May and might are two modals that share certain functions, but with important nuances. Might is not simply the "past form" of may. These two modals each have their own present-tense functions, and might mainly serves to soften and mitigate what may expresses more directly. These two modals primarily express:
- Permission (giving, asking, refusing)
- Probability (equiprobability, uncertainty)
- Politeness (suggestions, softened reproaches)
Welcome to the world of may and might — where permission and probability blend with delicacy.
MAY: Permission and Equiprobability
1. Giving permission
The speaker authorizes the subject to do something.
- You may use the restroom on the left.
This is more formal than can. It's used in official or polite contexts.
2. Asking for permission
The speaker asks for permission from their interlocutor in a question.
- May I borrow your pen, please?
This is very polite, more formal than can I.
3. Refusing permission (prohibition)
With negation, may not gives a prohibition.
- You may not eat in the library.
This is a firm prohibition, but polite and formal.
4. Equiprobability (50/50)
The speaker thinks there's a 50% chance the event is true.
- The package may (or may not) show up on time depending on the traffic.
The recurring expression may or may not emphasizes this balanced uncertainty.
MIGHT: Mitigation, Politeness, and Reduced Probability
Might functions as a mitigated and polite version of may. It softens requests, suggests delicately, and expresses slightly reduced probability.
1. Ultra-polite request for permission
Much more polite and formal than may I.
- Might I use your phone?
Very formal, almost archaic in everyday English. You'll hear this in very polite contexts or period novels.
2. Polite suggestion
- You might like to try the chocolate cake: it's their specialty.
Might softens the suggestion, making it less directive than "you should try."
3. Polite reproach
- The instructions might be a little unclear. Did you have any trouble understanding them?
The reproach is softened by might. It's a polite way of saying "the instructions are unclear."
4. Lack of surprise (retrospective realization)
- I might have guessed you were too busy at the moment.
Expression of a retrospective realization that isn't really surprising.
5. Mitigated equiprobability
Slightly reduced probability:
- He might get there in time, but I can't be sure.
Might is slightly less certain than may. It's a somewhat reduced probability. In reported speech (sequence of tenses):
- She said she might join us for dinner, but she hasn't confirmed yet.
When the main verb is in the past (said), might appears in the subordinate clause through sequence of tenses.
6. Risk (something unfortunate)
- Using expired medicine might have adverse effects on your health.
Might signals a potential risk, something negative that could happen.
Past Permission: COULD or WAS/WERE ALLOWED TO
To express past permission, we use neither may nor might. We use could or was/were allowed to:
- She could use her father's car whenever she needed to.
- She was allowed to use her father's car whenever she needed to.
Past Equiprobability: MAY/MIGHT + HAVE + Past Participle
To express equiprobability about something in the past, we add have followed by the verb in the past participle.
- He may have been feeling overwhelmed, given the stacks of unfinished work on his desk.
- He might have been feeling overwhelmed, given the stacks of unfinished work on his desk.
May have and might have express a past possibility — something that perhaps happened, but we're not certain.
MAY vs MIGHT: Understanding the Difference
MAY is direct and formal:
- Clear, official permission (You may use this)
- Firm prohibition (You may not smoke here)
- Neutral 50/50 equiprobability (It may rain)
MIGHT is mitigated and polite:
- Ultra-polite request (Might I use your phone?)
- Soft suggestion (You might like to try...)
- Softened reproach (You might have told me...)
- Slightly reduced probability (It might rain — a bit less certain than may)
- Potential risk (This might cause problems)
Cases where only MAY works:
- Giving permission: You may enter. (not You might enter.)
- Prohibition: You may not smoke. (not You might not smoke.)
Cases where only MIGHT works:
- Polite suggestion: You might like to consider... (not You may like to consider...)
- Softened reproach: You might have warned me. (not You may have warned me.)
- Risk/danger: This might hurt. (not This may hurt.)
Cases where both work (with nuance):
- Present probability: It may rain (50/50) vs It might rain (slightly less certain)
- Past probability: He may have left vs He might have left (similar nuance)
Conclusion
May and might are modals of permission and probability. May is direct and formal: clear permission, neutral equiprobability. Might is mitigated and polite: soft suggestions, softened reproaches, potential risks, slightly reduced probability. The key difference isn't temporal (past vs present), but tonal: may asserts, might mitigates. Mastering may and might means understanding that English doesn't just say "maybe" — it calibrates the degree of certainty, the level of politeness, and the type of permission with subtle precision.