Q: What has happened to the comma that joins parts of a compound sentence? Is it no longer used? I am seeing more and more compound sentences without it.
A: You don’t mention what kind of compound sentence you’re referring to, but we’ll do our best to answer your question.
There’s no absolute rule that one must use a comma to separate independent clauses joined by a conjunction. (A clause is a group of words with its own subject and verb.)
In a blog item last year, we noted that comma use is sometimes governed by taste and rhythm, not by any formal rule of punctuation.
One author may use a comma to separate parts of a compound sentence where another with somewhat different tastes in punctuation might leave the comma out.
In our Jan 23, 2009, blog item, we quoted a passage from John Updike’s Rabbit, Run as an example of the tasteful use and nonuse of commas.
In the passage (which we’ll repeat here), the protagonist, Rabbit Angstrom, shoots a basket on a playground as he’s watched by a group of schoolboys:
“As they stare hushed he sights squinting through blue clouds of weed smoke, a suddenly dark silhouette like a smokestack against the afternoon spring sky, setting his feet with care, wiggling the ball with nervousness in front of his chest, one widespread white hand on top of the ball and the other underneath, jiggling it patiently to get some adjustment in air itself. The cuticle moons on his fingernails are big. Then the ball seems to ride up the right lapel of his coat and comes off his shoulder as his knees dip down, and it appears the ball will miss because though he shot from an angle the ball is not going toward the backboard. It was not aimed there. It drops into the circle of the rim, whipping the net with a ladylike whisper.”
Updike uses (and doesn’t use) commas here because of a rhythmic effect he’s employing to build suspense. It would be a crime to interrupt and separate some of those breathless clauses.
Nonfiction is different, of course. But when no rules are being broken, writers have a lot of latitude in comma use.
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