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Hi,

I have difficulty seeing the difference between the modals 'could' and 'can' in some normal sentential situations. My impression of things is that the use 'can' is somewhat limited to physical capacity or physical capability, whether people involved can do it physically; whereas, 'could' is usually used in conjunction with the concept of willingness or permission. But sometimes, it is very hard to make distinctions based on them.

1. Could you pass me the salt? I need to add some flavor to my dish. -- Here, I think 'willlingness' and not physical capability is at play.

2. Can you come to my birthday party? -- Here, I think, many people would say it is physical capability -- whether he is capable of coming to the party and not whether he is willing to come.

3. Could you come to my birthday party -- Unlike the above, I think 'could' here deals with his willingness.

But, it seems to be too restrictive to reflect the real-world usage of the modal 'can' to physical capacity or physical capability as it was done in the case of no. 2. I think in real life, the usage of both 'can' and 'could' cross lines and they are used in a somewhat similar fashion -- and that is the source of my confusion. Can you help?
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I'm not into modals, but I think both can and could denote physical capability. I can lift this box. I could lift this box. (with or without implied conditions)

With polite questions people often don't say what they mean, because they don't want to put the person addressed in a bind. If you really want to know if the person will come, Ask him. "Will you come to my party?" That covers both willingness and capability.

I'd say "could" is less committal than "can," perhaps because of it's possible implied conditions, It's easier to say "No" without offending the questioner. I agree that between the two, if the questioner wishes to address capability, he should use "can." But without any additional context to suggest that's their intention, most questioners would use "can" and "could" interchangeably. It depends a lot on the habits of the person asking, and on the social nature of the situation. "Could" is more polite; "can" is more direct. And some people are more direct by nature.

If there had been a previous conversation in which the invited person suggested he might have a conflict (Implying, perhaps falsely, that he'd be willing if he could clear the conflict), then the questioner would subsequently use "can" to reinvite him.

Many people will say "Can you pass me the salt?" You wouldn't hear it at a White House white-tie-and-tails dinner, except possibly by George himself. But no one under any conditions would take it to mean, "Are you capable of passing me the salt?"

Probably that doesn't help you at all.

- A.
AvangiI'm not into modals, but I think both can and could denote physical capability. I can lift this box. I could lift this box. (with or without implied conditions)
Hi Avangi
Very good overall. Emotion: smileCould doesn't normally refer to a single instance of physical capability, though. It is fine in a sentence like: I could swim when I was five years old.
Cheers
CB
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Thanks, CB. I wasn't too happy with that example either.

How about as a question? If I ask, "Do you think you could lift this box?" would it only be taken as "Would you mind lifting this box for me?", or could it be, "Could you lift this box (if you had to - understood)?"?

Best wishes, - A.
Hi,
every modal can have a billion meanings, depending on the context. Fortunately, most of those billions meanings are in the dictionaries. Unfortunately, you can't use every modal with every meaning in every situation. And often there aren't any clear-cut distinction between them or their usages.

Could you help me? is just a more polite version of Can you help me?
You don't need to associate that "can" or "could" with ability, permission or anything. My dictionary just says "used to ask someone to do something or give you something". Of course that's just one usage. It could have another meaning in another context.
AvangiHow about as a question? If I ask, "Do you think you could lift this box?" would it only be taken as "Would you mind lifting this box for me?", or could it be, "Could you lift this box (if you had to - understood)?"?
It could ([Emotion: smile]) have either meaning.
CB
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BelieverCould you pass me the salt? ... Here, I think 'willlingness' and not physical capability is at play.
No, not really. In both this version and the other, more direct version (Can you pass me the salt?), you need to make a distinction between semantic meaning and pragmatic meaning.
The semantic meaning of such a statement involves asking if someone has the physical ability to pick up the salt shaker and hand it to the person requesting the salt. It is quite literal.
The pragmatic meaning is based on the real world knowledge that the literal answer is "Yes". (Of course that person has the physical ability to do what is requested.) The real world knowledge underlying this conversational move is that we all understand that the ability to do something is a precondition for doing it. We ask the other person to reason thus: If I can/could do it, and someone is calling my attention to this fact, then I should do it in this situation. It is a disguised imperative: Pass me the salt!
_______
Note that the same reasoning applies to [Do you have to / Must you] make so much noise? although somewhat in reverse.

The semantic meaning contains a question about the necessity of making the noise. The literal answer is "No".
The pragmatic meaning is based on the real world fact that if a person has no need to something, he is able to stop doing it. Having no need to do something is a precondition for not doing it. Again, there is an underlying imperative: Stop making so much noise!
CJ