Fragments, Comma Splices & Fused Sentences

Sentence Fragments

A complete sentence must include a subject and a predicate. In a complete sentence, somebody or something (the subject) is doing something (the predicate, a verb). Both subject and predicate are necessary to form a complete thought. If you place a period at the end of a group of words which does not include both subject and predicate, you have made a sentence fragment or incomplete sentence. The following are all sentence fragments:

Giving away everything he owned. (Error)
His peculiar approach to solving problems. (Error)
Just in the nick of time. (Error)

"Giving away everything he owned" could be the subject of a sentence, as in "Giving away everything he owned made him feel great." ("Made" is the predicate.) But by itself, "Giving away everything he owned" has no predicate, does not form a complete thought, and cannot be punctuated as a sentence.

Sentence fragments often occur simply because the writer has separated elements in a sentence, usually dependent clauses, that should be left together.

Although he was disappointed by her behavior. He kept his mouth shut. Because he believed that complaining would only make the situation worse. (Errors)

Only "He kept his mouth shut" is a complete sentence. The other two items are dependent clauses, or fragments, not because they are missing something (both have a subject and predicate, making them clauses), but because they include a word ("although" and "because") which makes them dependent on a main, independent clause. They need to be connected to that main clause, as in the following:

Although he was disappointed by her behavior, he kept his mouth shut because he believed that complaining would only make the situation worse. (Correct)

Note that length has nothing to do with whether or not a sentence is complete.

It is. (Correct)

The above example is a complete sentence because it contains both subject and predicate. Something ("it") is doing something ("is"), even if what it is doing is merely existing.

Comma Splices

A comma splice occurs when two independent clauses (which could be sentences by themselves) are joined or spliced together with a comma but without the necessary connecting word, such as and, or, nor, for, but, yet and so. The following example is a comma splice:

The party was a total failure, we laughed about it all the way home. (Error)

Each half of this example, before and after the comma, is an independent clause and could be a complete sentence by itself. The example is a comma splice because these clauses have been jammed together with just a comma but without the necessary connecting word. To correct it, each clause could be written as a separate sentence:

The party was a total failure. We laughed about it all the way home. (Correct)

Of course, writing which contains many short sentences such as this can sound choppy and monotonous. The sentences may be better expressed as one sentence by using a connecting word.

The party was a total failure, and we laughed about it all the way home. (Correct)

Note that while the use of the comma in this situation is always correct, according to traditional rules, it is not always necessary. In contemporary English the comma is often omitted when joining two short independent clauses with a connecting word. Note also that a semicolon may be used instead of the comma and connecting word:

The party was a total failure; we laughed about it all the way home. (Correct)

Semicolons, however, should probably be used sparingly and usually for the purpose of emphasizing a cause/effect or other special relationship between the two clauses.

Although joining independent clauses with a connecting word is often better than writing many short, choppy sentences, it too can be overused and begin to sound repetitious.

The party was a total failure and we laughed about it all the way home and we never went back there again. (Awkward)

A better solution is to make one or more of the clauses dependent, using connecting words such as although, because, since, which, that, etc. In addition, the subject or predicate of a clause may often be dropped if it is clearly understood from other parts of the sentence.

Because the party was a total failure, we laughed about it all the way home and never went back there again. (Correct)

Sentences such as this not only sound better, in most situations, but they also emphasize the logical connections between the ideas in each part.

Fused Sentences

A fused sentence occurs when two independent clauses are run together without any connecting link.

The party was a total failure we laughed about it all the way home. (Error)

You might notice that a fused sentence is simply a comma splice without the comma. A fused sentence is fixed in exactly the same way as a comma splice.

One more time ...

NOT: He wanted very much to succeed, he worked late into the night.
And NOT: He wanted very much to succeed he worked late into the night.
But: He wanted very much to succeed, so he worked late into the night.
Or: Since he wanted very much to succeed, he worked late into the night.