorted like a pig every time he laughed—he could hardly help it given his physiognomy.
• Pierre snorted like a pig every time he laughed; he could hardly help it given his physiognomy.
• Pierre snorted like a pig every time he laughed: he could hardly help it given his physiognomy.

Demons have bad days like the rest of us, and sometimes they need a hug.

Coordinating Conjunctions

Coordinating conjunctions are the joining words and, or, but, so, yet, for, and nor. Using them makes the relationship between your clauses explicit, which is no bad thing.

• Demons have bad days like the rest of us, sometimes they need a hug. X
• Demons have bad days like the rest of us, and sometimes they need a hug. ✓

See Commas and Conjunctions for more.

Dashes

Dashes have a lot of uses, but in this case their interruption suggests an aside or a punchline, like an elbow to the ribs.

• Euphemia was a canny card sharp, even Death couldn’t beat her. X
• Euphemia was a canny card sharp—even Death couldn’t beat her. ✓

See How to Use Dashes for more.

Colons and Semicolons

Colons introduce, while semicolons join. Use a colon when the second clause explains or expands on the first. Otherwise, use a semicolon.

• Giacomo’s true nature was obvious in hindsight, he’d always avoided garlic, churches, and sunlight. X
• Giacomo’s true nature was obvious in hindsight: he’d always avoided garlic, churches, and sunlight. ✓ 
• It couldn’t have been easy, no wonder there were so few vampires in Italy. X
• It couldn’t have been easy; no wonder there were so few vampires in Italy. ✓

See Colon vs. Semicolon for more.

Euphemia was a canny card sharp—even Death couldn’t beat her.

All that said, if your clauses are very short, and if their structures match, you can get away with only a comma between them.

• I came, I saw, I conquered.
• Mum was in the orchestra, Dad in the ballet corps.
• She played, he danced.

What you don’t want to do is make your sentences flimsy paperclip chains of clauses hooked together by commas. Clarify your thoughts, then use the appropriate punctuation.

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