# May/might/can/could



## Monica238

Does the meaning change much depending on which modal verb I use? 


1.The hostages may not have been released yet.

2. The hostages might not have been released yet.

3. The hostages could not have been released yet.

4. The  hostages can't have been released yet .

5. She couldn't/can't/may/might not have been sleeping when you called her.


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## heypresto

1 and 2 mean the same. 

Depending on the context (which you haven't given) 3 and 4 could mean the same.


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## Monica238

heypresto said:


> 1 and 2 mean the same.
> 
> Depending on the context (which you haven't given) 3 and 4 could mean the same.


It's from one of my textbooks. There was no context. It was given as a standalone sentence.
But what about the fifth sentence?


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## heypresto

The answer to #5 is yes, the meaning changes depending on the modal verb used.


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## Monica238

heypresto said:


> The answer to #5 is yes, the meaning changes depending on the modal verb used.


Do you mean  3."The hostages could not have been released yet" means they wouldn't have been released at some point in the past. It wasn't possible then 

 But 

4. The hostages can't have been released yet. We use it as a logical deduction. They can't be released yet and thus  haven't been released yet.

5. She couldn't have been sleeping when you called her. It wasn't possible  that she was asleep then. 
But 
She can't have been sleeping when you called her. I don't understand what it could mean


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## Glasguensis

We don’t know what 3 means without context. One of the possibilities is that it means the same as 4. 

In 5, couldn’t and can’t have the same meaning.


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## Monica238

Glasguensis said:


> We don’t know what 3 means without context. One of the possibilities is that it means the same as 4.
> 
> In 5, couldn’t and can’t have the same meaning.



Do you  mean #3  has this meaning I wrote: "they wouldn't have been released at some point in the past. It wasn't possible then.  But it can also have the  meaning of #4: 

"We use it as a logical deduction. They can't be released yet and thus haven't been released yet?"


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## se16teddy

3 doesn’t really have a meaning on its own. Without context, it is just confusing.
I suppose it has several potentially justifiable meanings: with context, it might possibly work OK.


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## Monica238

se16teddy said:


> 3 doesn’t really have a meaning on its own. Without context, it is just confusing.
> I suppose it has several potentially justifiable meanings: with context, it might possibly work OK.




Is the explanation/meaning of 
  4 correct? The hostages can't have been released yet. We use it as a logical deduction. They can't be released yet and thus haven't been released yet.


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## Uncle Jack

Monica238 said:


> Is the explanation/meaning of
> 4 correct? The hostages can't have been released yet. We use it as a logical deduction. They can't be released yet and thus haven't been released yet.


(4) could use "can't" for logical deduction, but it is a considerable leap to go from deducing that they haven't been released yet to saying that they actually haven't been released yet.
However, I don't see why anyone would use "can't" for a logical deduction in (4). It could express incredulity at being told they have been released, or it could be express a firm conviction that they haven't been released based on nothing whatsoever. It might express an impossibility, although I don't see how this is possible here.

As is so often the case with questions on this forum, this is all backwards. Give us the context, and we might be able to explain the meaning. Present a sentence without any context, and we interpret it according to what we imagine the situation to be. Some people have rather more vivid imaginations than others. In real life, there is always context.


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## dojibear

Uncle Jack said:


> As is so often the case with questions on this forum, this is all backwards.
> 
> Present a sentence without any context, and we interpret it according to what we imagine the situation to be.


In other words, all assumptions (even "logical assumptions") are wrong. Fluent readers *do not *read 8 words and puzzle over them for 3 minutes. That is not how language works. If you do that, you are reaching logical conclusions that the speaker did not intend. That is not communication. That is a game using words.



Monica238 said:


> Does the meaning change much depending on which modal verb I use?


Some learners think that a sentence itself has meaning. That is false. 

Writers use sentences to express mental ideas. How do we know what meaning *you *are expressing in each sentence? None of these sentences are valid English, without more words. Nobody says 8 words and then dies.


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## Glasguensis

It’s like the meaning of « No ».
Sometimes no means absolutely not
Sometimes it means probably not
Sometimes it means I can’t be bothered thinking about my answer 
Sometimes it means « Gosh, really? »
Sometimes it means « Stop! »
And I could go on all day. We can’t give you all the possible meanings a short sentence could have. Context is everything.


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## Monica238

Uncle Jack said:


> (4) could use "can't" for logical deduction, but it is a considerable leap to go from deducing that they haven't been released yet to saying that they actually haven't been released yet.
> However, I don't see why anyone would use "can't" for a logical deduction in (4). It could express incredulity at being told they have been released, or it could be express a firm conviction that they haven't been released based on nothing whatsoever. It might express an impossibility, although I don't see how this is possible here.
> 
> As is so often the case with questions on this forum, this is all backwards. Give us the context, and we might be able to explain the meaning. Present a sentence without any context, and we interpret it according to what we imagine the situation to be. Some people have rather more vivid imaginations than others. In real life, there is always context.



I agree regarding the context, but there wasn't any. The sentence is from a book. But it is true that the construction "can't have done" is used  to express  a logical deduction but also the following as you said: "it could express incredulity at being told they have been released, or it could be express a firm conviction that they haven't been released based on nothing whatsoever". While
"Could not have done" means "would not have done" so it has a conditonal meaning? It's mentioned in Raymond Murphy's English Grammar textbook: Read this information about Ken:

Ken didn't do anything on Saturday evening.
Ken doesn't know anything about machines.
Ken was free on Monday afternoon.
Ken was short of money last week.
Ken's car was stolen on Monday.
Ken had to work on Friday evening.


Some people wanted Ken to do different things last week but they couldn't contact him. So he didn't do any of these things. You have to say whether he could have done or couldn't have done them.

1) Ken's aunt wanted him to drive her to the airport on Tuesday.
Answer: He couldn't have driven her to the airport (because his car had been stolen).

Etc.

The idea is that it would not have been possible for Ken to drive his aunt to the airport, even if she had been able to contact him.

And my second question is as Glasguensis said 
"We don’t know what 3 means without context. One of the possibilities is that it means the same as 4" 
then "could have done"  has all the meanings you listed that "can't have done" has. Right?


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## se16teddy

Monica238 said:


> Is the explanation/meaning of
> 4 correct? The hostages can't have been released yet. We use it as a logical deduction. They can't be released yet and thus haven't been released yet.


Yes. 4 means that I infer from known facts that they have not been released yet. Of course, different people will have different views about what inferences it is safe to draw from known facts; and wise speakers know this.


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## Glasguensis

Both can’t have done and couldn’t have done *can* be used to express a logical deduction as you describe. They can both also have *other* meanings. The context determines which meaning they have and whether they are interchangeable.


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## Uncle Jack

Monica238 said:


> While "Could not have done" means "would not have done" so it has a conditonal meaning?


"Could" does not mean "would". It might mean "would not have been able to", and so it might have a conditional meaning, or it could express an impossibility to which no condition is attached at all, or it could be a logical deduction. Raymond Murphy's English Grammar textbook provides context, so we know that the meaning of "could not have done" is "would not have been able to do" in the example you give. This is not necessarily the case in your own sentence, and although "The hostages would not have been able to have been released yet" is a possible meaning, it does not seem to me to be a likely thing to want to say.


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## Monica238

Glasguensis said:


> Both can’t have done and couldn’t have done *can* be used to express a logical deduction as you describe. They can both also have *other* meanings. The context determines which meaning they have and whether they are interchangeable.



The problem is that our textbooks don't say that. So all the possible meanings of 4 "The hostages can't have been released yet" are the following ones that Uncle Jack explained.   A logical deduction.  But also  "It could express incredulity at being told they have been released, or it could be express a firm conviction that they haven't been released based on nothing whatsoever. It might express an impossibility."

"Could not have done" in 3  as you said  "The hostages could not have been released yet."  could  mean  the same as 4.  So it can have all the possible meanings of 3. Both can be used to express a logical deduction as well the  other meanings Uncle Jack mentioned .  

But in the book's example about what Kent would not have been able to do which doesn't apply to the hostages example, would a  native speaker use "can't have done" in the book's example instead of "couldn't have done?
As in "Kent can't have driven her to the airport" instead of "could not have driven her to the airport?"


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## Glasguensis

The fact that your textbook does not explain every possible meaning is not « a problem » : textbooks and dictionaries cannot possibly list every single meaning and usage- if they tried to they would take so long to compile that they’d be out of date.

In your Ken example it is more natural to use couldn’t.


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## Uncle Jack

Monica238 said:


> But in the book's example about what Kent would not have been able to do which doesn't apply to the hostages example, would a native speaker use "can't have done" in the book's example instead of "couldn't have done?
> As in "Kent can't have driven her to the airport" instead of "could not have driven her to the airport?"


No, because that example was referring to a hypothetical ability in the past. This requires "couldn't" and the perfect infinitive. You cannot use "can" for a hypothetical situation. I suppose a speaker could have chosen to use "couldn't" + plain infinitive for a real impossibility in the past, but the question is not structured in this way. I don't see any way that "can't" could be used, because the sentences are wholly about the past.


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## Monica238

Uncle Jack said:


> No, because that example was referring to a hypothetical ability in the past. This requires "couldn't" and the perfect infinitive. You cannot use "can" for a hypothetical situation. I suppose a speaker could have chosen to use "couldn't" + plain infinitive for a real impossibility in the past, but the question is not structured in this way. I don't see any way that "can't" could be used, because the sentences are wholly about the past.



And "could not have been released" doesn't express a hypothetical situation in the example about hostages. Right?


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## Monica238

Glasguensis said:


> The fact that your textbook does not explain every possible meaning is not « a problem » : textbooks and dictionaries cannot possibly list every single meaning and usage- if they tried to they would take so long to compile that they’d be out of date.
> 
> In your Ken example it is more natural to use couldn’t.



Is the part that I rephrased to make sure I don't misunderstand correct?

"So all the possible meanings of 4 "The hostages can't have been released yet" are the following ones that Uncle Jack explained. A logical deduction. But also "It could express incredulity at being told they have been released, or it could be express a firm conviction that they haven't been released based on nothing whatsoever. It might express an impossibility."

"Could not have done" in 3 as you said "The hostages could not have been released yet." could mean the same as 4. So it can have all the possible meanings of 3. Both can be used to express a logical deduction as well the other meanings Uncle Jack mentioned."


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## Glasguensis

Monica238 said:


> And "could not have been released" doesn't express a hypothetical situation in the example about hostages. Right?


*We don’t know : there is no context.*



Monica238 said:


> Is the part that I rephrased to make sure I don't misunderstand correct?
> 
> "So all the possible meanings of 4 "The hostages can't have been released yet" are the following ones that Uncle Jack explained. A logical deduction. But also "It could express incredulity at being told they have been released, or it could be express a firm conviction that they haven't been released based on nothing whatsoever. It might express an impossibility."
> 
> "Could not have done" in 3 as you said "The hostages could not have been released yet." could mean the same as 4. So it can have all the possible meanings of 3. Both can be used to express a logical deduction as well the other meanings Uncle Jack mentioned."


Those are not *all* of the possible meanings.
We can’t give you a list of all the possibilities because we can’t think of all the possible contexts.


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## Monica238

Glasguensis said:


> *We don’t know : there is no context.*
> 
> 
> Those are not *all* of the possible meanings.
> We can’t give you a list of all the possibilities because we can’t think of all the possible contexts.



Regarding this part:
And "could not have been released" doesn't express a hypothetical situation in the example about hostages. Right?
We don’t know : there is no context."

I mean how can it express a hypothetical situation in the past if there is "yet" in the sentence?
"They couldn't have been released yet."


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## Glasguensis

For example we’re discussing a siege : it’s odd that the robbers ordered so many pizzas at 4pm - were they trying to make us think there were ten of them? No wait, the hostages couldn’t have been released yet, so the robbers must have ordered for them too.


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## Monica238

Glasguensis said:


> For example we’re discussing a siege : it’s odd that the robbers ordered so many pizzas at 4pm - were they trying to make us think there were ten of them? No wait, the hostages couldn’t have been released yet, so the robbers must have ordered for them too.



And because it's the hypothetical situation in the past "can't have been released yet" can't be used. Right? In  Murphy's example it would be wrong too.


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## Glasguensis

It is the same as Murphy’s example: I said “couldn’t” is preferable and @Uncle Jack went further and said “can’t” would be incorrect.


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## Uncle Jack

As far as I am aware, "can" and "can't" cannot be used for a hypothetical situation at all (but I am willing to be proved wrong).

The word "yet" in your sentence could mean it is about an action in the past or a state in the present (perhaps there are other possibilities as well). I don't think that it gives any clues as to whether it is real or hypothetical. Often you can tell by looking at the verb tense, but "could" has so many different uses that I would not like to rule anything out.


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## Monica238

Glasguensis said:


> For example we’re discussing a siege : it’s odd that the robbers ordered so many pizzas at 4pm - were they trying to make us think there were ten of them? No wait, the hostages couldn’t have been released yet, so the robbers must have ordered for them too.





Uncle Jack said:


> As far as I am aware, "can" and "can't" cannot be used for a hypothetical situation at all (but I am willing to be proved wrong).
> 
> The word "yet" in your sentence could mean it is about an action in the past or a state in the present (perhaps there are other possibilities as well). I don't think that it gives any clues as to whether it is real or hypothetical. Often you can tell by looking at the verb tense, but "could" has so many different uses that I would not like to rule anything out.



This sentence is taken from L. G. Alexander's LONGMAN ENGLISH GRAMMAR: (from 11.15 of the book)

"He can't have told you anything I don't already know."

But it's again deduction not a hypothetical situation. Right?


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## Glasguensis

Yes


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## Monica238

Glasguensis said:


> Yes



And because it's a deduction either "can't have told you and "coudn't have told you" work. 


Or if I tell my husband that this morning  my neighbor Anna  passed me by without saying "hello". I was so surprised. We always greet each other. And my husband says: "if she didn't say "hello" she "can't/couldn't have seen you". It's again a deduction. Right?


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## Glasguensis

Yes


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## Monica238

Glasguensis said:


> Yes


One question remains open if  "can" and "can't" can used to takk about a hypothetical situation.


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## Glasguensis

In what way does that question “remain open?” Unless I missed it, that hasn’t been discussed in this thread.


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## Monica238

Glasguensis said:


> In what way does that question “remain open?” Unless I missed it, that hasn’t been discussed in this thread.



I was referring to Uncle Jack's comment. Is it a good idea to start a new thread? But I will  be asked to provide the context for my sentence, but I can't provide a sentence for my question. My question is if 'can' can be used in hypothetical situations.


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## Glasguensis

Yes, it can.


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## Monica238

Glasguensis said:


> Yes, it can.



Could you please write an example?


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## Glasguensis

If you win the lottery you can buy a Ferrari


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## Monica238

Glasguensis said:


> If you win the lottery you can buy a Ferrari



If I change it into a hypothetical situation in the past then it would be  "If you had won the lottery, you could have bought a Ferrari." Right?


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## Glasguensis

Yes


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## Monica238

Glasguensis said:


> Yes





Glasguensis said:


> Yes



But can't I use "may", "might" or "could" in your example?
If you win the lottery you could/may/might buy a Ferrari.


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## Glasguensis

Yes


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