I'm a non-native speaker. When I was a student of English my teachers mentioned this answer was to be avoided in formal situations, except for its literal meaning. Years later I heard it twice, as a reply to questions, in formal lectures at my professional congresses. What I want to know is whether it is proper to answer that way, when you me an "I don't know" or "I have no idea", in formal spoken or written English.

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    There is what can be said, what should be said, what was said, and what was heard. When you, OP, ask such questions, my question to you is "acceptable to whom?" Who is the audience? What level of acceptance would properly answer your question? On target: Is the statement grammatically correct? Yes. Is the statement understood by an audience in grammar, content, and context? Yes. Is the statement allowed to be stated as such? Yes. Given this, what do you want to know?
    – SrJoven
    Oct 6, 2014 at 2:36
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    It may sound a bit informal, but the usage is correct. Now, when you say "formal", I imagine you're talking about high-collar, CEO level or maybe even Royal Family formal, at which point it's less about being rude and more not making yourself look like an unreliable man (that is, you want to avoid "I don't know" and its variations entirely)
    – Raestloz
    Oct 6, 2014 at 3:20
  • ODO: have a clue [usually with negative] informal Know about something or about how to do something: I didn’t have a clue what was happening (oxforddictionaries.com/definition/english/clue) Note the usage note I've emphasized above: informal HTH.
    – Kris
    Oct 6, 2014 at 6:06
  • @Kris Then, the implied question here is kinda why is it being used in a lecture? The OP obviously understands that it's considered informal - that's the reason they're asking the question! Oct 6, 2014 at 12:39
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    The problem with answering your question is in the response to "who's the audience" In general, the statement is not formal. It doesn't mean it's not something people say, though. As mentioned in the comments, the expression as written, or similar "I don't know", is not one that would be expected in formal writing. That is to say, while it may be found in formal writing, it would be expected that another euphemism would be used, such as "cannot be determined", unless quoting someone.
    – SrJoven
    Oct 6, 2014 at 14:29

2 Answers 2


The Chief of Detectives in a major city's police force is at a press conference, reporting on progress solving several mysterious disappearances of prominent people. Minutes earlier, the CoD and his detectives have bemoaned among themselves that they don't have a clue. According to your English teacher, the CoD can say, in the press conference, that he doesn't have a clue. But does he say that? Of course not!

A person whose opinion counts for something can use the phrase "don't have a clue" only when it is safe -- for example, when she is among peers who are also friends, none of whom are likely to stab her in the back later.

As for the International Congress where you heard the phrase: if it was in a formal presentation, I'll bet that it was about an aspect of the subject in which everyone would agree that no one had a clue or it was a dismissive answer to a question the answerer regarded as stupid.

MDs should be especially wary of using the phrase if a hypochondriac could be anywhere within earshot.

In situations where nothing is at stake, "I don't have a clue" is OK. Such situations are unlikely to be formal.

  • It took me a year to see a decent answer here. Thank you.
    – Centaurus
    Dec 4, 2015 at 0:51

In most spoken language, as you've noticed, it will be quite acceptable, except probably in technical settings. However for written language, it's only really acceptable in informal situations.

For example, in a story, a tweet, or blog post, no matter the audience, it would be acceptable, but in a formal letter, technical paper, or legal document it would not be acceptable.

  • The defendant responded 'I don't have a clue!' Sorry, 'I don't know!' Oct 6, 2014 at 8:20

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