May or Can?

Carol in Texas asks:
We attended a baseball game recently where helpers were spaced around the stadium with signs stating “How Can I Help You?”

Isn’t the actual correct usage “How May I Help You?”

This question has really been bothering my entire family, and we are split down the middle of which is right or wrong, may vs can.

The distinction between the two is often blurred. But "can" refers to actual ability to do something:
He can play the piano.
They can't score a goal even when they try.
We can get there by noon if we leave now.

"May" involves choice and sometimes uncertainty:
You may leave the room when you finish the test.
If the traffic is good, we may get there by noon.
They may score a goal if they get a lucky break.

Suppose some bashful guy approaches a lovely girl and asks: "Can I take you to the dance?" Well, no doubt he can, if he's got access to a car or cab fare. Instead he should ask: "May I take you to the dance?" In other words, will you choose to go to the dance with me?

So in the case you mention, the signs should say: "How May I Help You?" Presumably the helpers can help you—that is, they have the training and ability. But until you tell them what you need, they're uncertain; it's up to you to choose.

Comments

[Brett]

The answer to the question is clearly set out in any major dictionary. Take, for example, the Longman Dictionary of Contemporary English's entry for 'can':
2. [requesting] (spoken) used to ask someone to do something or give you something:
Can I have a cigarette, please?
Can you help me lift this box?
3. [allowed] to be allowed to do something or to have the right or power to do something:
You can't park here - it's a no parking zone.
'Can we go home now, please?' 'No you can't.'
Any police officer can insist on seeing a driver's license.

And, as Merriam Webster's Online dictionary says, "The use of can to ask or grant permission has been common since the 19th century and is well established, although some commentators feel may is more appropriate in formal contexts. May is relatively rare in negative constructions (mayn't is not common); cannot and can't are usual in such contexts."

The overlap in these two words is because the ability to do something will often depend on acquiescence from someone else. You can't help them if they don't tell you what they need help with. Finally, it should be noted that this kind of overlap in meaning is hardly unique.