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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'?

RegDwigнt
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kacherese
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  • The former. It simply means you haven't shut the door. It says nothing about your general ability or chances. – RegDwigнt May 18 '15 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 '15 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 '15 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 '15 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. – John Lawler May 18 '15 at 18:19
  • It's widely acceptable in 'BrE', to the best of my knowledge. "You can't have shut the door properly" is the claim that "It must be the case that 'you' haven't shut the door properly (ie securely)". This could be achieved either by making a failed (perhaps deliberately so) attempt to shut the door, or by not attempting to shut the door at all. The language allows these possibilities, but the default understanding would be 'You made an inadequate, probably careless attempt' (though hedging is also possible, where the accuser knows full well the accusee forgot completely ... or worse). – Edwin Ashworth Dec 31 '19 at 19:58

3 Answers3

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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.

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

It can't be that you shut the door.

or

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.

stevenvh
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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.

Community
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Apollonian
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  • Hyperlinks break, and so link-only answers are not acceptable. If you want to answer the question, please include some content. – Spencer Dec 31 '19 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 – Arm the good guys in America Jan 01 '20 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 01 '20 at 17:48
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    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. – Arm the good guys in America Jan 02 '20 at 03:17