Modals used for requesting permission may or could

[xhadesx]

Hello,

I'm learning up on English modals, but I'm having issues here. I am looking up modals for requesting permission. I was told by multiple people that 'can' can be used when asking for requesting something. I realize it doesn't matter if you use it in everyday English, but I just wanted to know about 'could' and 'may'

I've been reading up on when to use 'could' and 'may' it seems you can use could with all pronouns, but when asking specifically permission then you must use the pronoun 'I'

Can I have this dance? <--- wrong? other says it is right
Could I have this dance? <--- Correct
Could you dance with me? <--- Correct
May I have this dance with you? <--- Correct
May you have this dance with me? <--- Incorrect? other says it is right

How do you determine what is right or wrong? I keep getting the answer personal preference. This doesn't apply to English in universities does it? My point being, I've read dictionaries that said ok or may with other pronouns maybe correct. I ran into this article though:

Could is used with any subject to ask for permission. For example “Could I open the window?” or “Could you open the window?” are both grammatical.

Be careful with may. When making a request using may, only I can be the subject. If you are making a formal request to dance with someone, you would say, “May I have this dance?” not “May you have this dance?” May followed by you does not express a request; it expresses a wish, as in “May you live long.”



http://learningenglish.voanews.com/cont ... 77141.html

[Joe]

For requests the main difference is in formality.

CAN informal
COULD more formal/polite
MAY formal
MIGHT very formal

[lasunpals]

Could you pls explain?

[Joe]

There seems to be some confusion between making a request (which in general is for somebody else to do sthg) and asking for permission (which in general is for you yourself to be allowed to do something). In addition, the dancing example is a little confusing because the very typical "Could I have this dance" is formulaic from a bye-gone age and in other contexts "Could you dance with me" would be the normal expression.

ASKING FOR PERMISSION
Can I have this dance (with you)? <--- POSSIBLE, INFORMAL
Could I have this dance (with you)? <--- NORMAL
May I have this dance with you? <--- POSSIBLE, VERY POLITE
Can I smoke?
Could I smoke?
May I smoke?

REQUEST
Can you dance with me? POSSIBLE, INFORMAL
Could you dance with me? <--- NORMAL
Can you open the door?
Could you open the door?

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REQUEST OR ASKING FOR PERMISSION ??????? - WHICH IS IT?

May you have this dance with me?

It depends what this unusual sentence is trying to say. On the face of it, it's "incorrect" and should be:

Could you have this dance with me?

But if I read it literally, it means:

Do you have permission (from somebody else, for example parents) to have this dance with me?

--

See also this page on can and this on could.