How is the comma being used in this sentence:

"But we are not principally concerned here with sentence construction, rather with finding out what makes a proper sentence so that we know where to put a full stop."

Can a writer attach any old fragment onto a main clause, separating it with a comma, of course, and call it a 'nonessential element'? How does one decide when to bracket words, phrases, or clauses from the rest of the sentence with commas?

closed as primarily opinion-based by curiousdannii, Hank, Cascabel, Chenmunka, tchrist Feb 16 '17 at 11:58

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.


The Chicago Manual of Style recommends this type of comma for separating two or more "complementary of antithetical" phrases or clauses (here "not principally" and "rather") referring to the same word (here "construction.")

The rules for commas are many and various and differ across style manuals, so your question about commas in general is far too broad for an adequate answer here.

  • It seems to me that the "rather" clause is referring to "concerned", not "construction". – Hot Licks Jan 15 '17 at 4:08
  • @HotLicks Sorry, but the statute has run on this one. – deadrat Jan 15 '17 at 5:22

Say the sentence aloud. Do you pause after "construction"? If so, you need the comma.

  • 1
    Did you mean to say, "Don't say the sentence aloud"? Punctuation is an artifact of written language, and the spoken word is a poor guide for using the marks. – deadrat Jan 15 '17 at 5:21
  • 1
    @deadrat - No, I meant what I said. Basic punctuation (periods, commas, question marks) is used to add the semantic clues that are present in spoken language to the written equivalent. – Hot Licks Jan 15 '17 at 13:43
  • Yes, I know you did. Mine was a rhetorical question meant to highlight a category error. Punctuation adds syntactic clues that allow readers to take the linear, unidirectional text of written language and reach the right parse of a tree-like, recursive, and back-referencing grammar. Most written language is not recited or intended to be recited, and indeed writing is available to those who can neither hear nor speak. Different speakers will agree on the grammar of some text but pronounce it differently, making speech a poor guide to punctuation usage. – deadrat Jan 15 '17 at 17:37

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