Here’s more about the comma, a topic of persistent difficulty to many writers. On more than one occasion lately, I’ve seen a curious decision made about where to place this troublesome mark of punctuation, and I thought an explanation might be in order when it comes to using a comma in conjunction with a conjunction. The question before us is whether placing a comma after the word but in the second sentence here is correct: I wasn’t able to get away for as long as I would have liked this summer. But, I did manage to take a couple of three-day weekends to relax.
Let’s begin with the basics. Conjunctions join grammatical elements and commas cut them apart. The term grammatical elements means single words or phrases or clauses, so the first step in checking whether we have put a comma in the best place is to be sure about just what it is we’re separating. In our example, the writer has placed the comma between the conjunction but and the clause it introduces, I did manage to take a couple of long weekends to relax. The word but is used to show a contrast of some sort, and my bet here would be that the writer decided a comma would emphasize the fact that despite not being able to get away for long, he still found it possible to relax over a few three-day weekends. He used the comma, in other words, to isolate the conjunction in order to strengthen its effect, even at the expense of detaching it from the clause it introduces.
Now that’s a problem, because we usually put a comma after an introductory conjunction when the conjunction is polysyllabic. If, for example, the writer had chosen the word however (another conjunction that shows contrast) instead of but, the comma would have been correct but the style clumsy: I wasn’t able to get away for as long as I would have liked this summer. However, I did manage to take a couple of three-day weekends to relax. This arrangement puts too much force into showing a contrast between two fairly simple ideas, a long vacation versus a few three-day weekends, and this inappropriate use of strength makes the second sentence top heavy, toppling the steady balance of the passage.
There is, though, an easier and better solution. If we remove the comma after but (with the intention not to isolate an already weak monosyllabic conjunction) and connect the two sentences into one statement, we produce a much smoother compound sentence whose moderate strength is appropriate to the ideas being communicated: I wasn’t able to get away for as long as I would have liked this summer, but I did manage to take a couple of three-day weekends to relax. A comma now appears before the conjunction but in order to separate the two clauses, not the conjunction from the clause it introduces. And the test to confirm that this is a better choice is naturalness. We can reasonably assume that the original passage was part of a casual conversation, and in that setting we would almost certainly not pause too long between the two statements, which is what the original period was meant to signify. That pause then necessitated (or so the writer thought) the comma after but in order to bring the two sentences back into opposing relation to each other.
Now all of this rightful explanation notwithstanding, when would a comma after but be correct? When it would be the first of a pair of commas: I wasn’t able to get away for as long as I would have liked this summer. But, even with gas prices as high as they are, I did manage to take a couple of three-day weekends to relax. Here, the comma after but is meant to isolate not the conjunction but the phrase even with gas prices as high as they are, and it does that in coordination with the second comma after are. The first comma, in other words, looks forward to the phrase, not backwards to the conjunction, and that makes all the difference.
The lesson, then? Always make sure first what grammatical element a comma is working with, and remember that determining that can sometimes mean looking outside a single sentence and sometimes deeper within it. We punctuate correctly when we take both precision and naturalness into consideration. A sharper eye and ear together will help us make the right choice.