"May" & "Might": What's the right context?
- I may not be coming in tomorrow...
- I might not be coming in tomorrow...
When should I use "may" and when should I use "might"?
Solution 1:
Formally, might is the past tense of may. In situations where the past tense is required, only might may be used:
Correct:
He said he might go.
Subordinate clauses in English must be in the past tense if the main clause is in the past tense, so this is correct.
Incorrect:
He said he may go.
Here you cannot use the present tense may with the past tense main verb said.
However, in the present tense may and might can be used interchangeably, meaning that all of the following are correct:
He says he may go.
He says he might go.
He may go.
He might go.
Solution 2:
Might is also the past subjunctive of may. Because of this, in some cases these aren't interchangeable; if you're using the subjunctive to form a feeling of conditionality, may is rather inappropriate. For example, "If you were the King, then you might be able to do that."
In the same way, you can use might to form more polite questions: "Might I join you?" as opposed to "May I join you?"
Solution 3:
may
We can use 'may' to ask for permission. However this is rather formal and not used very often in modern spoken English. We use 'may' to suggest something is possible
might
We use 'might' to suggest a small possibility of something. Often we read that 'might' suggests a smaller possibility that 'may', there is in fact little difference and 'might is more usual than 'may' in spoken English.
more..
Solution 4:
In the present tense, they are interchangeable, though there is a subtle difference implied in the likelihood of the thing happening (you coming in tomorrow, in this case):
Most of the time “might” and “may” are almost interchangeable, with “might” suggesting a somewhat lower probability. 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. (source)
Solution 5:
When could I use May and might?
Ia. Some people follow the rule that may can be considered a greater possibility than might.
“They both indicate that something is possible, but something that may happen is more likely than something that might happen.” Quick and Dirty Tips
“’May’ simply states the possibility or likelihood, while ‘might’ emphasizes the conditional nature of the possibility, introducing a greater level of uncertainty.” After Deadline NYT
Ib. However, in practice most people use may and might interchangeably in most cases.
“Often we read that might suggests a smaller possibility that may, there is in fact little difference and might is more usual than may in spoken English.” English Grammar secrets
IIa. May can be considered permission
Example: “Mother may I visit my friend?
"You may.”
II b. It is recommended to prefer might not over may not for clarity because may can be considered "permission"
According to Garner’s Modern American Usage (a bible for all grammar nuts like me), you should never use “may” in a negative hypothetical because the reader could read it to mean the person “does not have permission.” For example, saying “I may not go to the store” could be misread as “I am not allowed to go to the store.” In this case, you always use “might”: I might not go to the store.
Writer's Digest
III. It is recommended to prefer might have over may have for a hypothetical that didn’t happen
Example: when using “may have” and “might have” you can use either if the truth of a situation is still unknown (i.e. "I think your comment may have / might have offended some people"), but if the truth of the situation is known and you are speaking about a hypothetical alternative that did not occur, it’s clearer and more common to use “might have” (i.e. "If Brazil’s best player hadn’t been hurt, they might have won the World Cup").
IVa. Historically different tenses:
In historical practice for the usage of these words some people used “may” exclusively for present tense and “might” exclusively for past tense Oxford Dictionaries
IVb. Modal usage most commmon today
Today the words may and might are used as modals like would, should and could, meaning that they are generally used without regard to their historical tense and the modal used should reflect a slightly different meaning.
IVc. Even today, especially for some situations involving past tense, many people feel might is still not always interchangeable with may in normal usage.
For instance, because it sounds awkward to mix past tense and present tense, many people including myself would probably prefer “after I read that book, I knew I might visit London one day” to using 'may' (but if someone did use 'may' I could live with it, just wouldn't prefer it).
On the other hand, I find “Last night the weatherman said it may rain today” acceptable, especially because whether it will rain is something that is still an unknown.