Might or May?

by Craig Shrives

What Is the Difference between "Might" and "May"?

"Might" and "may" are interchangeable when they express the idea of possibility. However, here are three considerations when deciding whether to write "might" or "may":

(1) Many treat "may" as more likely than "might."

Many English speakers consider "may" to be like "probably" and "might" like "possibly." For example:
  • Sarah may be present at the party. John might be present too. correct tick
  • (Some people will consider Sarah's presence more likely than John's.)

(2) "May" can express the idea of permission.

When this creates ambiguity, use "might." For example:
  • Sarah may use the swimming pool. correct tick
  • (Does this mean "Sarah might use the swimming pool" or does it mean "Sarah is permitted to use the swimming pool"? When such ambiguity exists and you want to express the idea of possibility, use "might.")

(3) "Might have" sounds better than "may have."

Nowadays, "might have" and "may have" can also be used interchangeably, but historically (in the 19th century) "might have" was more common. As a result, "might have" still sounds more natural for most people. For example:
  • Sarah may have spoken to the CEO. correct tick
  • Sarah might have spoken to the CEO. correct tick
  • (Both of these are correct, but "might have" sounds more natural.)
might or may?

Is "May" More Likely Than "Might"?

Look at these two sentences:
  • I might go to the concert. correct tick
  • I may go to the concert. correct tick
Nowadays, "might" and "may" express equal levels of possibility.

However, be aware that some of your readers could treat "may" as more likely than "might." In other words, with the first example above, they could treat the likelihood of you attending the concert as, let's say, a 40% possibility. However, with the second example (the one with "may"), they could treat this as, let's say, a 60% possibility. You should not think of this weighting as the difference between "might" and "may" though — most people do not apply that idea these days.

Eliminate Ambiguity with "May"

Be aware that may can be used for permission. For example:
  • May I go to the concert?
  • (This means the same as "Am I allowed to go to the concert?")
It follows therefore that using "may" could create ambiguity. For example:
  • I may go to the concert.
  • (This is ambiguous. Does it mean "I am allowed to go to the concert" or does it mean "I might go to the concert"?)
When you have a situation like this, use "might" (or a version of "allow") to eliminate the ambiguity.

For example:
  • I might go to the concert. correct tick
  • I am allowed to go to the concert. correct tick

Use "Might" in the Past Tense

Nowadays, you can safely use "might have" and "may have" interchangeably. However, be aware that some strict grammarians might insist that only "might have" can be used in the past tense. Therefore, to play it safe, you should opt for "might have" over "may have."

For example:
  • I might have cooked a lasagne if you hadn't called. correct tick
  • I may have cooked a lasagne if you hadn't called. correct tick
  • (This is not wrong, but it does not sound as natural to the native ear as the "might have" version. This is especially true when the event did not occur. In this example, the lasagne did not get made.)
For most native English speakers, "might have" usually sounds better. However, if you have a good reason for using "may have" over "might have," you should go for it.

For example:
  • The mites may have caused the infection. correct tick
  • (In this example, the author was keen to avoid "mites might.")

They're Auxiliary (or Helping) Verbs

"Might" and "may" are classified as modal auxiliary verbs (also called "helping verbs." ("Can," "have," "would," "should," and "could" are also modal auxiliary verbs.) A helping verb accompanies another verb in order to help express its tense or mood.

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