Comma Before But

By Maeve Maddox

This reader’s question illustrates the uncertainty felt by many writers about when to use a comma before the conjunction but:

In the following sentence, the secondary clause isn’t truly independent; it lacks a subject, yet it conveys an almost-complete thought: “I left Susan a message last week but haven’t heard back from her yet.” My question is whether a comma precedes but even though a subject doesn’t follow but. Put another way, is the secondary clause’s implied subject, I¸ sufficient to require a comma before the coordinating conjunction?

There is no “implied” subject in the sentence “I left Susan a message last week but haven’t heard back from her yet.” The sentence’s stated subject is I. It’s the subject of both verbs, the one before and the one after the but. The answer, therefore, is that no comma is needed before the but.

The rule for but is the same as that for the other six coordinating conjunctions: and, for, or, nor, so, and yet.

If the conjunction precedes an independent (main) clause, use a comma: “Jack tried a new diet, but he still gained weight.”

If the but is not followed by an independent clause, no comma is needed: “Jack tried a new diet but still gained weight.”

If a writer finds himself hesitating over a sentence like the one in the example, the easiest way to settle the comma question is to supply another subject for the second verb: “I left Susan a message last week, but I haven’t heard back from her yet.”

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21 Responses to “Comma Before But”

  • Jenxi

    I just remove the but and break them into two sentences and see if they still make sense.

    For example: “Jack tried a new diet, but he still gained weight.”
    You can split it into: “Jack tried a new diet.” “He still gained weight.”

    If the two parts are still proper sentences, then you need a comma. Otherwise, there should be no comma.

    For example: “Jack tried a new diet but still gained weight.”
    The second part is not a proper sentence: “Jack tried a new diet.” “Still gained weight.”

  • Elysia Brenner

    Hi, and thanks for your wonderful posts, as always! I have a question about this one…

    Would you say it is then *incorrect* to use a comma when the subject is not re-stated, or do you believe it is acceptable when chosen to create a pause (or for any other reason).

    Thanks!

  • Martha

    This brings up another question, which I haven’t fully resolved to my satisfaction. When your have an independent clause, with a comma before but (or and, for, nor, yet, etc.), and then you use an adverb such as nevertheless or however, which you would normally set off with commas, should you eliminate the comma after but? Or eliminate the commas setting off “nevertheless” or “however”?
    For example:
    The rider had a lot of experience, but, nevertheless, could not control the wild stallion.
    The skier had a lot of experience, and, furthermore, knew the mountain trails well.
    Should these sentences read:
    The rider had a lot of experience but, nevertheless, could not control the wild stallion.
    — or —
    The skier had a lot of experience, and furthermore knew the mountain trails well.
    Thanks for any insight.

  • Preciseedit

    I see this mistake often. A comma would separate the second verb, have heard, from the subject, I, which is a no-no.

  • Luiz Dorea

    Dear Maeve,

    It is the best (and the simplest) explanation over this subject I´ve ever seen.

    To the point!

    Cheers,

    Luiz

  • Richard Solomon

    Enjoy your tips.

    I’d like to see you address the comma and its use in compound sentences.

    So many people omit the comma in straightforward compound sentences with two distinct subjects and two distinct verbs.

    On the other hand, there are times when the comma seems unnecessary — especially when the clauses are short or the subject(s) are implied or understood.

    Eager to read more about it.

    Thanks!

  • Dale A. Wood

    To Richard Solomon: “On the other hand, there are times when the comma seems unnecessary — especially when the clauses are short.”
    Yes, when putting together two short sentences, the comma is not necessary. For example:
    1) The ship left the port and the crew scuttled her. (This happened to the German pocket battleship GRAF SPEE at Montevideo in 1939.)
    2) In a notable example sentence in an English textbook before 1960:
    “She took the pill and she went to bed.” My, my how the connotations of the language have changed with technology!
    D.A.W.

  • Preciseedit

    @ Elysian
    Yes, it’s incorrect. If you want to force a pause, use an em dash. With that said, in literary texts, you can break the rules for carefully considered reasons. Just know that you’re breaking the rules and make sure you are doing so purposely. In formal, technical, and academic texts, using a comma to create a pause is inappropriate.

    @ Richard
    In those cases, the comma might not be necessary for clarity. However, it is not wrong to use a comma there. I use the comma in those sentences
    1. to ensure clarity and
    2. to be consistent.

  • preciseedit

    @ Martha

    You asked a complex question, but I will take a crack at explaining how to use commas in your samples.

    Your sample: “The rider had a lot of experience, but, nevertheless, could not control the wild stallion.”

    FIRST, THE EASY PART: COMMA BEFORE CONJUNCTIONS

    This sentence should not have a comma before “but” because the text that follows is not an independent clause.

    If you were to remove “nevertheless,” the sentence would be structurally identical to the sentences described in this post, as follows:
    “The rider had a lot of experience but could not control the wild stallion.”
    It has no subject following “but” and, therefore, does not need a comma before “but” (similar to this sentence).

    In brief: If you have two independent clauses joined by a conjunction, use a comma before the conjunction.

    SECOND, THE HARD PART: COMMAS AROUND CONJUNCTIVE ADVERBS

    Now, let’s think about your question specifically and examine the commas around conjunctive adverbs, including “nevertheless.” Let’s add a subject to the second part of the sentence (which requires adding the comma before the conjunction) and see what happens.

    First approach: Some people say you should use commas because “nevertheless” and similar words are conjunctive adverbs, and conjunctive adverbs are set off from the rest of the sentence with commas. Using the commas around conjunctive adverbs following conjunctions can make a sentence sound choppy, but this advice represents strict adherence to comma rules.

    Following this advice gives you “The rider had a lot of experience, but, nevertheless, he could not control the wild stallion.”

    Second approach: Other people say you can omit the comma before the conjunctive adverb because it does not contribute to clarity. This advice represents a relaxation of comma rules and results in a smoother-sounding sentence.

    Following this advice gives you “The rider had a lot of experience, but nevertheless, he could not control the wild stallion.”

    As most of my writing is technical, I tend towards the first approach: use commas around the conjunctive adverb. If the sentence sounds choppy, rather than omitting the comma before the conjunctive adverb, I would revise the sentence to reduce the need for commas, such as by omitting the second subject.

    Here’s the point: The comma before the conjunction and the commas around conjunctive adverbs are separate issues. Adding commas (or not) around the conjunctive adverb does not affect the comma before the conjunction, and adding a comma before the conjunction does not affect the commas around the conjunctive adverb.

    For example, see my previous statement: “It has no subject following ‘but’ and, therefore, does not need a comma before ‘but.’ ”

    Here, we see the sentence does not need a comma before the conjunction “and” because the remaining text is not an independent clause. The text “therefore, does not need a comma before ‘but’ ” is not a complete sentence. However, this example still needs commas around the conjunctive adverb “therefore.”

    If we add a subject to the second part, we will use a comma before the conjunction, as noted in this post. We also still need the commas around the conjunctive adverb “therefore.” The result is as follows:
    “It has no subject following ‘but,’ and, therefore, it does not need a comma before “but.”

    SUMMARY

    To summarize, with examples:

    1. The rider had a lot of experience but could not control the wild stallion.
    (no second subject and no comma before the conjunction)

    2. The rider had a lot of experience, but he could not control the wild stallion.
    (second subject and comma before the conjunction)

    3. The rider had a lot of experience but, nevertheless, could not control the wild stallion.
    (no second subject and no comma before the conjunction, commas around the conjunctive adverb)

    4. The rider had a lot of experience, but, nevertheless, he could not control the wild stallion.
    (first approach, strict: second subject and comma before the conjunction, commas around the conjunctive adverb)

    5. The rider had a lot of experience, but nevertheless, he could not control the wild stallion.
    (second approach, relaxed: second subject and comma before the conjunction, comma only following the conjunctive adverb)

  • venqax

    @Preciseedit: Wow! Impressively and thoroughly done! I can never remember these kinds of things.

  • Maeve Maddox

    PreciseEdit is my punctuation hero.

  • Preciseedit

    /blush

  • venqax

    Actually the single most valuable sentence for me is:

    “…the easiest way to settle the comma question is to supply another subject for the second verb: “I left Susan a message last week, but I haven’t heard back from her yet.”

    I think I can remember, that.

  • Festus Abiatar

    Wow! That was a very nice explanation, @Preciseedit!

  • Martha

    Thank you so much for your clear and thoughtful answer to my question. Although I’ve tried before to find a credible answer to this problem, I couldn’t. I’m guessing it’s because of the problem of the strict versus relaxed rule of commas around conjunctive adverbs when there was also a required comma before a conjunction introducing an independent clause. I was able to find some answers but they were all over the map. You nailed the question and explained it perfectly. Thanks!

  • preciseedit

    @Martha: If you are confused by commas, you are in good company.

    Of the 100s of K – 12 teachers I have worked with over the years, only a small handful could explain how to use commas correctly. To no surprise, of the 100s of adult continuing education students I have taught over the years, most were confused by commas.

    I finally wrote Zen Comma because I, too, couldn’t find a comprehensive, clear, and credible resource dedicated to commas. The rules for commas make sense, but my experience suggests that people generally don’t understand the core principles of commas use and, therefore, have difficulty using them correctly.

    On the other hand, once a person fully understands the principles for commas, the rules will make sense. For example, consider the topic of Maeve’s post: commas with conjunctions before coordinating conjunctions. Following the principle that commas separate and identify individual meanings within sentences, we use a comma to separate individual independent clauses, and we leave out a comma to indicate that an idea is not yet complete.

    The following two correct examples show how this principle affects comma use.

    1. “I left Susan a message last week but haven’t heard back from her yet.”
    Here, we don’t use a comma before “but” because the second part must be connected to the first part for the sentence to be grammatically and conceptually correct. This sentence has a compound predicate (i.e., one subject with two verbs). A comma before “but” would separate the subject from its second verb, yet they must be connected to indicate a complete thought. However, by leaving out the comma, we indicate that the verb “have heard” is connected to the subject, which is in the first part of the sentence. Without a comma, the subject is correctly linked to its second predicate.

    2. “I left Susan a message last week, but I haven’t heard back from her yet.”
    Here, we use a comma to indicate that the second part is a separate thought. The comma indicates that one message is complete and that another is about to start.

    This same principle tells us that “I swam and she called for help” is incorrect, or, at least, doesn’t follow comma principles. The second half of the sentence is a separate thought and has its own subject and verb. With strict adherence to the principle, the correctly punctuated sentence is “I swam, and she called for help.” The comma tells the reader that the first idea is complete and that another is about to start.

    (People who follow a more relaxed application of the rules may leave out the comma in this sentence because it is short. However, consider whether a comma would help identify the two messages in this short sentence: “Dogs like running and jumping is good for them.” My advice regarding short compound sentences: If you use the comma sometimes for clarity, use it all the time for consistency.)

  • Preciseedit

    And for my final unsolicited comment…

    I created a graphic to demonstrate commas with compound predicates and independent clauses. You can see it here: http://zencomma.wordpress.com/2014/02/22/commas-before-and/

    (created with fond memories of “Conjunction Junction” from Grammar Rock)

  • venqax

    As I recall, grammar’s not your grandma, it’s your grammar.

    I bet I didn’t do those commas right.

  • Ernest Morariu

    @preciseedit, in your comment on February 22, 2014 2:15 pm you wrote “This same principle tells us that “I swam and she called for help” is incorrect, or, at least, doesn’t follow comma principles.”

    Is the comma before ‘or’ correct?

    Regards,
    Ernest

  • Dave

    Ernest Morariu, the comma before or seems correct because there is an implied “it” before “doesn’t follow comma principles.” There are two complete statements expresses.

  • R Atkins

    I prefer this solution:
    “The rider had a lot of experience; nevertheless, he could not control the wild stallion.”

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