This time we’ll take up the so-called “comma splice,” one of the most common errors in student writing. It is one form of the “run-on sentence,” but unlike a “fused” sentence, which runs together two independent clauses (i.e., complete sentences)—e.g., "The League of Nations was the centerpiece of President Wilson’s Fourteen Points the U.S. failure to ratify it devastated him"—the comma splice entails a comma between the two clauses, whereas what is required is a period or a semi-colon, that is, a full stop rather than just a pause.
Here’s an example: Julius Caesar crossed the Rubicon River in 49 BC, with this decision he launched Rome into a civil war.
Both clauses are independent and thus CANNOT be separated by a simple comma. Because, however, the two statements are closely related, it is tempting to signal merely a pause between them (using a comma) rather than a complete stop (signaled by the period).
To eliminate the error of a comma splice, but avoid the sharp halt broadcast by the period, you can employ one of two solutions: either place a semi-colon between the two statements (Julius Caesar crossed the Rubicon River in 49 BC; with this decision he launched Rome into a civil war.); or add a coordinating conjunction between them (Julius Caesar crossed the Rubicon River in 49 BC, and with this decision he launched Rome into a civil war.)
There are seven coordinating conjunctions, small words that allow you to use a comma between otherwise independent clauses. They are easy to remember with this acronym as a mnemonic device: fanboys (or, alternatively, boyfans): for, and, nor, but, or, yet, so.
Notice that “however” is not in the list. Proper use of this conjunctive adverb torments many students, so look for some illumination on that topic in a future column.