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To be honest, I am of the opinion that there is a clear distinct between the two.

I think the difference between phrasing a question as 'may I' and using 'can I' instead, is that the first seeks the permission of the person to whom the question will be addressed to allow the question to be asked.

In other words, you are requesting their attention, space, time - you are not assuming - or presuming - that you have a right to ask the question or receive an answer. To ask a question thus is signalling recognition of this.

The second is self evident. Anyone who has mastered speech, or writing 'can' - or, is able to - ask a question.

Clearly, when people are asking if they can ask a question, they are seeking permission.
 
Clearly, when people are asking if they can ask a question, they are seeking permission.

Perhaps. Or it may be one of those slight differences in emphasis and interpretation in the way English is spoken (and written) Across the Pond.

For my part, I tend to make a distinction between 'can' and 'may', even when used in an almost identical context of asking a question. To my ear, the verb 'can' is stronger, and almost presumes permission; 'may' seeks consent to carry out the action requested, it doesn't presume to already have it.

In the novel, 'East of Eden', by John Steinbeck, there is a fascinating discussion on the distinctions to be drawn between the words 'can', and 'may' as well as the use of 'shall' (when used as a command).
 
Scenario: little Johnny's friend Steve is going to the skatepark, little Johnny needs to get his moms permission first, little Johnny's mom says no, and little Johnny replies with "but mom! Steve is doing it!". To which the mom says if Steve were to jump off a bridge would you do it?

So stupid. Why would you compare something fun to doing something awful? Of course I don't want to jump off a bridge, but if a friend is doing something fun hell yeah I want to join.

This was never told to me by my parents, but I hear other parents say it and it makes my skin crawl. Might as well ask if they want to be burned in a fire rather than going on a road trip. Horrible comparison Susan.
 
Scenario: little Johnny's friend Steve is going to the skatepark, little Johnny needs to get his moms permission first, little Johnny's mom says no, and little Johnny replies with "but mom! Steve is doing it!". To which the mom says if Steve were to jump off a bridge would you do it?

So stupid. Why would you compare something fun to doing something awful? Of course I don't want to jump off a bridge, but if a friend is doing something fun hell yeah I want to join.

The analogy is between two things that can be considered (by some) to be fun, but dangerous. There are people who enjoy jumping off bridges, just as there are people who enjoy skateboarding.

In any event, the parent is emphasizing the danger in the compared activities - because the child is only seeing the fun part.
 
Scenario: little Johnny's friend Steve is going to the skatepark, little Johnny needs to get his moms permission first, little Johnny's mom says no, and little Johnny replies with "but mom! Steve is doing it!". To which the mom says if Steve were to jump off a bridge would you do it?

So stupid. Why would you compare something fun to doing something awful? Of course I don't want to jump off a bridge, but if a friend is doing something fun hell yeah I want to join.

This was never told to me by my parents, but I hear other parents say it and it makes my skin crawl. Might as well ask if they want to be burned in a fire rather than going on a road trip. Horrible comparison Susan.

That's because "Steve is doing it" is a very poor argument in Johnny's favor. The bridge jumping scenario is used to illustrate the point.
 
The phrase that needs to go is the one people whisper when they're on the phone with you and they're looking something up. "tch-tch-tch-choo." Or some variation of that.
 
Get down on the ground and put your heads over your head.

it's time people stopped shouting this at me.
 
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