"May I go to the bathroom?" and "I asked if I might go to the bathroom."

The modal auxiliary 'may/might' is used to ask permission.

"He may not have understood your question." and "He might not have understood your question."

The same modal auxiliary is used for uncertainty.


  • We don't have enough modals. In particular, English does not have a modal that is set aside for permission, and so we have appropriated can and may for that purpose. German has dürfen set aside for this purpose. However, the English cognate of dürfen, tharf, came to mean need, and was replaced by the modal need in Middle English. Feb 4, 2014 at 21:44
  • @PeterShor It might be argued that we have plenty of modals (particularly with the new periphrastic ones), but what we sadly lack is inflections for mood. Not that we're going to invent them any time soon, having spent most of the last 800 or a thousand years getting rid of them. Feb 4, 2014 at 22:38
  • @Stoney: The periphrastic modal "be allowed to" conveys the desired meaning without ambiguity, but everybody uses "can" and "may" anyway. The OP asked why we use the same modal to ask permission and for uncertainty; my answer is that we don't have enough nonperiphrastic modals (German doesn't either, but the modal that is missing is the one for uncertainty). Feb 4, 2014 at 22:49
  • @PeterShor - True - though where I come from there was a lot of Lemme? Feb 4, 2014 at 23:16

4 Answers 4


According to OED 1, the oldest meaning (attested from the early 9th century) was “to be strong, have power or influence”—a sense still present in the noun might and the adjective mighty.

No later than the end of the 9th century the word was in use to express “objective possibility, opportunity, or absence of prohibitive conditions”.

The permissive sense developed somewhat later, around the year 1000: “To be allowed (to do something) by authority, rule, law, morality, reason, etc.”. This is a fairly obvious extension of the primary sense: to permit someone to do something is to grant them the “power” to do it.

What you describe as the “uncertainty” is attested by 1200. Again, it's a logical step: to say you are able to do something is different from saying you will do it, so may cedes ‘ability’ to can and assumes the sense of “Expressing subjective possibility, i.e. the admissibility of a supposition”.


Originally, might / may meant having the ability to do so. The noun might as in strength comes from the same root. This differed from the similar rôle of could / can in that originally might referred to power, could to knowledge.

From this origin, we have both the meanings you suggest.

That of uncertainty relates to possibility. It is true that I might have misread your question and be writing a useless answer, it is not true that I might grow wings and fly before I finish this sentence. I have the ability to do one, but not the other, but my saying I might do so does not mean that I will.

That of permission also relates to possibility; someone has the authority to permit or deny something (or perhaps in some circumstances we may cede them that authority before asking their leave, out of politeness), and hence it is they who we must ask if we may / might do something.

  • Oh, bother, you got there first! Feb 4, 2014 at 21:47
  • @StoneyB, you get a +1 from me anyway, for including the dates I'd decided to leave out.
    – Jon Hanna
    Feb 4, 2014 at 22:33
  • Well, old farts like me enjoy history that's substantially older than we are. Feb 4, 2014 at 22:50

I'm afraid it's one of those features of the English language that you just have to accept without question or pause. Similarly, the modal "can" also has different functions (ability, permission). In fact, I'd say most, if not all, modals have many functions.

  • 1
    The English language has no such features. It has a few cases where questioning won't bring an answer (this is not an example of that), but none where questioning isn't worth doing. If nothing else, one tends to find interesting answers to questions one didn't have, in the endeavour.
    – Jon Hanna
    Feb 4, 2014 at 21:39

Etymologically, 'may/might' are linked to the idea of 'power', 'Macht' in German.

So asking for permission is ackowledging that someone has power over you.

That is why in our present world, which prides itself on having become more egalitarian than ever before, people prefer not to use 'may/might' when they are asking permission. It is felt as humbling – if not humiliating – oneself.

Instead, 'can/could', which come from the idea of 'know-how', 'kennen' in German, are used.

"Can I go to the bathroom?" is asking whether the objective conditions for my going to the bathroom are met… which is a bit blunt! The listener has been stripped of his or her authority almost entirely.

Putting 'can' in the conditional – "Could I go to the bathroom?" – does the trick of preserving both the speaker and the listener's dignity (*dignities?).

So, saying something 'may/might happen/have happened', dates back to a – religious – time when an ultimate authority granting or refusing permission for an event to happen was ackowledged: God's.

The uncertainty of the future was still felt as being to do with permission, hence the same modal auxiliary.

Se non è vero, (è ben trovato)!

  • If you feel the need to avoid "may" out of political feeling, why ask if you "can", unless you're unsure if it's possible. "Excuse me, I'm just going to the toilet" would serve, and be normal enough in more egalitarian conditions. If you really felt moved by ideological zeal, you could omit the "excuse me". The bit about God doesn't stand up; if one suggests, for example, that a table looks like it might break, you are speaking of the capacity of the table, not of the divine.
    – Jon Hanna
    Feb 4, 2014 at 22:16
  • How about Inch Allah?! Do you think Christians never were fatalistic?
    – user58319
    Feb 4, 2014 at 22:25
  • They often have been, though not often to the extent that Inch'Allah speaks of. This has left a mark on the language, but not here; it's mark is seen in expressions about what their God might will, not about what others might.
    – Jon Hanna
    Feb 4, 2014 at 22:31
  • If you are asked permission by someone who uses 'May I?' you are more likely – not being a royal and not feeling like one – to answer with 'Yes, you can' or 'No, you can't' than 'Yes, you may.' or 'No, you may not.' Isn't this a way of making the person who knelt before you stand up again, doing away with feudalism?
    – user58319
    Feb 4, 2014 at 22:40
  • This 'democratic' interpretation of the decline of deontic may was I think first advanced in the 90s, and has been seized upon by many otherwise sober linguists, but I've never seen a scrap of evidence. It certainly does nothing to explain the disappearance of present-tense mote, and the decline of epistemic shall and dynamic will, which seem to me to be parallel developments within the same system for which parallel 'explanations' should be sought. Feb 4, 2014 at 22:47

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