Why are the answers for these two different?

  1. Wrong: It rained all day, and thus, the hut collapsed.

    Correct: It rained all day, and thus the hut collapsed.

    "And" with conjunctive adverbs: Add a comma before the coordinating conjunction but avoid inserting a comma after the conjunctive adverb.

  2. Wrong: I hate fish, however, I like chips.

    Correct: I hate fish; however, I like chips.

    Use a semicolon—not a comma—before a conjunctive adverb or transitional phrase (therefore, however, thus) that links two independent clauses.

  • 1
    Don't the explanations in parentheses do a good job of answering your question?
    – alphabet
    Oct 5, 2023 at 4:49
  • Your query is referring to the first puncutation mark in the corrected sentences; the answer is that 'thus' is not a coordinating conjunction, and 'and' is not a conjunctive adverb. Incidentally, It rained all day, and, thus, the hut collapsed and It rained all day, and thus the hut collapsed and It rained all day and, thus, the hut collapsed and It rained all day and thus the hut collapsed are all correct (whilst that first sentence is indeed wrong).
    – ryang
    Oct 5, 2023 at 6:49
  • @ryang << It rained all day, and, thus, the hut collapsed >> itself almost collapses under the weight of the commas. // While the sentence sounds rather unnatural anyway (and so it's hard to pick reasonable-sounding variants), the move towards minimal punctuation is gaining momentum and may well affect acceptability. And 'natural' (speech-reflecting) punctuation may some day license "It rained all day, and thus, the hut collapsed." Oct 5, 2023 at 11:40
  • @EdwinAshworth Yes, the first grey is very formal. // Regarding your final point about speaking that sentence: personally, if I don't pause before that 'thus' then I wouldn't pause after that 'thus' either.
    – ryang
    Oct 5, 2023 at 12:05
  • @ryang I can see contexts where I would pause there, contexts where I wouldn't (assuming I had to leave the words as is). There's a Dumbledore mini-speech where a pause is dramatically poignant ("It's a total secret ... and so, of course, the whole school knows about it.') Light parentheticals such as 'of course' may often take zero punctuation instead of commas (heavier punctuation such as brackets / ellipses available where warranted). Oct 5, 2023 at 13:16

1 Answer 1


The simple answer is that you normally use a comma (or no punctuation at all) before a conjunction, because we don't usually begin a clause with a conjunction -- it's used to connect phrases in a clause.

If you don't have a conjunction between the clauses, they should either be separate sentences or connected with a semicolon.

For instance, you can rewrite the first example without the "and" conjunction, and then you use a semicolon rather than comma.

It rained all day; thus, the hut collapsed.

  • As sentence fragments / starting a 'sentence' with a conjunction (ie a full stop before a conjunction) are nowadays accepted by many, a comma before a conjunction is becoming more acceptable. Oct 5, 2023 at 16:59
  • @EdwinAshworth Or not.
    – Barmar
    Oct 5, 2023 at 18:06
  • Well, I did qualify it with "normally". There are few hard and fast rules in English grammar, I'm sure you've pointed that out on numerous occasions.
    – Barmar
    Oct 5, 2023 at 19:22
  • 1
    I've updated the wording
    – Barmar
    Oct 6, 2023 at 13:19

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