You know the kind of thing where you know what’s grammatically right but you don’t know the rule? And people do it wrong and you flinch but you can’t explain WHY they’re wrong, you just know they are? For me that feeds into occasionally telling a student, “I can’t explain it, but I’m right, do it my way.” But then you’re all like, WHAT IS THE DAMN RULE ANYWAY?
Well, I finally looked up the difference between “may” and “might”, and, let me tell you, there are a lot of different opinions about this, way more than about any other grammatical thing I’ve ever looked up. I mean, the difference between “who” and “whom” is simple — subject vs object — and even the difference between “which” and “that” is relatively simple — nonrestrictive vs restrictive clauses — and at least everybody agrees. But people are all over the place when it comes to “may” vs “might.”
Some grammar websites insist the two words are nearly interchangeable except that “might” suggests a somewhat lower probability than “may,” but that can’t be right because way too often when I’m reading, I stumble over “may” when I know, I KNOW, that it should be “might.” It wouldn’t feel so wrong if the only difference was a perception of lower probability.
Other websites say that “might” is the past tense of “may”, so that you say “He might have been eaten by the dragon” rather than “He may have been eaten by the dragon,” but that can’t be right either, because I can easily put either of those sentences in a context where it would sound right, like so:
“Gavin hasn’t come in this morning; I’m afraid he might have been eaten by a dragon.”
“Well, yeah, Gavin may have been eaten by a dragon, but you know that won’t stop him — he’ll come back as a ghost in a day or two, so we have to be prepared to face him again!”
Do those sentences sound right to you? I actually think that I could read both of them with either the “may” or “might” and all the versions sound okay to me — definitely not wrong enough to make me stumble if I were reading a story got one of these stentences.
Finally I visited my favorite grammar website, which neatly encapsulated another difference:
Avoid confusing the sense of possibility in may with the implication of might that a hypothetical situation has not in fact occurred.
And I think this is the one that writers often get wrong. In the first dragon sentence above, Gavin might have or may have been eaten by the dragon. Either would work because you are expressing a possibility, and I suppose “might” could express your opinion that the possibility is not very likely, but I don’t think even very sensitive readers would stumble over either version.
But try this sentence:
“Gavin might have been eaten by the dragon, but it turns out he dodged past and successfully made it into the wizard’s castle.”
In this case, you couldn’t use “may” because you are talking about a hypothetical possibility that didn’t happen. If you used “may,” sensitive writers would stumble.
I *think* this is the most common situation where I feel the wrongness of “may.” I am certain that it’s always “may” that is the problem, never “might.”
So I guess if you try to boil it down, it’s more or less like this:
“Might” sometimes is used to express a low probability — lower than “may” — but this is subtle and doesn’t matter much.
“Might” is usually the past tense of “may” and in general you want “might have,” not “may have.”
“Might” is used to indicate that something that might have happened, didn’t.
Or something like that.