My answer was: “It depends.” To her credit, she didn’t throw her manuscript at me. How you punctuate the sentence above depends on which style guide you use and the meaning of the sentence.
Let’s start with the basics. The word “Claire” in the example above is an appositive. An appositive is a noun or pronoun that explains, renames, or identifies another noun or pronoun in the sentence. Here’s an example: The piano, a spinet, was hard to move. “Spinet” is an appositive that further defines “piano.”
An appositive can be a word, phrase, or clause. Here’s an example of an appositive phrase: The piano, a spinet that a friend was selling, was hard to move. While appositives can appear at the beginning, middle, or end of the sentence, they most often come after the nouns they explain, rename, or identify.
Young women, their arms draped with leis, met the arriving tourists. (after the noun “women”)
Their arms draped with leis, young women met the arriving tourists. (beginning of the sentence)
Arriving at the airport, we saw the young women, their arms draped with leis. (end of the sentence)
Now comes the tougher part: how to properly punctuate an appositive. One rule, followed by many style guides and publications, says to use commas to separate appositives from the nouns they modify UNLESS the information in the appositive is necessary to understand the sentence. In this sentence, “the piano, a spinet, was hard to move,” the sentence would still make sense if you deleted the words “a spinet,” so the appositive is set off with commas.
However, if the appositive is necessary in order to understand the sentence, then you don’t need commas. In grammar guides, these words, phrases, or clauses that supply necessary information for sentence meaning may be called “restrictive appositives” or “restrictive clauses.”
Here’s an example: In high school, he developed an app that made him rich. If you remove “that made him rich,” the sentence doesn’t make as much sense. The appositive is necessary for the sentence’s meaning. One way to remember this rule is: Necessary information = no commas. Additional information = add commas.
The City of Falls Church, which is known for its fine public school system, is only 2.2 square miles. (additional information, add commas)
Shakespeare’s play Twelfth Night is a comedy. (necessary information, no commas)
Let’s return to my client’s example: My sister Claire planned the family reunion. Does the sentence need commas? It depends. (Stay with me here.) Some style guides, such as the Chicago Manual of Style apply the rule above and say it depends upon whether the appositive is necessary information. If there is more than one sister, then the word “Claire” is necessary because it defines which sister planned the reunion. Necessary information means no commas. On the other hand, if there’s only one sister, then you can remove her name, and the sentence still makes sense. Additional information means adding commas.
However, some publications make an exception to this rule. They don’t bother with commas if the appositive is just a name, whether the information is necessary for meaning or not.
My wife Joan is traveling for work this week.
She highly recommends her hairdresser Carlos.
His friend Paul will stop by today.
After considering all this, I told my client that her sentence about Claire didn’t need commas. That’s my position, and I’m sticking to it—no matter who throws what at me.