Might vs May: Are They Interchangeable?

Do I use 'might' or 'may'?

If you have trouble deciding when to use might and when to use may, this post is for you.

As a writer and ruthless editor who strives for clarity, I prefer this clear distinction:

might implies possibility
Eric might go to the movie tonight.
(There is a possibility Eric will go to the movie.)

may implies permission
Eric may go to the movie tonight.
(Eric has permission to go to the movie.)

Yet I find multiple sources online that offer what I consider this unsatisfactory claim about the difference between might and may:

Both Eric might go and Eric may go are grammatically acceptable and differ only in the fact (fact? Says who?) that might makes the statement more tentative and the possibility more remote.

I disagree. I always choose might over may when expressing possibility.

Arizona Republic headline example

A Jewish family from Phoenix came home from a weekend away to find anti-Semitic graffiti on their mailbox stand. To convey that they were not frightened, they considered not scrubbing off the graffiti. The Arizona Republic covered the story with this headline:

Phoenix family may leave anti-Semitic graffiti uncovered

If you read only the headline, would you believe that “may leave” implies, based on some kind of residential neighborhood or homeowner’s association guideline, that the family has permission to leave the graffiti exposed?

Or does “may leave” mean that the family is considering the possibility of leaving the graffiti exposed based on a personal decision? If so, might would more accurately describe that the decision in this case is related to possibility rather than to permission.

Editing example

Here’s another place where might and may can have different implications:

  • He might use both a developmental editor and a line editor for his new novel.
  • He may use both a developmental editor and a line editor for his new novel.

Might clearly implies possibility: The writer is considering two kinds of editing for his novel.

May could imply that the publisher is offering — giving the writer the opportunity and permission — to avail himself of both developmental editing and line editing services within the scope of his contract.

Negatives with might and may

What happens when you introduce a negative to might or may?

  • Rachel might not drive to the Loop in downtown Chicago.
  • Rachel may not drive to the Loop in downtown Chicago.

The first implies that there is a possibility Rachel could decide not to drive in Chicago traffic all the way to the downtown Loop.

The second could imply that there is a possibility Rachel won’t drive to the Loop, but it also could imply that Rachel does not have permission to drive to the Loop in Chicago.

How does a reader know which to choose? Wouldn’t it be better to make statements such as this one clear by limiting use of might for possibility and may for permission?

Academic writing and may

In academic editing, I’ve observed a strong tendency to use may to imply possibility, ability and contingency, a practice that I find can lead to ambiguity or misleading statements.

For example, a Ph.D. candidate client examined the differences between training programs for those who earn an M.D., a Doctor of Medicine degree, and those who earn an O.D., a Doctor of Osteopathic Medicine degree. She made a statement similar to this about her findings:

Those who design training programs may use this data when creating, justifying, and describing first-year medical-school curriculum.

Is the writer implying that her data might (have the possibility to) be useful in creating curriculum for training doctors?

Or is the writer suggesting that those who design training programs may (have permission to) use her copyrighted information?

The implications of might versus may in cases such as this could be significant.

Everyday examples that clarify use of might and may

To express possibility:

  • It might rain tomorrow.
  • He might be late and miss dinner.
  • She has trained so much that she might actually win.

To ask permission:

  • May I attend the Tuesday board meeting?
  • May I park in the VIP lot on Tuesday?
  • May she use the school’s Olympic-size pool to train?

To grant permission:

  • You may attend the Tuesday board meeting.
  • You may park in the VIP lot on Tuesday.
  • She may train in the school’s swimming pool.

To deny permission:

  • You may not attend the Tuesday board meeting.
  • You may not park in the VIP lot on Tuesday.
  • She may not train in the school’s swimming pool.

To express wishes:

  • May you enjoy your vacation.
  • May your apple pie be the best ever.
  • May your team win the state championship.

To those who claim that might and may are interchangeable or that there is a small degree of difference between their meanings, I say please reconsider.

In the interest of clear communication, let’s stick to might when suggesting possibility and may when suggesting permission.

Silly spellcheck: I encourage writers to not rely 100% on spellcheck. When I used it to review a draft of this blog post, it highlighted every use of may, suggesting that I capitalize it. Hey, silly spellcheck, I am not writing about the month of May.

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Kathy Watson

Kathy Watson has a love/hate relationship with grammar; she loves words and the punctuation that helps them make sense, yet she hates those pesky rules. A self-proclaimed ruthless editor, she prefers standard usage guidelines of The Associated Press Stylebook. Her easy-to-use Grammar for People Who Hate Rules helps people write and speak with authority and confidence. She encourages and welcomes questions and comments. (Email)

8 thoughts on “Might vs May: Are They Interchangeable?

  1. AvatarJason DeBord

    Kathy,
    Like many of your readers, I fell into the “might or may” trap of thinking in terms other than permission or wishing. May means “stronger possibility than might.” That’s what the Interwebs told me so it must be true. Ug. I could have made it so much easier on myself by remembering back to when I was just a wee lad and would ask mom if I could go outside and play. If mom answered “you might…” I might have filled in the blank as “…if you want to risk making me REALLY upset with you.” No, instead, mom answered (usually) “You may.”

    I have seen the light.

    Reply

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