Welcome to “Notes from the Proofreader”: a semimonthly discussion of grammar, usage, and punctuation pitfalls. In this post, we’ll be discussing the pesky comma splice (aka the run-on sentence).
The comma is a useful little piece of punctuation. Among it’s many jobs, it can separate coordinate adjectives and items in a series. It can also set off elements: introductory phrases, parenthetical information, nonrestrictive clauses and phrases, names used in direct address, etc. The 16th edition of The Chicago Manual of Style 6.16–6.53 offers a more comprehensive list of its uses.
What a comma cannot do is hold together independent clauses all by itself.* It’s just not strong enough. The comma requires the help of a conjunction to successfully join them. Or it can be replaced by a stronger piece of punctuation. Or the offending splice can be revised so that there’s only one independent clause.
Let’s make sure we don’t give the comma more than it can handle.
*Except in “those rare case when one has a trio of short independent clauses that all have the same grammatical subject: He came, he saw, he conquered.” (Amy Einsohn. The Copyeditor’s Handbook, 2nd Ed. [University of California Press, 2006], 80)