Do serious grammarians endorse the "Can I"/"May I" distinction?

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...

Solution 1:

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:

Can we, with manners, ask what was the difference?

From Shakespeare, All's Well that Ends Well, Act I, Scene 1:

Ay. You have some stain of soldier in you: let me ask you a question. Man is enemy to virginity; how may we barricado it against him?

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.

Solution 2:

This is a matter of context and style, not some sort of esoteric detail that "serious grammarians" (which I won't dwell on) might idly debate.

In a casual context, use the words "can" and "may" interchangeably with an emphasis on "can" for everyday purposes.

Keep this in mind though: Each of the two words has a distinct meaning. For contracts or the law, this difference is observed. Personal experience for justification: I was with a friend in traffic court in Arizona. Presiding judge had approx 100 cases to rule on, none involving injuries or damage. When he got to my friend's case, he sent the plea agreement back to the Assistant District Attorney, because there was ambiguity due to the use of "may" instead of "shall". "May pay a fine" is an option, a choice, whereas "shall pay a fine" is mandatory.

The judge was presiding over misdemeanor and minor criminal traffic citations in a small town in Arizona, and court was in session for three hours with no break. Yet he noticed an inconsistency in wording with a very quick scan of the paper work, and deemed it important enough to involve the DA's office for five minutes to resolve. So don't dismiss the importance of such distinctions. However, context should be your first criteria, then grammatical "correctness".

Solution 3:

I think a serious descriptive grammarian would tell you what you already know: can I is more common and may I indicates more formal style, but in this kind of context they mean exactly the same thing.

However that does not tell you which one you should use. For that, ask a writer whose style you’d like to emulate; consult a usage guide; or stop worrying about it. :)