I’ll bet I scared someone already with the last word in that title.

Let’s start at the beginning. This post came about because of a conversation on Twitter, begun by this tweet from Andy Bechtel (@andybechtel):

I’m not agreeing with that decision, either. Nor are many folks. But there are a few who don’t understand why it’s wrong. This post is for them. (Maybe it’s for you. I don’t know.)

So–appositives. What’s an appositive? It’s a grammatical structure in which two nouns or equivalents stand for the same thing. “This is my brother Bob.” Brother and Bob stand for the same person. “My first car, a Buick Century, burst into flames on the freeway.” My first car and a Buick Century stand for the same thing.

So what’s with the commas? There isn’t one in the first example, but there are two in the second.

The speaker in the first example has several brothers. We’re being introduced to the one named Bob. (Let’s say the others are Joe and Sam.)  If he had only one brother, we’d put a comma after “brother” to indicate that fact. (Mechanics are important, folks. They help us correctly understand what’s being presented to us.)

In the second example, the speaker (I’ll admit it, that’s my first car and that’s the fate it suffered) is talking about the first car they owned. There have been other cars afterward. The first one, though, was that Buick Century. Since there can be only one “first” of anything, there’s a comma setting off “a Buick Century” to show that it’s giving more information about that “first car.” If we removed that phrase from the sentence (commas indicate that we can pull out what’s set off by them), we still have a logical sentence. “My first car burst into flames on the freeway.”

Remember Bob? If he was the only brother, we’d put a comma after “brother” to indicate that fact. It’s consistent, this rule. (Not a guideline. A rule. There aren’t many, so those of you who like them should be happy at this point.) Then the statement “This is my brother” would be all the information we need. His name is a nice extra, but not required for understanding. If there are more brothers, though, we need his name to know which one we’re meeting. The name is required, so in that case it’s not set off with a comma.

Now, let’s look at the image in the tweet from Andy. During the Twitter conversation, he clarified that this is the first sentence in the essay. That makes a difference. We haven’t been told about this novel earlier in the piece. It’s the first mention. It’s not the only novel ever written, certainly, and it’s not the only novel ever written by Thomas Hardy (myself, I prefer The Mayor of Casterbridge). Because it’s not a unique entity, we need to indicate that to the readers. It’s THAT novel, not this one over here. We don’t use any commas on this first mention, just as we didn’t use any with brother Bob.

The way Andy’s son punctuated that sentence is correct. It’s that particular novel, which bears the title Tess of the d’Urbervilles. My brother Bob. The novel Tess of the d’Urbervilles. The film Gone with the Wind.

Now. IF (and this IF is important) the essay had begun differently, with a prior mention of the novel, we would set the title off with commas. Perhaps his son would have written:

Thomas Hardy was already a well-established novelist when The Graphic began publishing his most recent novel as a serial in 1891. That novel, Tess of the d’Urbervilles, has become a bane of AP English students in recent years.

NOW we need the commas, because the novel has already been introduced in a previous sentence. “His most recent novel” is the first mention. The second mention provides us with the title as an appositive (both “that novel” and the title refer to the same thing), and it’s set off with commas. We’re reading about one specific novel, which has already been mentioned; now we have more information about that same novel.

Feel free to ask questions in the comments or over on my Twitter feed. Writers need to understand the reasons behind mechanics. (So do editors, for that matter, but in my experience it’s the writers who ask the questions.)