You've probably heard of comma splices; they are a
common error. Do you know what they are and how
you can avoid them? It's time to learn!
What is a Comma Splice?
A comma splice occurs when you use a comma to join two
complete sentences without placing an appropriate joining
word between them. The comma just isn't strong enough to
do the job of making one grammatical sentence out of two.
Learn to recognize what comma splices look like, and be sure
to avoid them in your essays.
Here is a simple example of a comma splice:
I completed my essay, I have not submitted it.
A closely related grammatical error is the run-on sentence. It
occurs when you join two complete sentences without any
punctuation mark at all:
I completed my essay I have not submitted it.
Fixing a run-on sentence is no different from fixing a comma
Some Basic Definitions
The grammatical term for a group of words that can stand on its own
as a complete sentence is independent clause. To be an independent
clause, the group of words must contain both a subject and a verb. In
the independent clause I completed my essay, I is the subject, and
completed is the verb.
The grammatical term for a joining word is conjunction. Conjunctions
refer to those words in the English language such as and or but or since
or because that allow us to build more complex sentences out of
simpler ones. The conjunctions and and but are called coordinating
conjunctions; the conjunctions since and because are called
It is not essential to remember these grammatical terms, though they
can be useful for conveying important points about grammar. What
really matters is to know comma splices when you see them and to be
familiar with the various ways of fixing them.
How to Fix a Comma Splice
Here are four straightforward ways to solve the
comma splice problem. Understand the subtle
differences between them, and make sure you
don't get into the habit of always solving your
comma splice problems in the same way. Look at
each comma splice in your writing as an
opportunity to gain mastery over the tools for
building complex sentences out of simpler ones.
Solution 1: Use a period.
The simplest way to fix a comma splice is to separate the two improperly
joined sentences. Simply replace the comma with a period. The two
sentences may sound a bit abrupt placed one after the other, but at least
they will be grammatical:
I completed my essay. I have not submitted it.
A period may be your best choice for fixing a comma splice when any of the
following conditions holds: (1) the logical connection between the two
independent clauses is self-evident; (2) one or both of the clauses is long;
or (3) the ideas represented in the two clauses are distinct.
I completed my English essay. Now I must go to the library and
begin research at once on my fifteen-page History term paper.
Solution 2: Use a semi-colon.
If you want a simple solution to the comma splice, but you prefer to
encapsulate your two ideas in one sentence rather than two, then use a semicolon rather than a period:
I completed my essay; I have not submitted it.
A semi-colon is probably the most appropriate remedy for your comma splice
when the following two conditions hold: (1) the logical connection between the
two independent clauses is already clear, and (2) the ideas represented in the
two clauses are very closely related. In particular, when the relation between
the two clauses is one of sequence-either a sequence in time or a logical
sequence-then a semi-colon is just what you need:
I completed my English essay; next I will tackle my History essay.
Solution 3: Use a coordinating conjunction.
Like the semi-colon, a conjunction allows you to combine your two ideas in a
single sentence. But it has the added advantage of allowing you to indicate
the logical relationship between the two ideas. In our comma splice
example, the relationship is one of contrast: I completed the essay, but I
haven't submitted it even though that would have been the expected thing
The coordinating conjunction but compactly conveys this sense of the
unexpected or contradictory:
I completed my essay, but I have not submitted it.
In all, there are seven coordinating conjunctions:
for, and, nor, but, or, yet, so
They cover the most basic kinds of logical relationships
that can exist between two separate ideas.
Solution 4: Use a subordinating conjunction.
Subordinating conjunctions are similar to coordinating conjunctions in
that they allow you to indicate the logical relationship between two
independent clauses. However, unlike coordinating conjunctions,
subordinating conjunctions lay unequal stress on the two parts of the
new sentence. We can use the subordinating conjunction although to
solve our comma splice problem, and we can do so in two distinct ways
I completed my essay, although I have not submitted it.
Although I completed my essay, I have not submitted it.
As the word subordinating suggests, we place less stress on the clause
introduced by the subordinating conjunction. In the first example, the fact
that I have not submitted the essay appears as an afterthought; in the
second example, it is the point.
There are a great many subordinating conjunctions in the English
language. Here are a few of the more common ones:
while, although, because, if, since, unless, whether, when, why, as,
before, after, if, whether, that, once
Complete List of Conjunctions
How Not to Fix a Comma Splice
Never try to join two sentences with a comma followed by a conjunctive
adverb. The most common form of this error involves joining two sentences
with the word however:
I completed my essay, however I have not submitted it.
This sentence is still a comma splice. Learn to distinguish conjunctive
adverbs from subordinating conjunctions; they do not function in the same
way. Conjunctive adverbs should be used to begin independent clauses, not
to join them.
Here is just a small sample of the many conjunctive adverbs that are
available to you. Notice that conjunctive adverbs can consist of phrases as
well as single words:
however, nevertheless, furthermore, moreover, hence, therefore,
similarly, certainly, by contrast, in other words, in addition
Note that you can use a conjunctive adverb to help fix a comma splice, but
you must remember to put a period or a semi-colon in front of the second
I completed my essay. However, I have not submitted it.
I completed my essay; however, I have not submitted it.
A conjunctive adverb like however usually makes for a more formal and more
emphatic transition between clauses than the more casual conjunctions but
and although. If you rely too heavily on conjunctive adverbs, your writing will
begin to sound stiff. Save your howevers for when you really need them: (1) for
emphasizing the key turns in your argument, or (2) for signaling a contrast
between long, complex sentences. Many stylists prefer not to use however
right at the beginning of a sentence.
I completed my essay in just one draft, a process that took me only
three hours. This last essay, however, was a mere two pages long, and
I have learned the hard way that neglecting to revise my papers
inevitably results in a weaker paper and a lower grade.
Examples & Corrections
Learn to recognize the types of constructions
that cause comma splices. For example, many
students incorrectly splice together sentences
when a transitional word or phrase introduces
the second sentence. The examples following
illustrate common causes of comma splices and
how to correct them.
COMMA SPLICE: This has been a very dry summer, therefore, the
supply of water in the reservoirs is low.
EXPLANATION: The comma after summer (before the transitional
word therefore) is too weak. (We don't know whether
therefore belongs to the clause before it or the one after it.)
WAYS TO CORRECT: Use a semicolon to correct the comma splice:
This has been a very dry summer; therefore, the supply of water
in the reservoirs is low. (The comma after therefore stays there.)
Rephrase, using a coordinating conjunction: This has been as
very dry summer, so the supply of water in the reservoirs is low.
Make it two sentences: This has been a very dry summer.
Therefore, the supply of water in the reservoirs is low. Make the
first sentence a subordinate clause: Because this has been a very
dry summer, the supply of water in the reservoirs is low.
COMMA SPLICE: Heavy rain fell throughout the night, by
morning every major road was flooded.
EXPLANATION: Although the second statement is a
continuation of the idea, the two statements are
grammatically independent sentences.
WAYS TO CORRECT: Make two sentences: Heavy rain fell
throughout the night. By morning every major road was
flooded. Use a coordinating conjunction: Heavy rain fell
throughout the night, and by morning every major road was
flooded. Make a subordinate clause out of the first sentence:
Because heavy rain fell throughout the night, every major road
was flooded in the morning.
COMMA SPLICE: Mary kissed Frank, then, for no apparent
reason, she slapped him.
EXPLANATION: Again, although the sentences describe a
continuous action, they are nonetheless two distinct
sentences. The break should be between Frank and then.
WAYS TO CORRECT: Use a semicolon: Mary kissed Frank; then, for no
apparent reason, she slapped him. Use two sentences: Mary
kissed Frank. Then, for no apparent reason, she slapped him. Use
a coordinating conjunction: Mary kissed Frank, and then, for no
apparent reason, she slapped him. (The words for no apparent
reason constitute a parenthetical phrase or "interrupter," which is
set off by commas regardless of the punctuation or structure of
the rest of the sentence.)
COMMA SPLICE: John studied hard for the test, he failed it
EXPLANATION: Two related (contrasting) sentences are
incorrectly connected with only a comma.
WAYS TO CORRECT: Insert a coordinating conjunction: John
studied hard for the test, but he failed it anyway. Subordinate
one of the clauses: Although John studied hard for the test, he
failed it anyway. Use a semicolon: John studied hard for the
test; he failed it anyway.
COMMA SPLICE: Charlie is not only handsome, he is also rich.
EXPLANATION: Despite the use of "not only . . . also," this
construction consists of two grammatically independent
WAYS TO CORRECT: Add a coordinating conjunction (i.e., balance not
only with but also): Charlie is not only handsome, but he is also
rich. Compress the idea: Charlie is not only handsome but rich. Use
a semicolon: Charlie is not only handsome; he is also rich.