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Are the following sentences grammatically correct?

  1. Do you have any idea to prove it?
  2. Do you have any idea how to prove it?
  3. Do you have any idea about proving it?
apaderno
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3 Answers3

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The phrase do you have any idea can be roughly equivalent to can you think of any way:

We locked our keys in the car! Do you have any idea how we can get in?

or sometimes its used for emphasis in an emotional question:

You didn't come home until after 2 o'clock in the morning! Do you have any idea how worried we were?

So, more important than the grammatical correctness of your sentences, I think, is what are you trying to convey. Perhaps a team is trying to prove something that they believe is true, in which case I might say:

I'm convinced that's true; do you have any idea how we might prove it?

Or maybe we are asking a rhetorical question, and we are using those words for emphasis. In that case, I might say something more like:

Do you have any idea how hard that would be to prove?

If, on the other hand, we are unconvinced, and challenging someone's assertion about something, I think the do you have any idea construct would be an awkward fit. I'd probably say something more along the lines of:

I'm not so sure that's always the case - can you prove it?

If you're worried about being impolite with a question, you could turn it into a statement:

I think you might have trouble proving that.

J.R.
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    A perfect answer, with plenty of examples. A lot of people have suggested "can you prove it?" as a simpler alternative to the OP's constructs, but I think this sounds far more aggressive in most situations. JR's examples above offer some more neutral, context-sensitive alternatives (with *can you prove it* being used when challenging somebody else's assertion). – Emmabee Sep 10 '16 at 14:29
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In practice, competent native speakers would probably never produce #1 or #3. And whereas there's nothing actually "wrong" with #2, it's very much an informal idiomatic usage.

It would be completely inappropriate in a project progress report, for example, to say "The team don't have any idea when this project will be completed". Partly, obviously, because the team should know something like that, but mainly because to have no idea about [something] is far too informal. In OP's context, "Do you know how to prove it?" (or more succinctly, "Can you prove it?") are more suitable.

In informal (primarily spoken) contexts, [not] having an/any idea about something usually carries strong implications, similar to "I haven't a clue", or "Don't ask me!". For example...

"Do you have any idea how much that cost?"
would very often carry either or both the implications that the speaker believes (a) that the cost was [too] high, and (b) the other person should (but doesn't) know that. Correspondingly, the answer...

"I have no idea how much it cost"
often implies the speaker thinks it might have been expensive, but doesn't really care about the cost.

FumbleFingers
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  • by "idea" I mean the first meaning in http://oald8.oxfordlearnersdictionaries.com/dictionary/idea. A plan or a procedure of how to prove something that cannot be proved easily for example innocence of someone prisoned. –  Feb 06 '13 at 21:24
  • @CutieKrait: I knew what you meant by "idea". Note that it's irrelevant whether the thing you're asking for is a method of proving something difficult to establish conclusively, or of overcoming/dealing with some major problem ("Do you have any idea how to balance our budget?"). The implications I mentioned are often present, and the usage itself is invariably highly informal, even when it doesn't carry critical overtones. – FumbleFingers Feb 06 '13 at 22:07
  • 'In practice, competent native speakers would probably never produce #1 or #3.'

    Is #1 and #3 ungrammatical? Seems to me.

     – XPMai Feb 17 '21 at 07:11
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    @XPMai: I don't think there are any useful grammatical rules relevant to this general area. Many people would probably say that #1 and #3 are indeed "ungrammatical", but actually they're just *non-idiomatic* (they don't "break" any defined grammatical rules; they're just not things native Anglophones say). One very important point that I don't seem to have raised above concerns the fact that we have a strong preference for *singular* in negating / belittling contexts ("You have no idea how much I hate you!"), but plural for advice ("I have some ideas that might help"). – FumbleFingers Feb 17 '21 at 12:07
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Like @anderson commented, Use simple constructions when in doubt. Grammaticaly I see no problem in all the three sentences.

The first sentence is just another style of expressing the second sentence. Here how is implicit and in the second one how is explicit.

The third sentence is perfectly okay as well.

Mistu4u
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    How about replacing "idea" with "ideas"? –  Feb 06 '13 at 19:03
  • @CutieKrait, As far as I know, any one of them is correct i.e. using singular or plural. – Mistu4u Feb 06 '13 at 19:19
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    I had a different reaction on reading the first sentence; what I first thought (after thinking that some verb was missing) was not how to prove it, but whether one was even going to try. Or, to paraphrase, "Do you have any thought that you might want to try to prove it?" After reading the other two sentences, I realized that isn't what was meant, but if I read, or heard, the first sentence in isolation, I'm quite certain I would misunderstand. So, even if it's strictly grammatical, it isn't clear. – barbara beeton Feb 06 '13 at 20:20
  • I don't know, but frankly even before glancing on the second sentence I took how to be implicit there.@barbarabeeton, however if you say so, it might be different people interpret it in different ways! – Mistu4u Feb 06 '13 at 20:24