Our dog escaped! You can't have shut the door properly!

Does the phrase 'You can't have shut the door properly!' mean 'You must have shut the door in a wrong way', or 'you haven't been able to shut the door properly'?

  • The former. It simply means you haven't shut the door. It says nothing about your general ability or chances.
    – RegDwigнt
    May 18, 2015 at 10:12
  • Is it correct to simply say 'You haven't shut the door properly!' in this case without loss of meaning? And if I want to say about my general ability in past, how can I use can't\couldn't + perfect form?
    – kacherese
    May 18, 2015 at 10:22
  • "You can't have shut the door properly" is a perfectly acceptable (probably preferable, as it is a shade more polite) way to say "I don't think you shut the door properly." It is more likely to be heard in British English.
    – Robusto
    May 18, 2015 at 11:08
  • The phrasing is atypical for modern American English, though it was seen in old Bobbsey Twins books (ca 1920) and the like. (More modern would be "You must not have shut the door properly.") It implies that (some time in the past, not at the present moment) the door was not shut properly for some reason.
    – Hot Licks
    May 18, 2015 at 12:24
  • This is the Epistemic sense of can, which is a negative polarity item (and therefore can occur grammatically only in the negative -- whence can't). Note that trying to use can instead of can't produces an anomaly; may is the epistemic possibility modal that's used in the affirmative, not can. Note that can't means 'not possible', while may not means 'possible not'; this is one reason why we have a lot of modal auxiliaries. May 18, 2015 at 18:19

3 Answers 3


Since the sentence appears to refer to a single escape incident, "You can't have shut the door properly!" is more properly described by: "You must have shut the door in a wrong way" - which refers to a single incident- than by: "you haven't been able to shut the door properly", which implies more than one instance of gate-shutting incompetence.


You can write it differently, while keeping the "can't":

It can't be that you shut the door.


It's impossible that you shut the door.

So, s/he wasn't unable to shut the door, just didn't do it.
If you want to express the inability to shut it:

You can't shut the door, or
You couldn't shut the door.


This page on BritishCouncil.org called Modals - deductions from the past "focuses on making deductions about the past." It says:

We can use modal verbs for deduction – guessing if something is true using the available information. The modal verb we choose shows how certain we are about the possibility.

It also says:

We use can't have and couldn't have + past participle when we think it's not possible that something happened.

and provides these examples:

She can't have driven there. Her car keys are still here.

I thought I saw Adnan this morning but it couldn't have been him – he's in Greece this week.

  • Hyperlinks break, and so link-only answers are not acceptable. If you want to answer the question, please include some content.
    – Spencer
    Dec 31, 2019 at 20:00
  • -1 dude, because the content must not used from another website without proper attribution. in this case, making it clear that the answer/words is not yours, but those of the website you link to Jan 1, 2020 at 17:21
  • @ArmthegoodguysinAmerica Who says I shouldn't do that when it sufficiently answers the OP's question? I didn't deem it necessary to change the content. You have nothing better to do than downvote a relatively fine answer using broken English? :|
    – Apollonian
    Jan 1, 2020 at 17:48
  • 1
    You can't copy and paste without making it clear that you are quoting a site; second, answers whose entire content are copied from an outside website are not encouraged here: when you write an answer, it should be your answer. Jan 2, 2020 at 3:17

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