I came across this troubling sentence today:
“Wilson can find a solution to staffing problems, if a solution is possible.”
Take a look at that comma after problems. Should that comma be there?
Zen Comma Rule H says, “Don’t separate the descriptive clause or phrase if it occurs at the end of the sentence.” On the other hand, Rule W says, “Use commas to separate final descriptions that don’t refer to the immediately preceding text.” Which rule applies to the sentence?
The answer is Rule H. The comma is wrong. Now, let’s figure out why.
“If a solution is possible” describes the action “can find.” It establishes a condition for the action to occur, making it an adverbial descriptive phrase. (adverbial = modifies the action in some way) This role of the descriptive phrase is more apparent when we move it to the beginning of the sentence, as follows.
“If a solution is possible, Wilson can find a solution to staffing problems.”
Following Zen Comma Rule G, the descriptive phrase in the modified sentence is properly followed by a comma. The phrase is clearly describing the action “can find.” The comma serves two purposes here:
(1) indicate that the introductory description is finished and the main idea is about to start, and
(2) separate the introductory phrase from the subject that follows.
However, when we put the introductory phrase at the end of the sentence, neither purpose applies, so no comma is needed. Thus, the original sentence, with the descriptive phrase at the end, does not need the comma.
But why doesn’t comma Rule W apply? As we saw when re-ordering the sentence, the descriptive phrase “if a solution is possible” refers to “can find a solution to staffing problems.” With the descriptive phrase at the end of the sentence, it does refer to the immediately preceding text, and we don’t need the comma.
If the comma isn’t needed, why is it there? I have two answers to that question.
First, it may be an error. Maybe the writer does not know how to use commas well and made a mistake.
Second, it may be there to force a pause for dramatic effect. The writer may have added the comma to emphasize the descriptive phrase. A better way to do this is as follows:
“Wilson can find a solution to staffing problems—if a solution is possible.”
The comma is wrong, but it might serve a purpose, assuming that the writer intended this effect. To give the writer the benefit of my doubt, I will assume the writer added the comma for dramatic effect.