Writers may have been taught to add a comma to a sentence when it seems natural to have a pause. Such commas are rhetorical, meaning that they “show how words should be read aloud” but serve no grammatical function (Cook 109). Rhetorical commas are considered acceptable as long as they do not compromise clarity, group words inappropriately, or separate words that need to remain together. One common problem occurs when a single rhetorical comma is used to provide a pause between a subject and a verb. In the following example, the comma cuts off the subject (“participants”) from its verb (“were”):
Participants who refused to accept the notion that playing a pennywhistle could be a legitimate treatment for their ills, were more likely to be dismissed from the study.
To fix the issue, the comma can simply be removed. But the impulse to add a comma between subject and verb may indicate that the two elements are too far apart, in which case the sentence can be rewritten to bring them closer together:
Participants were more likely to be dismissed from the study if they refused to accept the notion that playing a pennywhistle could be a legitimate treatment for their ills.
Pausing after a Subject That Consists of a Series
A comma is sometimes inappropriately used between a subject that consists of a series of items and a verb:
Broccoli rabe, butternut squash, golden beets, and some of those locally sourced garlic scapes, would all be legitimate additions to the soup recipe.
The comma after “scapes,” used to indicate a pause (or perhaps because the writer is unsure how to punctuate a series of items), serves no grammatical purpose and should be removed, or the sentence should be rewritten:
Legitimate additions to the soup recipe would include broccoli rabe, butternut squash, golden beets, and some of those locally sourced garlic scapes.
Pausing in a Compound Predicate
A rhetorical comma can also inappropriately separate a verb in a compound predicate from its subject:
I ate two of those dark chocolates with the embossed design on them, and drank a glass of milk.
In this case, the comma separates the second verb (“drank”) from its subject (“I”) and should be removed.
If the subject is not clear from context alone, then a comma may be used to avoid misreading:
She called to the dog who barked at the snowman, and sat down.
The comma here signals that the verb “sat” takes “she” as its subject.
Rhetorical commas should be used with discretion and never when they break the structure of a sentence. As Claire Cook notes, “A single comma keeps words apart; it is harmful if the words it separates should interact” (122). For more guidance on commas, read our post on commas, conjunctions, and modifiers.
Cook, Claire Kehrwald. Line by Line: How to Edit Your Own Writing. Houghton Mifflin Harcourt, 1985.