Please note I am posting as a UK English writer, I point this out as I know there are differences between American and UK grammar guidelines or accepted practices. I would also add that I am asking from a novelist point of view rather than a technical writer.

Ignoring for now, introducing dialogue or lists, do I really need to worry about colons or can I use semicolons when a comma or period does not suit.

Are there any situations, within a sentence, where a colon is really the only recommended solution.

For example, in researching on the internet I came across the following example :-

A dolphin is not fish: it is a warm-blooded mammal.

It seems to me that a semicolon or comma would equally suffice. I am not asking for the correct formatting of this sentence, or for it to be corrected grammatically but rather more generally:-

Are then any such situations, with two independent clauses where a colon is an absolute must, or grammatically preferred over a semicolon, and regarded as better, writing practice.

Thank you

  • Hmmm. I think the example uses that colon to indicate the 2nd phrase 'supports' the 1st, but the context is a bit unclear…. 'A dolphin is not a fish: warm-blooded, no gills, tail is horizontal…' Here the part after the colon is a list of things that support the 1st statement. I think the example maybe does the same(?), but is easily interpreted as 2 separate observations (a compound sentence) –– I'm not sure how this is called, grammatically, but the sentence would also work in reverse as a list of things that support a conclusion. It's red, it came from an apple tree: it's an apple.
    – wetcircuit
    Commented Nov 18, 2021 at 17:11

2 Answers 2


Are then any such situations, with two independent clauses where a colon is an absolute must, or grammatically preferred over a semicolon, and regarded as better, writing practice.

If this is a question resolved by a style guide you adhere to then follow its guidance.

Otherwise, no. It's just about possible to write down the rules where English requires, or forbids, a full stop, exclamation mark or question mark. Wars have been started over how to wield the comma. But there is no consensus at all on semi-colons or colons.

Note that this answer addresses the issue of grammatically preferred and does not address stylistically preferred.

  • 'It's just about possible' - I think you mean 'It's just about impossible' - yea? :-) You say 'If this is a question resolved by a style guide you adhere to then follow its guidance.' I think this is good advice, the problem is I'm still finessing my style guide :-) So I will take your advice, finish deciding on my style and stick to it - good advice, thanks.
    – kerry
    Commented Nov 19, 2021 at 8:15
  • No, I meant what I wrote, it's just about possible. Commented Nov 19, 2021 at 9:00
  • My apologies - I get it now - thanks again
    – kerry
    Commented Nov 19, 2021 at 11:38

It is not simple but there is a difference between joining things with a colon or a semicolon.

With a colon there is an assumption of general to specific, or idea and explanation. For example, 'He had a stomach pain: it was constipation.'

With a semicolon there is an assumption of causation: it is as though the word 'because' has been substituted by the punctuation mark (though it is not that simple). Consider:

I entered. She left.

I entered; she left.

The first one says two unrelated events happened. The second one says she left because I entered.

What is the difference between the following sentences?

Henry is a good student: he always pays attention.
Henry is a good student; he always pays attention.

The first defines a good student as one who pays attention. The second says he is a good student because he pays attention. The difference is subtle but real.

Try these examples:

Our problem is simple: Mark made a mistake.
Our problem is simple; Mark made a mistake.

The first one means the problem is a mistake made by Mark. Maybe he ordered three coffees and there are four of them. The second is saying the difficulty is simple because of Mark’s mistake. Instead of it being a really complicated situation, like Mark said it was, it’s actually easily resolved. The two sentences are not the same.

Some people say you shouldn't use either colons or semicolons in fiction. My guess is they are people who don't know how to use them well. I think you should use every tool in your box. A carpenter uses a spokeshave when it is the best tool. Why shouldn't I use a colon?

  • your points are valid and I undesrtand, but I am going to play devil's advocate here. I think any (average) reader would read both examples as - 'Henry is a good student, he always pays attention.' and 'Our problem is simple, Mark made a mistake.' ie. 'Henry's a good student, bless him, he always pays attention.' and ' It was easy to see that Mark had made a mistake.' I think I would probably use a comma or maybe a semicolon if I wanted something more than a comma. I am not disagreeing with you but I think the subtlety would be lost on most. I'm thinking easiest for me :-)
    – kerry
    Commented Nov 19, 2021 at 8:11
  • I understand that subtlety can be lost. For example, people will read the same poem in many different ways. However, that doesn't mean I shouldn't try to make my meaning clear. Of course, if using a colon or semicolon obscures my meaning, I would leave it out. But I also assume that some of my readers would get what I'm doing. A farrier wouldn't not use a rasp just because the average person doesn't know what one is; I wouldn't not use a semicolon because a reader doesn't know what it is. Commented Nov 19, 2021 at 19:17

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