comma before 'but' [compound predicate]: has a lot of info, but has

[SJF_Penguin]

I once had an English teacher who instructed students to always place a comma before the FANBOYS conjunctions regardless of whether an independent clause followed the conjunction. I've since realized that is not correct usage, but I often still debate about when to use a comma before but.

The Chicago Manual of Style has a lot of information about commas, but has no information about using them with but to show a contrast. In the sentence you just read, I placed a comma before but, but I'm not sure if it is correct. "Has no information about using them with but to show a contrast" is not an independent clause, so should I have omitted the comma? I'm the type of person who would prefer a solid rule as opposed to having to debate for ten minutes each time I write a sentence like this.

Also, I'm not sure if this is as strong a contrast, but should a comma be used in a sentence like this: "Jeff thought for a moment, but realized quickly that Tom's idea was likely their only hope"?

Thank you in advance for your thoughts and suggestions.

 

[Copyright]

For those unfamiliar with the term, FANBOYS conjunctions are For-And-Nor-But-Or-Yet-So.

 

[Parla]

The Chicago Manual of Style has a lot of information about commas, but has no information about using them with but to show a contrast. In the sentence you just read, I placed a comma before but, but I'm not sure if it is correct.

In my opinion, it's unnecessary and as an editor, I'd remove it; I wouldn't go so far as to label it "wrong". The reason I say that it's unnecessary is that the subject of the second "has" is the same as the subject of the first "has"; while some people might add a comma simply because of the distance between the two, there's no grammatical reason to do so. If a new subject were introduced, even if only a pronoun representing the Manual, a comma would be correct ("..., but it has no information about...").

 

[lb6067]

I had a comma before but in the following sentence, and now I am not so sure:

His parting words were of a man deeply in love, but a man broken and destroyed.