Have no idea is a phrase appears many times in the book We have no idea: A guide to the unknown universe, for example in the title, or in this sentence:

It's the biggest chunk of reality, and we almost have no idea what it is

My question is: What does the phrase "have no idea" mean? Can we understand it literally that people haven't got any idea about something or it means that people don't know about something?

I know that it's quite confusing and may be trivial question, but I'm translate from English to my native language, so I have to find the most exact words to describe that phrase, so please help me.


  • I don't think the expression is peculiar to English. In Hungarian the phrase "fogalmam since" (literally "I have no idea") is used in much the same way.
    – bof
    Jan 23, 2018 at 5:40
  • 1
    It's an emphatic way of saying, 'I do not know anything about this'. Whose dog is it tore up your front garden ? I have no idea. It can be used as a way of dissociating oneself from any involvement or any responsibility.
    – Nigel J
    Jan 23, 2018 at 6:24
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    What's confusing? The universe, your interpretation of its meaning, or your question? (I'm just kidding) I have almost no idea what you're trying to ask... would be true if I didn't have an idea what the idiom meant but I do have some idea. It's just another way of saying "I haven't a clue" :)))
    – Mari-Lou A
    Jan 23, 2018 at 7:25

2 Answers 2


It's not strictly literal, the subject may in fact have some ideas. To "have no idea" means that whatever ideas the subject does have, if any, are either highly uncertain (usually, when the speaker is the subject) or presumed to be incorrect (usually, when the subject is someone else).

If I say "I/we have no idea", I mean that I am / we are highly unsure, though I probably have at least some vague thoughts on the matter. If I say "he has no idea", I mean that I think he is either ignorant or wrong.

  • 1
    I disagree with your added note that I/we "probably have at least some vague thoughts on the matter." The phrase "I have no idea" means "I don't know" and does not implicate even the vaguest notion. To the contrary, it's synonymous with (the somewhat old-fashioned), "I haven't the vaguest notion" or "I haven't the slightest clue"/"I don't have a clue."
    – Iolite_Jay
    Mar 8, 2018 at 6:01
  • @lolite_Jay I agree completely that "no idea" does not imply any idea in the slightest. I thought it was worth pointing out, though, that it certainly doesn't rule it out, and many people use it to convey a looser sense of ignorance, e.g. someone who "has no idea" what their spouse has planned for a special weekend away would not be telling a lie if they did, in fact, have some pretty strong hunches.
    – Lemma
    Mar 9, 2018 at 8:10
  • I find that to be an inappropriate use for "no idea," actually. Having no idea/clue means having had no inkling of it at all, so one could only use the phrase ironically (and in fact we often do, in precisely those situations: "REA-uh-lly? I had NOooo idea!" with dramatic eyeroll). If you had a hunch, you'd say you had a hunch, or suspected. The only exception: "I noticed X and Y, but I had no idea they were actually serious about it!" (here the predicted outcome was too far-out to take seriously, so it's the spouse's "real plans/intentions" that eluded understanding).
    – Iolite_Jay
    Apr 10, 2018 at 5:09

To "have no idea" expresses that you don't have enough information to make a definite statement about something. So one could in fact have some feeling or suspect but still not feel confident enough in the facts to state your opinion.

  • 1
    Surely that's 'have only vague ideas about ...'? Dec 4, 2020 at 12:54

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