Can vs. May

Although, traditionally, can has meant “to be able” and may has meant “to be permitted” or to express possibility, both can and may are commonly used interchangeably (especially in spoken, informal language) in respect to permission. Even the Oxford English dictionary informs us that the permission use of can is not incorrect, but it’s better and more polite to use may in formal situations.

Example: He can hold his breath for 30 seconds.

Meaning: He is able to hold his breath for 30 seconds.

Example: He may hold his breath for 30 seconds.

Meaning #1: It is possible that he will hold his breath.

Meaning #2: He has permission to hold his breath. (This meaning is unlikely.)

Example: May/Can I go to the mall tonight?

Regardless of whether you choose can or may here, it is clear that permission is being requested.

In spoken English, a request for permission is generally answered with can, cannot, or can’t, rather than with may or may not, even if the question was formed using may. (Although mayn’t is a word, it looks and sounds strange even to native speakers.)

Example of Dialogue:

“May I go to the mall tonight?”
“No, you can’t/cannot go.” OR “Yes, you can go.”

Occasionally, you may hear someone say something like, “I cannot but argue when you say such silly things.” The expression cannot but argue is actually an old-fashioned way of saying “cannot help arguing.” You may also hear the expression can but, which means “can only.”

Example: We can but do our best to arrive on time.


Pop Quiz

1. Can/May you imagine a world without war?
2. Can/May I call you for a date?
3. She can/may run faster than anyone else on the team. (able to)


Pop Quiz Answers

1. Can you imagine a world without war?
2. Can OR May I call you for a date?
3. She can run faster than anyone else on the team.

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7 Comments on Can vs. May

7 responses to “Can vs. May

  1. Kent says:

    Why is it that when a group of people are intentionally looking for something, you hear a person say, “Let’s see if we can’t find a way to get the job done” vs what I always think should be worded, “Let’s see if we can find a way…” I hear this all the time and can never understand why the negative is used.

  2. Mary W. says:

    I recall from my parochial school education that when referring to permission, “may” should be used when speaking in the first person, and “can” should be used when speaking in the second and third person.

    • If we understand you correctly, you would follow this format:
      May I answer the question? This sounds fine to the ear.
      Can you answer the question? “May you answer the question?” does sound funny, but its inversion doesn’t: “You may answer the question.”
      Can she answer the question? “May she answer the question?” also sounds just fine to the ear and is solid grammatically.

      It seems that your parochial learning provided reasonable but incomplete guidance.

  3. Bill says:

    When I was a kid and asked my father, “Can I go out to play?” he would answer, “You may if you can.”

  4. Martha Locke says:

    I was always taught “may” indicates a request, “can” indicates ability, which is why you wouldn’t say “can I?” unless, for example, you’re asking yourself or a doctor whether or not you are able physically/mentally/whatever to do a thing. You may decide you “can” (climb Mount Ranier) but you still might have to ask your parents permission (if you are 9 yrs old). Mother, may I? My parents might respond, “Yes, you can, but you may not.”

    Can indicates ability to do something, not a request.

    It’s subtle and may be out of date or old-fashioned but I’ll stick with the old way. For example if you’re posing a question “Can I do this?” vs “May I do this?” it’s ability vs ability/eligibility.

    • We agree with using can for ability and may for permission in formal situations, which are up to you to decide—with teachers, parents, work colleagues, etc. Simply be aware that English has many situations where what we’ve learned as rules could more accurately be called guidelines.

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