I've often thought that commas should be placed in pairs, in sentences.
Then why didn't you do so in that one?
Answer: because it only needs one. But this sentence is a little awkward. Better to rearrange it: I've often thought that, in a sentence, commas should be paired. You end up with a pair of commas, but that's just a coincidence. Next time you may have one or three. Obviously that rule is bogus!
Bob, after thinking things over, decided to go to the store. << this would be correct usage of commas, correct?
Yes. But this sentence can be rearranged in two different ways, changing the number of commas required.
After thinking things over, Bob decided to go to the store. (One comma)
Bob decided to go to the store after thinking things over. (Zero commas) Note that this construction does not make it clear whether it was the decision that took place after the thinking, or the trip to the store. But since that ambiguity is unimportant, there's no harm.
My question is...is this correct or incorrect: But, Bob was right. << does that sentence NOT need a comma at all?
If you're writing dialog in a story or a novel (in which case the sentence would be enclosed in quotation marks) the comma would represent a slight pause in colloquial speech. If there's no comma, it means that the character didn't pause there. It's the difference between Bob using "but" as a synonym for "however" (which requires the comma--and is crappy grammar so you'd be careful which character's mouth you put it in, certainly not the philosophy professor), and Bob simply speaking a sentence fragment, perhaps the second half of a sentence which was rudely interrupted by another character (which takes no comma, although you might choose to end the first half of the sentence with an ellipsis and begin the second half the same way, to help the reader navigate through this complicated dialog).
But if this is your own writing for a class, a letter to the editor, or anything loftier than an internet discussion board, you should know that it's frowned on to begin a written sentence with a conjunction; "however" (an adverb) is more appropriate. And as I noted, never use "but" as a synonym for "however" in serious writing; it's just plain wrong.
And further...how about this sentence? -- Bob bought oranges, bananas, strawberries, and wine at the store. -- Would there be no comma after strawberries in this sentence?
That is called the
serial comma and grammarians joke that it generates as much controversy as a
serial killer. It's amusing to note that Americans call it the "Oxford comma," insisting that it's a stuffy formality used in the U.K., against which we Americans must be as vigilant as the British spelling of "centre" and "colour"... while the British call it the "Harvard comma" and blame it on us!
In fact, it goes in and out of vogue every couple of generations. When I was in grade school in the 1940s and 50s, the serial comma had been considered proper for quite some time, and Americans were starting to get tired of it. So new textbooks taught us not to use it. Today, it's well-established in American stylebooks that the serial comma must never be used. Remember that stylebooks are written by and for journalists, and every millimeter of space they can squeeze out of an article is one more millimeter that can be sold for advertising. These are the same people who tried to convince us that it was correct to write "Mr. Jones' hat" thirty years ago, but we successfully resisted that atrocity.
So no, don't use the serial comma.
Finally: Susan, Bob's sister, didn't want to go to the store, afterall. -- Is a comma necessary after 'store?'
Before we get into that, allow me to be the first to break the news to you that
there is no such word as "afterall." It is "after all," regardless of how you're using it. Back on topic, no, I would not put a comma between "store" and "after." If you're writing dialog and you want to show the reader that the character speaking that sentence put a pause between the two words, then just use an ellipsis: that's what it's for.
Susan didn't want to go to the store... after all.
The speaker appears to be a bit disgusted that Susan has changed her mind for the fourth or fifth time. If she only changed it once, well hey, that's what "after all"
means!
It's one of those pet peeves that I run across from time to time, and I wonder...sheesh, what is the RIGHT way to use commas?
The comma was invented to render a
pause in spoken language
visible in written language. So just start there. Forget the "rule" about commas having to be paired. They don't, and I can't imagine who told you that!
If necessary, speak your sentence out loud two or three times and notice where you pause. Then write it that way.
That said, common sense can overturn any rule. The following example is surely apocryphal since no one I know has ever found the source, but it's a great example anyway.
The author of a book is said to have inscribed the dedication:
"To my parents, Ayn Rand and God."
The serial comma would certainly have been appropriate in this case.
