I've been told that the expression "Can you not" (Can/Could + subject + not + verb) is used in casual conversation but it's not grammatically correct. Is this the case?

I'm aware that it wouldn't be appropriate in a formal / written context. I've also heard that it's only correct when an interjection is between the subject and the verb (i.e. "Can you please not do that?" or "Can you, like, not do that?").

Also, would the use of "Could" make the expression appropriate for a polite request?

  • It's grammatical, it's called verb-phrase ellipsis (VPE). I made a post about this in my answer - skip towards the end. VPE is normal in every-day English. However it requires an established context, in order to be understood by a third-party.
    – aesking
    Apr 8, 2018 at 5:12

1 Answer 1


It may be more polite to say/ask: Would you not do that? Or Will you not do that? Could and can seem impolite, because they suggest that the other person might be incapable of doing something.

...would is more polite, because it expresses the idea of probability, and of willingness, and of the desire that something be done, whereas “could” is more in the realm of ability (yes I can).

  • That makes sense. Is the use of Can/Could grammatically correct as well? Apr 7, 2018 at 19:34
  • 1
    @Nico de Ory ~ I don't see any real problem with the grammar, technically speaking. Some people may take issue with the wording because they instinctively view it as being vaguely impolite (even if unintentional), and without understanding the precise nature of the problem, they sometimes criticize the grammar instead.
    – Bread
    Apr 7, 2018 at 19:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.