Colon usage in English

Question

I have always thought that colons were used to clarify, expand, provide evidence for the preceding sentence, or show an example. I have heard that this is not true. (Truly, it is a shame if it is so: colons are my favorite punctuation.) Which of the following sentences uses the colon correctly:

There are three children in my class: two boys and one girl.

There are three children in my class: Jack, Larry, and Susan.

He is undoubtedly a true man: his beard is long and his hands are strong.

It was a big fireplace: not one of those ornamental dainties you find in the houses of snobs, but a real fireplace that had a utility surpassed only by the greatest furnaces.

She was a promiscuous fiend: she had seduced every guest who had dared to pass her threshold with her fiery eyes and her wealth.

This is the problem with your stubbornness: if you happen to be wrong, it will be all the more embarassing.

Never in my life have I been homesick: perhaps I am emotionally stronger than others, or perhaps they have a better home than I.

Answer 1

The Chicago Manual of Style, 14th Edition, section 5.97 agrees with you that a colon is used

to indicate a sequence in thought between two clauses that form a single sentence or to separate one clause from a second clause that contains an illustration or amplification of the first[.]

It also notes, however, that

In contemporary usage [...] such clauses are frequently separated by a semicolon [...] or are treated as separate sentences[.]

I personally would go for a semicolon in your 4th and 5th examples, and a full stop in the last, but the colon is certainly a viable choice.

(Section 5.99 also agrees with you that a colon is absolutely the correct punctuation to introduce an otherwise unadorned list as in your examples 1 and 2.)

Answer 2

What Hellion and Neil said—though I think the colons in your examples are absolutely fine and no worse than semicolons. I do agree with Hellion that the ones in your question itself might be better off replaced with a semicolon and a question mark, respectively.

Using a colon when the second clause is clearly a clarification etc. of the first is widely accepted. The fundamental problem is that it could be said that any sentence that follows another is quite often the continuation of a thought initiated earlier, and often provides further information connected with the sentence before it. Consider, as a random example, the second sentence of Neil's answer: it gives further (limiting) information about the statement made in the first sentence. Would it be worthy of a colon? I think it would not; but there is no definite line to be drawn between common and colon-deserving clarification.

If the first sentence seems evidently incomplete without the second one, if it seems to be begging for something, this might indicate that a colon would improve it. That would be the case if the reader, had there been a full stop, would have wondered, "huh, what is this supposed to mean?". A colon notifies the reader that he should not worry if he doesn't fully understand what he has just read: if he will just read on, all will be clear.

For your examples, it also matters what came before each sentence: could the reader have known what was meant by the first clause based on the preceding text or other context, or did he really need the second clause to stop wondering?

This is all rather abstract; I think everyone should decide for himself when circumstances are forcing enough for a colon. Too many colons can be tiring for the reader, because he is pressed on too often, allowed too few pauses to reflect. You may observe my natural usage of colons above, and see how you would use them differently.

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In addition, a colon can be used between two clauses in an opposition unmarked by words like but etc.

The contingents of the two countries had trouble cooperating, owing to their divergent views on the art of war. The Germans are fond of order: the French prefer bravado.

You could say that the French clause explains why the Germans clause is relevant and is hence nothing special; but I think regarding it as a separate use of the colon is somewhat more intuitive.

Answer 3

I'd say that all of the examples you give are generally within the bounds of normal use of the colon. Possibly in the last case I'd personally have a slight preference for a dash or just a full stop (on the grounds that the second utterance isn't actually a 'narrowing explanation' of the first), but I think a colon would also be common enough here.

Answer 4

I had read somewhere in my study of grammar that colons must be followed by complete sentences. This may have been over twenty years ago. However, this source seems to agree. You're also allowed to capitalize the first letter of the second sentence.

Your definition otherwise should be fine (the second sentence is meant to clarify the first).

If you desire to use an incomplete second sentence, you could try using an em dash, parentheses, or in some cases a comma, instead (commas can sometimes indicate a parenthetical phrase).

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According to the criteria outlined above, here is what I believe is correct and incorrect (noted in parentheses after each sentence).

"There are three children in my class: two boys and one girl." (Incorrect.)

"There are three children in my class: Jack, Larry, and Susan." (Incorrect.)

"He is undoubtedly a true man: his beard is long and his hands are strong." (Correct.)

"It was a big fireplace: not one of those ornamental dainties you find in the houses of snobs, but a real fireplace that had a utility surpassed only by the greatest furnaces." (Incorrect. There is no verb for the subject, which is the fireplace.)

"She was a promiscuous fiend: she had seduced every guest who had dared to pass her threshold with her fiery eyes and her wealth." (Correct.)

"This is the problem with your stubbornness: if you happen to be wrong, it will be all the more embarassing." (Correct.)

"Never in my life have I been homesick: perhaps I am emotionally stronger than others, or perhaps they have a better home than I." (Correct.)