common mistake: comma splice

Run-on sentence: no punctuation or conjunction

A run-on sentence is a sentence in which two or more independent clauses (that is, complete sentences) are joined with no punctuation or conjunction. It is generally considered to be a grammatical error.

eg. It is nearly half past five we cannot reach town before dark.

A run-on sentence does not mean a sentence is too long; longer sentences are likely to be run-ons only when they contain more than one complete idea. A run-on sentence can be as short as four words—for instance: I drive she walks. In this case there are two complete ideas (independent clauses): two subjects paired with two (intransitive) verbs. So long as clauses are punctuated appropriately, a writer can assemble multiple independent clauses in a single sentence; in fact, a properly constructed sentence can be extended indefinitely.

Comma splice: a type of run-on sentence

A comma splice is the use of a comma to join ("splice") two independent clauses in a

sentence, where the clauses are not connected by a coordinating conjunction.

Some grammarians also include a comma splice, in which two independent clauses are joined with a comma, as a type of run-on sentence,[1] while others exclude comma splices from the definition of a run-on sentence.[2][3]

e.g. It is nearly half past five, we cannot reach town before dark.[1]

Comma splices are generally considered errors in both British and American English although they are acceptable in some languages, including French and German.

Comma splices are condemned in The Elements of Style, a popular American English style guide by E.B. White and William Strunk, Jr.[2]

According to Joanne Buckley,[3] writers often use conjunctive adverbs to separate two independent clauses instead of using a coordinating conjunction and, in doing so, create comma splices.

A coordinating conjunction is one of the following seven words: for, and, nor, but, or, yet, so. A conjunctive adverb, on the other hand, is a word like furthermore, however, moreover. However, 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.

Controversy about comma-splice

Grammarians disagree as to whether a comma splice also constitutes a run-on sentence. Some define run-on sentences to include comma splices,[4] but others limit the term to strictly mean those in which independent clauses are joined without any punctuation, thereby excluding comma splices.[5][6]

Strunk & White note 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.

Fowler[7] (third edition, 1996) notes a number of examples by reputable authors: “ 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: His word is a rock that strikes the ruthless, his sentences bring death to the wicked.[8]

Lynne Truss[9] 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."

Solution to comma-splice

Simply removing the comma does not correct the error, but results in a run-on sentence. There are several ways to correct this:

l           Change the comma to another punctuation mark:

It is nearly half past five; we cannot reach town before dark.

It is nearly half past five – we cannot reach town before dark.

l           Write the two clauses as two separate sentences:

It is nearly half past five. We cannot reach town before dark.

l           Insert a coordinating conjunction following the comma:

It is nearly half past five, and we cannot reach town before dark.

It is nearly half past five, so we cannot reach town before dark.

l           Make one clause dependent on the other:

As it is nearly half past five, we cannot reach town before dark.

Because it is nearly half past five, we cannot reach town before dark.

l           Use a semicolon or dash and a conjunctive adverb:

It is nearly half past five; therefore, we cannot reach town before dark.

It is nearly half past five – therefore, we cannot reach town before dark.