He must/will/can/ have died.

[Thomas1]

I am trying to iron out the difference between must, can and will used for concluding in the past. The threads I’ve browsed don’t give me a clear answer.
Here’s some made-up context:
I am pretty sure a colleague of mine died on a ship that sunk during its cross to Australia three weeks ago. I don’t know it however because his body hasn’t been found yet. I might say:
He must have died.
He can have died.
He will have died.

Are they all fine in this context?
What would be the difference between those sentences please?

Thank you,
Tom

 

[nmkit]

Thomas1

I would say that he "must have died".

 

[kalamazoo]

"He must have died" = I am pretty sure he has died

"He can have died" - I can't even think of a context in which you could say this

"He will have died" - this would only work in some specific contexts - "My father is gravely ill and he will have died by the time you read this letter"

Another possibility "He could have died" = there was a plane wreck and there is some possibility that he could have died - I really don't know but it's not impossible

 

[Franzi]

"He must have died."
I don't have evidence, but I'm sure he died.

"He could have died."
"He might have died."
I think it's possible he died, but not certain.

"He can have died."
This is ungrammatical for me.

"He will have died."
This could be grammatical in another context, but I wouldn't use this tense here.

 

[Dmitry_86]

1) He must have died - it is an assumption
2) He can have died - it is a possibility ("may", "might", "could" are very close in meaning here in place of "can")
3) He will have died - if you know that his disease is untreatable and he will have died by next month, for example

 

[Algonzo]

I have to agree that "he can have died" sounds wrong. I can't imagine hearing or saying this in any context. "He could have died" is 65% sure, or "he must have died" is 95% sure

 

[El escoces]

In the circumstances described, only "must have" is correct.

 

[Dmitry_86]

In fact "can have died" also seemed slightly unnatural to me as I have never heard it from the native-speakers or encountered in literature. But I did not dare say it is wrong. Now I see the point. Of course, "could/may/might have died" are more spread.

 

[Algonzo]

Not if it's the survivor man and the ship sunk near an island, in which case one could be more optimistic and "He could have died", or "He might have died" may also be correct.

 

[Loob]

Hi Tom

He can have died is not possible here.

We don't use "can" in the affirmative for speculation/deduction (though we do use negative "can't" for this purpose).

As to the difference between "must have died" and "will have died", I think I use "will" for speculation/deduction when the conclusion I'm drawing is relatively inconsequential: "Oh, that'll be the postman", for example. I'd be more inclined, here, to use the 'weightier' "he must have died".

 

[El escoces]

Interesting that although "He can have died" is quite wrong, "he can't have died!" is quite correct!

EDIT: typed without having seen how Loob's great mind had thought alike!

 

[Porteño]

Expanding the sentence a little and being speculative it would be possible to say something like:

His plane crashed three weeks ago, he will have died by now as there is no land anywhere near where the plane is said to have gone down.

Of course, the more usual way of saying it, as I would myself, would be 'he must be dead by now'. I just wanted to point out that the other is not entirely impossible.

 

[Thomas1]

Oh, the amusement with English modal verbs...

[...]
As to the difference between "must have died" and "will have died", I think I use "will" for speculation/deduction when the conclusion I'm drawing is relatively inconsequential: "Oh, that'll be the postman", for example. I'd be more inclined, here, to use the 'weightier' "he must have died".

Hi Loob,

Could you please elaborate on "the conclusion I'm drawing is relatively inconsequential"?
I find the conclusion in the example given by Porteño quite consequential, and now am grasping at straws trying to iron out the difference between "will" and "must".

Tom

 

[kalamazoo]

I think "That'll be the postman" sounds rather BE. As an AE speaker, I would probably say "That must be the postman" or "He must have died" as both expressing possibilities that I think are likely even though I am not 100% sure.

"will" sounds to me like a factual statement of what I believe is definitely going to happen in the future (e.g. "On Thanksgiving, people will eat a lot of turkey and cranberry sauce." ). I wouldn't usually use "will" for speculation.

 

[El escoces]

I think "That'll be the postman" sounds rather BE. As an AE speaker, I would probably say "That must be the postman" or "He must have died" as both expressing possibilities that I think are likely even though I am not 100% sure.

"will" sounds to me like a factual statement of what I believe is definitely going to happen in the future (e.g. "On Thanksgiving, people will eat a lot of turkey and cranberry sauce." ). I wouldn't usually use "will" for speculation.

But if "probably" is added, it becomes less definite....that'll probably be the postman now sounds LESS definite than that must be the postman.

However I agree that is another BE/AE difference - I would also say "That'll be the postman"; or, when waiting for a phone call, I might say "That'll be him now" (whereas of course it might be anyone - and "That must be him" would sound similarly illogical, unless in either case one accepts that one is not being literal).