Might and may are part of a special set of verbs known as modal auxiliary verbs, which means that they’re used together with other verbs to talk about permission, possibility, suggestions, etc. Over the years, the usage recommendations regarding might and may have become more flexible, but there are still points which you should be aware of, especially if you’re writing or speaking in formal situations.
Here are some very useful guidelines to the main issues from Oxford Dictionary Words Blog.
The verb may is used in five main ways:
- to talk about a possible situation: Those reports may prove to be false.
- to politely ask for permission to do something: May we come in?
- to politely give someone permission to do something: That’s all for now, you may go.
- to admit that something is the case before stating a contrasting fact: The chorus may look silly, but they sound wonderful.
- to express a wish or hope: May they be very happy in the future.
Basically, might is the past tense of may. It therefore seems logical for grammatical sticklers to argue that if you’re talking about a possible situation in the present or the future, you should always use the present tense, may:
If you’re feeling queasy, you may eat less and lose weight.
And, equally, if you’re referring to something which could have been the case in the past, the past tense, might, is said to be correct:
For all we know, she might have been undergoing counselling.
However, people don’t often make this distinction in today’s English, and it’s generally acceptable to use either may and might to talk about the present/future or the past:
- Present or future event
√ She thinks she may be going crazy.
√ She thinks she might be going crazy.
- Past event
√ I might have forgotten to mention it at the time.
√ I may have forgotten to mention it at the time.
Distinctions between may and might
So the general rule is that may and might are usually interchangeable when talking about possible situations. However, there are a few differences in usage between may and might and it’s useful, especially if you’re writing for school, college, or work, to know when each is more appropriate.
1. May have versus might have
If you don’t know the truth about a possible past situation at the time of speaking or writing, you can use may have or might have:
√ I think that comment may have offended some people.
√ I think that comment might have offended some people.
If you’re referring to a possibility in the past but you know that it didn’t actually happen, it’s preferable to use might have:
√ Rose assured us that she was well, but she might have been badly hurt.
X Rose assured us that she was well, but she may have been badly hurt.
2. Degrees of possibility
Some authorities on English usage state that it’s better to use may when you think the chances of something being the case are likely and to use might when it is unlikely (though in practice, this distinction isn’t always clear-cut):
They may visit Ireland in the near future.
[The speaker believes that there’s a fairly good chance that they may go to Ireland]
The woman looked as if she might have been in her late 40s.
[The speaker wasn't very sure about the woman’s age, but made a tentative guess]
If I were Dutch I might see immigration differently.
[I’m not Dutch, I’m an American talking about a theoretical situation]
If you go to bed earlier, you might feel better tomorrow.
[I think that perhaps you would feel better if you went to bed earlier]
3. Reported speech
You should change may into might when reporting past direct speech (what someone has said):
“I may go out of business”. [her actual words]
She said she might go out of business. [reported speech]
4. To show annoyance
If you want to express annoyance or criticism because someone could or should have done something that they* didn’t do, you should always use might rather than may:
√ You might have told me that she wouldn’t be in today!
X You may have told me that she wouldn’t be in today!
√ You’d think they might be able to understand each other’s point of view a bit more.
X You’d think they may be able to understand each other’s point of view a bit more.
5. Polite requests and suggestions
When politely or formally making a request, asking for information, or making a suggestion, might is regarded as preferable to may:
Don’t you think you might be a little old for him?
Might I ask the Court to glance briefly at the judgment of Sir Harry Gibbs?
6. Expressing a wish or hope
If you want to express a wish or hope, then may is always the correct word to use:
√ May you both be very happy.
X Might you both be very happy.
7. Asking for and giving permission
When politely asking for permission to do something, it’s acceptable to use mayor might, but nowadays might is regarded as very formal. May is considered more polite than the most typical way of asking permission in English, usingcan:
May I borrow your pen? [polite]
Might I borrow your pen? [polite and very formal]
Can I borrow your pen? [less polite; considered by some to be incorrect usage**]
When giving (or refusing) permission, only may and can are acceptable:
√ Yes, you may (borrow my pen). [polite]
√ Yes, you can (borrow my pen). [less polite]
X Yes, you might (borrow my pen).
√ No, you may not (borrow my pen). [polite]
√ No, you can’t (borrow my pen). [less polite]
X No, you might not (borrow my pen).