[General] must have closed/should have closed

[vil]

Dear teachers,

Would you be kind enough to explain to me in plain English the difference between the meaning of the following sentences?

He must have closed the window.

He should have closed the window.

Here is adduced a difficult case for usage of modal verbs.

Thank you for your efforts.

Regards,

V.

 

[sarat_106]

Dear teachers,

Would you be kind enough to explain to me in plain English the difference between the meaning of the following sentences?

He must have closed the window.
He is bound/obliged by an absolute or imperative requirement to close the window.

He should have closed the window.
It is his duty to close the window and he could not have forgotten his duty to cloae the window.

Thank you for your efforts.

Regards,

V.

Skp

 

[MASM]

Dear teachers,

Would you be kind enough to explain to me in plain English the difference between the meaning of the following sentences?

He must have closed the window. I think this means that the window is closed, so he must have closed it.

He should have closed the window. This one means that the window was open, he should have closed it, but he didn't

Thank you for your efforts.

Regards,

V.

I hope that I'm right, and that my explanation can help you.
xxx

 

[vil]

The meaning of the sentences in question in my original post above we might interpret in such the same manner as the following two sentences.

He had to do it.

He should have done it.

Here is adduced also a difficult case for usage of modal verbs.

Regards,

V.

 

[IHIVG]

I agree with MASM.
The 'must' in the first sentence seems to be used in the same way as in 'You must be joking'.
Someone closed the window. It is likely that he closed it.
The 2nd implies that it was imperative that he close the window, but he didn't.

 

[magimagicE]

He must have closed the window.

The action of closing the window has occurred, and the author is speculating who did it. The conlcusion is that "He" did it.

The sentence could also be interpreted as the answer to the question, "why is the window closed?"

He should have closed the window.

The action of closing the window which was meant to occur has not occurred. The author is looking back with hindsight as a result of a bad or the well-known bad consequences of not closing the window (eg the place has been burgled or will be burgled at some point); and how the bad outcome could be or can be avoided.

This implies that there was a right course to take, but that it wasn't taken.


He had to do it.

The action has occurred. The situation is such that no other outcome is possible.

He should have done it.

There was a right course of action, but that it was not taken. There is a sense of regret attached to this sentence.