(A Twitter friend pointed out that a serial comma can cause confusion. This post is in response. In this post, I show that the serial comma doesn’t cause the confusion but that the overall sentence structure causes the confusion. By fixing the sentence structure, I solve the problem.)
Commas are necessary for helping the reader understand your writing. They separate elements within sentences that each have a unique meaning. With commas in correct places, the reader, then, can identify each part of a sentence that has s separate meaning and can make sense of the whole sentence.
But correct commas use can also lead to confusion in one particular instance. Consider this sentence:
Nancy gave the medicine to Tom, her brother, and her daughter.
The commas are correct in this sample, but they create a problem. Did Nancy give the medicine to (a) Tom, and (b) her brother, and (c) her daughter, meaning did she give the medicine to 3 people? Or did she give the medicine to only 2 people: Tom (assuming that Tom is her brother) and her daughter?
The problem is that we don’t know whether Tom is her brother or whether Tom and her brother are two different people.
If I had written “Nancy gave the medicine to Tom, her brother,” then the sentence would clearly indicate that Tom and her brother are the same person. Here, her brother is an appositive for Tom, indicating that her brother is simply another way of saying Tom. In the sample, however, we have a series of three with and following her brother, so the reader can’t be sure that her brother is Tom. In short, the sample is confusing.
But we can solve this confusion by fixing the sentence structure.
If Nancy gave the medicine to two people (with Tom and her brother being the same person), we can clarify the sentence as follows.
Nancy gave the medicine to her brother, named Tom, and her daughter. (This explicitly states that that Tom and her brother are the same person. Strategy 1: Tell the reader what you mean.)
Nancy gave the medicine to Tom, her brother, and to her daughter. (By repeating to, this sentence does not have a series three, indicating that Nancy gave the medicine to two people. Strategy 2: Revise so you no longer have a potential series of 3.)
If Nancy gave the medicine to three people (with Tom and her brother being different people), we can clarify the sentence as follows.
Nancy gave the medicine to her daughter, her brother, and Tom. (Her daughter and her brother must be different people, and and before Tom indicates that he is also a different person, thus indicating three people. Strategy 3: Reorder the names.)
Here’s the bottom line: When you have names in a series, think about the different ways the reader may interpret the sentence. If more than one interpretation is possible, revise the sentence to ensure that the reader will interpret it correctly. Use commas correctly (of course), but make sure they add clarity, not confusion.
Need help with commas? Get Zen Comma, an instructive reference guide on the 17 major uses and misuses of commas, available in PDF and Kindle formats. Read more about Zen Comma.