I think I've seen someone used "who knows" not in a separate sentence. Let me first explain what I'm not looking for:

Someday our little Donald might become our president. Who knows?

This is a typical example I find in those "English for learners" websites. Here "who knows" is used in a separate sentence. But I wonder if there are ways to use it in a part of a single sentence, such as "Who knows somebody does something." And if that is allowed, what sort of relative clauses can follow "who knows"?

If such usages are common, it would be great if you could point me to a few examples online. I've found this but not many others:

It's never an easy decision: Should I interview someone who wants to talk in public, but who knows that a word out of line could mean arrest and imprisonment?

Incidentally, does the BBC writer imply a word can likely to lead to arrest and imprisonment here?

  • Idiomatically we just don't use Who knows? the way you're thinking. Your final example is almost certainly from a non-native speaker, because the normal form there would be, for example, ... but who would have thought that a word out of line could mean arrest and imprisonment? Apr 12, 2016 at 15:35
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    @FumbleFingers I think the context of the question throws off your reading of the final example (it did for me at first as well). I believe the sentence is talking about someone who wants to talk, but knows it isn't a good idea. But reading "who knows?" with the inflection of a question so many times before reading the example makes you read "who" as a question instead of a relative pronoun.
    – Sarah
    Apr 12, 2016 at 15:44
  • @Sarah: I didn't spend a lot of time thinking about what that final example might be intended to mean. It simply didn't look like anything a native speaker would say, given the earlier stuff about Who knows? On looking again I see it's normal English, but nothing to do with OP's title or rhetorical questions. Whatever - I'll leave the comment there, otherwise yours wouldn't make sense. Apr 12, 2016 at 16:25
  • @FumbleFingers exactly my point. The whole question primes you to read it as a rhetorical question (which doesn't seem natural/make much sense), but stepping back and reading it neutrally it is perfectly natural, just not as a rhetorical question.
    – Sarah
    Apr 12, 2016 at 16:41
  • @Sarah: I didn't notice until after my second comment that you'd actually explained things in an Answer (since upvoted). But clearly we were both susceptible to the misreading because of the way the question is framed (even though only you took the trouble to think it through), so it may actually be an advantage for OP or others to see how easy it is to be misled if you just consider two consecutive words in isolation, without regard to their syntactic role in the complete utterance. Apr 12, 2016 at 16:49

1 Answer 1


Your BBC sentence is using "who knows" in a totally different way than the premise of your question.

In "Someday our little Donald might become our president. Who knows?", the "who knows?" part is like saying "nobody can know".

You could use this same meaning of the phrase in a sentence like "Who knows what will happen next year?". It is a rhetorical question, which does not expect an answer.

It could also be the start of a non-rhetorical question. For example, a teacher may ask a class "Who knows when the Civil War started?". She is expecting students who know to raise their hand.

In your example "who" in "who knows" is a relative pronoun referring to the person referenced earlier, just like a few words earlier when it says "who wants".

The sentence could be rephrased "Should I interview a person that wants to talk in public, even though that person knows that a word out of line could mean arrest and imprisonment?". The meaning boils down to "If this person talks to me, they could easily say something that would lead to their own imprisonment."

  • Ahh you're right...
    – nodakai
    Apr 12, 2016 at 15:43
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    +1. ... someone who wants X .... but who knows Y ...
    – TimR
    Apr 12, 2016 at 17:06

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