Comma splice

Before I discuss comma splices I will briefly explain run-on sentences, since there is some overlap in definition. A run-on sentence – also known as a fused sentence – is a sentence in which two or more independent clauses run together, i.e. the clauses are not joined by a conjunction or by punctuation:

The tests were inconclusive I didn’t know what to do next.

Everyone was ready however there were unforeseen delays.

Such sentences don’t stop, or pause properly, when they should. Neither do sentences with a comma splice, which occurs when two or more independent clauses are joined only by a comma:

The tests were inconclusive, I didn’t know what to do next.

Everyone was ready, however there were unforeseen delays.

Some grammarians consider comma splices as a type of run-on sentence; others distinguish them but discuss them together.

The comma splice is also called a comma error, comma blunder, and comma fault, but I find these terms too judgemental. Comma splices can be fine in fiction, poetry, letters and informal writing in general, where they often reflect spoken English and join clauses that are short, connected by subject or content, and unlikely to be misconstrued:

It wasn’t broken, it needed new batteries.
The shops were all closed, I couldn’t buy milk.

Commas are weak marks: they can separate elements within a clause, but they are not always considered strong enough to separate independent clauses. Comma splices (and run-on sentences) can draw readers into a second independent clause before they know that the first one is finished.

It is therefore preferable in many kinds of formal writing to separate such clauses with a conjunction or a stronger punctuation mark: a colon, semicolon, full stop or dash will supply the necessary pause. Simple rearrangements are another option.

It wasn’t broken, but it needed new batteries.
It wasn’t broken – it needed new batteries.

The shops were all closed, so I couldn’t buy milk.
As the shops were all closed, I couldn’t buy milk.
The shops were all closed; I couldn’t buy milk.
I couldn’t buy milk because the shops were all closed.

The tests were inconclusive, and I didn’t know what to do next.
Since the tests were inconclusive, I didn’t know what to do next.
The tests were inconclusive; I didn’t know what to do next.
The tests were inconclusive. I didn’t know what to do next.

All of these revisions are fine, and you can probably imagine many others. Which approach you choose depends on what suits the context, what tone and rhythm you want to convey, and so on.

Comma splices were more common in 18th and 19th century English, when they were not considered ungrammatical. Although modern English is more rigorous, comma splices have been used by authors like William Faulkner, Samuel Beckett, E. M. Forster, John Banville, Iris Murdoch, E. L. Doctorow, Hermann Hesse, and E. B. White (he of Strunk & White). Here’s White, in a letter from 1963:

Tell Johnny to read Santayana for a little while, it will improve his sentence structure.

No one could reasonably find fault with this comma splice. Its informality is obvious, and the sentence style is easy and plain.

Comma splices are especially popular with children, who tend to use lots of them in long rambling sentences. If you use comma splices in fiction or informal writing and you know what you’re doing, they should be fine. If you use them in student papers, official reports and the like, they may not. You can avoid them by using the techniques shown above.


For lots more discussion, and many examples of comma splices from literature, see my follow-up post “Oh, the Splices You’ll See!

17 Responses to Comma splice

  1. […] is often implicated in commas splices, which I describe here. They are also mentioned in the final bullet point of my post on semicolons, which has additional […]

  2. Sean Jeating says:

    ‘I was unable to buy milk because the shops were all closed.’

    Stan, so there’s no comma before ‘because’, as a rule?
    And: if so, does there exist a ‘rule’ for any exceptions?

  3. Stan says:

    Sean: Rather than a rule, there are differing styles. The “close” style tends towards heavy punctuation, and in extreme cases can be unsightly and distracting. The “open” style takes a lighter approach, but can be so light that it introduces confusion and ambiguity.

    In the example you quoted, a comma can be added after milk with no difference to meaning(,) and just a slight difference to rhythm and tone.

    Commas and other stops have two main functions: grammatical, to help structure a sentence; and rhetorical, to refine its meaning or adhere to a certain style (such as might be required by one’s publisher, for example).

  4. Sean Jeating says:

    Thanks, Stan.
    Punctuation is such a helpful tool; the more when properly/skilfully used and not after the ‘saltshaker’-method.

    Not sure, if it was a sharp-tongued critic or Günter Grass poking fun at himself who once analogously stated: ‘A sentence in which one would not find at least five semicolons, is no sentence.’

  5. Stan says:

    You’re welcome, Sean. I will write more about punctuation in future posts. It is a crucial part of clear writing, yet it is poorly understood. This morning I edited a sentence 45-50 words long, with a faulty comma after the first word and no punctuation at all after that!

  6. Claudia says:

    This is very helpful. Sometimes, I get rid of the problem by shortening sentences. Often, the French ‘virgule’ is used differently than in English. It compounds my perplexity..

  7. Stan says:

    Glad it helped, Claudia, and as I said, there is more to come.

    It is challenging enough to keep track of the finer points of punctuation in one language, let alone in two or more! In English the word virgule denotes “/”, the mark commonly known as the slash. Barre oblique en Français?

  8. Claudia says:

    Slash est ‘barre oblique’ dans le language informatique, ou barre de fraction dans mes vieilles Grammaires! Je viens de trouver un excellent site avec Google: “French Punctuation: Key differences with English.”

    This is a lot more fun than worrying about the low interest my bank is offering me presently for my small investments! Nevertheless, our banks are very solid in Canada. None needed help from our government, as in other countries. The change of subject was to practise the comma!…

  9. Stan says:

    It was good practice! You are lucky to have solid banks. Ours are about as solid as this.

    Thank you for clarifying the French terms. Can you direct me to the website comparing English and French punctuation?

  10. Claudia says:

    I never know if one says practice or practise…

    I can’t send you to links the easy way you send me to yours’. My son will try to teach me this week. But if you Google: French Ponctuations: Key differences with English, you will get what I saw. Also: French Writing and Mechanics which covers any question you might have. I like those two posts because they use English to explain the problems, and give you good examples. Plenty more to choose from with Google. Also Vikipedia is fairly good about French Ponctuations.

    Bonne chance et bonne journée.

  11. Claudia says:

    Just look at your bank! A pity….My sympathy!

  12. Stan says:

    Ah, I found it. Thanks Claudia. To create a hyperlink, type:
    [a href=”http://…..”]name of page[/a]
    but with HTML brackets instead of square brackets.

    Your practices and practises seem fine so far! Usage is mixed, especially across the Atlantic. The noun is almost always practice in British English, and usually in U.S. English. The verb is almost always practise in British English, and usually practice in U.S. English.

  13. […] Some random observations. Because there is no stemming, the cloud includes common and commonly; usage, use, useful, and used. Certain words appear because of their prominence in posts dedicated to them, such as however, principal, quality, and mwdeu. Others appear because they feature a few times in a set phrase, such as death in Blue Screen of Death, and splices in comma splices. […]

  14. […] a previous post I explained what comma splices are, and how and when to avoid them. Now I’d like to share a few […]

  15. […] Stan also has some good advice on how and when he’d use or avoid comma splices, though our opinions differ a bit. Rate […]

  16. Warsaw Will says:

    @Sean Jeating – the way we teach it in TEFL is that if the main clause comes first, you don’t need a comma – so – ‘I was unable to buy milk because the shops were all closed.’ is fine. But if the subordinate clause comes first, then we need a comma – ‘Because the shops were all closed, I was unable to buy milk.’ And I think this pretty closely reflects how we use pauses in speech.

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