Just now, I wanted to ask a question that was something like, "Can I get a thorough list of all the parts of speech that a sentence can be broken down into?" But then a nagging voice appeared in my head and said,
"Of course you can! You certainly have the capability — but that's not what you want, is it." "You're asking for help, so use may."
My question is: Should I invariably trust that voice, instilled in students by grammar school teachers everywhere? What do serious linguists and language enthusiasts think about the "Can I"/"May I" distinction? Would they agree, or is it fair to say that using "can" there has become proper idiomatic English? I ask because I couldn't really think of a quick way to rephrase that sentence using "may", and began to wonder whether it was just another one of those kludgy myths megalomaniac teachers enforce on their students…
Best Answer
Repeating my answer to this related question, I searched Shakespeare's plays, and found these two examples where it appears that can and may are used in ways opposite the commonly prescribed can we/may we distinction. I don't know when or how this distinction developed or was prescribed, but my conclusion is that it is not a historical feature of English grammar.
From Shakespeare, Cymbeline, Act I, Scene 4:
From Shakespeare, All's Well that Ends Well, Act I, Scene 1:
I think the problem may be that unlike, say, German (which has dürfen) English doesn't have a modal verb which always means "to be allowed to". For example, if I say "It may be rainy tomorrow," I do not mean that I am permitting the clouds to rain. The modal verbs can and may have both been appropriated for this meaning in English, but I don't see any clear semantic reason for using one rather than the other. Without either a semantic reason for or a historical tradition of making this distinction, prescriptive grammarians are fighting an uphill battle.