Although acceptable in some languages and compulsory in others (e.g. Bulgarian or French), comma splices are usually considered style errors in English. Some English style guides consider comma splices appropriate in certain situations, such as when being poetic or with short similar phrases.
According to Joanne Buckley, comma splices often arise when writers use conjunctive adverbs to separate two independent clauses instead of using a coordinating conjunction. A coordinating conjunction is one of the seven words: for, and, nor, but, or, yet, so. A conjunctive adverb is a word like furthermore, however, or moreover. A conjunctive adverb and a comma (or a conjunctive adverb between two commas) is not strong enough to separate two independent clauses and creates a comma splice; only semicolons and periods are strong enough to separate two independent clauses without a conjunction. For example, the following sentence contains a comma splice with a conjunctive adverb:
There is no admission fee, however, you will be responsible for any food you order.
Grammarians disagree as to whether a comma splice also constitutes a run-on sentence. Some run-on sentence definitions include comma splices, but others limit the term to independent clauses that are joined without punctuation, thereby excluding comma splices.
Strunk & White notes that splices are sometimes acceptable when the clauses are short and alike in form, such as:
The gate swung apart, the bridge fell, the portcullis was drawn up.
The famous sentence I came, I saw, I conquered falls into the same category.
We are all accustomed to the … conjoined sentences that turn up from children or from our less literate friends… Curiously, this habit of writing comma-joined sentences is not uncommon in both older and present-day fiction. Modern examples: I have the bed still, it is in every way suitable for the old house where I live now (E. Jolley); Marcus … was of course already quite a famous man, Ludens had even heard of him from friends at Cambridge (I. Murdoch).
The comma splice is often considered acceptable in poetic writing. The editors of the Jerusalem Bible translate Isaiah 11:4 as:
Lynne Truss observes: "so many highly respected writers observe the splice comma that a rather unfair rule emerges on this one: only do it if you're famous." She cites Samuel Beckett, E. M. Forster, and Somerset Maugham. "Done knowingly by an established writer, the comma splice is effective, poetic, dashing. Done equally knowingly by people who are not published writers, it can look weak or presumptuous. Done ignorantly by ignorant people, it is awful."
Comma splices are considered acceptable by some in passages of spoken (or interior) dialogue, and are sometimes used deliberately to emulate spoken language more closely.
Simply removing the comma does not correct the error, but results in a run-on sentence (if not already one). There are several ways to correct a comma splice:
- Change the comma to a semicolon, em dash, or colon:
- It is nearly half past five; we cannot reach town before dark.
- It is nearly half past five—we cannot reach town before dark.
- We cannot reach town before dark: it is nearly half past five.
- In this example, the two clauses must be transposed. A colon often introduces a reason or explanation: the colon becomes a substitute for "because". The clause giving the reason ("it is nearly half past five") must follow the clause that needs explanation ("We cannot reach town before dark").
- Write the two clauses as two separate sentences:
- It is nearly half past five. We cannot reach town before dark.
- Insert a coordinating conjunction following the comma:
- It is nearly half past five, so we cannot reach town before dark.
- It is nearly half past five, and we cannot reach town before dark.
- Make one clause dependent on the other:
- Because it is nearly half past five, we cannot reach town before dark.
- It is nearly half past five, which means we cannot reach town before dark.
- Use a semicolon plus a conjunctive adverb:
- It is nearly half past five; hence, we cannot reach town before dark.
- Make the sentence a conditional statement:
- If it is nearly half past five, we cannot reach town before dark.
- Examples adapted from the online, public-domain 1918 edition of The Elements of Style.
- Truss, Lynne (2003). "That'll do, comma". Eats, Shoots & Leaves. London: Profile Books. ISBN 1-86197-612-7.
- Strunk, William, Jr. (1918). "Do not join independent clauses by a comma". The Elements of Style (1st ed.). Retrieved 2007-09-04.
- Buckley, Joanne. Checkmate: A Writing Reference for Canadians. Scarborough, Ontario: Nelson. 2003.
- "Run-on Sentences, Comma Splices". Retrieved 2008-01-24.
- Berry, Chris; Brizee, Allen (2006-08-31). "Run-ons – Comma Splices – Fused Sentences". Retrieved 2008-01-24.
- Hairston, Maxine; Ruszkiewicz, John J.; Friend, Christy (1998). "The Scott, Foresman Handbook for Writers" (5th ed.). New York: Longman: 509.
- Burchfield, R. W. (1996). Fowler, H. W., ed. Fowler's Modern English Usage (3rd ed.). Oxford: Oxford University Press. ISBN 0-19-869126-2.
- Alexander Jones, ed. (1966). Jerusalem Bible (Reader's Edition). Doubleday. ISBN 0-385-49918-3.
- The Elements of Style: full text of Strunk's 1918 edition