The verb may is one of the oldest in English. Through the centuries, it has been used with a variety of meanings that need not trouble modern English speakers. Only two forms survive: may and might. The words are often used interchangeably, but a few distinctions still matter
Mother, May I?
I’m old enough to have been brought up to distinguish between may and can. Back then, mothers, teachers, and even school secretaries were quick to challenge the child who asked, “Can I” instead of “May I?” We were reminded again and again that Can I? means “am I able to?” and May I? means “do I have permission to?”
Fact and uncertainty
When it comes to may and might, the words are often used interchangeably in speaking, but there are differences to consider in writing.
The use of may indicates that something is factual or could be factual.
I may have left my keys in the car. (I’m sometimes forgetful.)
They may not have intended to insult me. (They are well intentioned people.)
The invitation may have been lost in the mail. (The mail is often delayed.)
My brother may lend us his car to go to the mall. (He’s very accommodating.)
The use of might in the same sentences could change the notion of factual possibility to a suggestion of doubt.
I might have left my keys in the car. (but I’m not that absent-minded!)
They might not have intended to insult me. (but they knew what they were saying!)
The invitation might have been lost in the mail. (they probably never sent one!)
My brother might lend us his car to go to the mall. (when pigs fly!)
Use might when the thought is hypothetical, uncertain, or contrary to fact.
If he’d had loving parents, he might have developed a more positive character.
If Keats had lived longer, he might have published more than fifty-four poems.
If John Adams had paid attention to his wife, the Constitution might have been a very different document.
When it doesn’t matter
Generally speaking, when speculating about the future, one may safely choose either may or might.
Paul Brians (Common Errors in English Usage) observes that might suggests “a somewhat lower probability” than may:
You’re more likely to get wet if the forecaster says it may rain than if she says it might rain, but substituting one for the other is unlikely to get you into trouble—so long as you stay in the present tense.
When it does matter
Consider the following sentence from a recent New York Times article:
John F. Kelly, the White House chief of staff, tried to stop classified documents from being taken out of the Oval Office and brought up to the residence because he was concerned about what Mr. Trump may do with them and how that may jeopardize national security.—New York Times, 10 February 2022.
Because the paragraph is written in past tense, might is called for. If the article had appeared in 2020, most readers would likely have passed over the may without noticing. In 2022, the incongruity of present tense may for something that is presumably no longer possible is jarring. The sentence demands might do and might jeopardize.
Speaking vs Writing
Choosing between may and might in ordinary informal speech is a minor problem, if a problem at all. In written expression, on the other hand, the choice between may and might often matters.