[Grammar] In what way should I distinguish "may have done" from "might have done"?

[xxwzs]

In what way should I distinguish "may have done" from "might have done"?

I am a little confused about the usage of "may have done" and "might have done" when both are used in a speculative situation. Here are some examples:

1. He can't find his schoolbag anywhere. He thinks he ______ it at the library.
A. may have done B. might have done
Note: I have been told that this sentence can work grammatically and logically by filling in the blank with either A or B. Is it true?

2. He could't find his schoolbag anywhere. He thought he ______ it at the library.
A. may have done B. might have done
Note: Students in China are taught that only B can be chosen. Do you agree?

3. Conservationists speculated that a "lake effect" may have caused the birds to mistake the sprawling solar farms for bodies of water. (www.latimes.com Can solar farms and wild places coexist in the American West? 2020/06/02)
Note: For this sentence, can "may have caused" here be replaced by "might have caused"? May I have the reason?

If I have made any inappropriate wording, I am sorry for that.

 

[emsr2d2]

Re: In what way should I distinguish "may have done" from "might have done"?

Neither form works. 'Done' needs to be 'left'.

It is not possible to give a completely satisfactory response about may (have) and might (have). Some people feel that there is a distinct difference in meaning, some see no difference, and some rarely, if ever, use may.

The same goes for Q2, obviously. Did you make up those sentences yourself or did you copy them from a textbook or similar?

 

[Charlie Bernstein]

Re: In what way should I distinguish "may have done" from "might have done"?

I am a little confused about the usage of "may have done" and "might have done" when both are used in a speculative situation. Here are some examples:

1. He can't find his schoolbag anywhere. He thinks he ______ it at the library.
A. may have done B. might have done
Note: I have been told that this sentence can work grammatically and logically by filling in the blank with either A or B. Is it true?

A and be are both grammatical, but neither makes sense.

2. He could't find his schoolbag anywhere. He thought he ______ it at the library.
A. may have done B. might have done

Again, they're grammatical but don't make sense.

Note: Students in China are taught that only B can be chosen. Do you agree?

No. In that context, might and may mean the same thing.

3. Conservationists speculated that a "lake effect" may have caused the birds to mistake the sprawling solar farms for bodies of water. (www.latimes.com Can solar farms and wild places coexist in the American West? 2020/06/02)
Note: For this sentence, can "may have caused" here be replaced by "might have caused"?

Yes.

May I have the reason?

I don't know why (in this context) they mean the same thing. They just do.

My father would have asked: "Might I have the reason?"

If I have made any inappropriate wording, I am sorry for that.

Do you see why those A's and B's don't make sense?

 

[jutfrank]

Re: In what way should I distinguish "may have done" from "might have done"?

If you're looking for a more prescriptive response to your question, here's what I'd teach you:

1) Use may have left. The word may expresses a kind of present possibility.

2) Use might have left. The word might expresses the same kind of possibility but places it in the past.

3) Use may have caused for present possibility, similar to 1.

 

[Charlie Bernstein]

Re: In what way should I distinguish "may have done" from "might have done"?

If you're looking for a more prescriptive response to your question, here's what I'd teach you:

1) Use may have left. The word may expresses a kind of present possibility.

2) Use might have left. The word might expresses the same kind of possibility but places it in the past.

3) Use may have caused for present possibility, similar to 1.

Good to know. American English doesn't have that distinction.

(You should hear us argue about the difference between will and shall!)

 

[GoesStation]

Re: In what way should I distinguish "may have done" from "might have done"?

Good to know. American English doesn't have that distinction.

Mine does, but most speakers no longer make the distinction.

 

[Charlie Bernstein]

Re: In what way should I distinguish "may have done" from "might have done"?

Mine does, but most speakers no longer make the distinction.

That'd be me!

You: Is Annie still here?
Me: I don't know. She might have left.

You: Is Annie still here?
Me: I don't know. She may have left.

Which one do you like?

 

[GoesStation]

Re: In what way should I distinguish "may have done" from "might have done"?

You: Is Annie still here?
Me: I don't know. She might have left.

You: Is Annie still here?
Me: I don't know. She may have left.

Which one do you like?

There's little difference in that context. The following dialogs demonstrate the distinction that I make.

You: Did Annie win the pie-baking contest?
Me (1): I don't know. She may have. Let's check the web site and find out!
Me (2): No. She might have, though, if only she'd followed my suggestion to use chilled bits of butter in the crust!

 

[TheParser]

Re: In what way should I distinguish "may have done" from "might have done"?

NOT A TEACHER

Here is the "rule" that some people try to follow. (The dialog(ues) are only mine.)

Mona: Who won the election yesterday?
Raul: I do not know. It may have been Mr. Jones. But the final results have not come in yet.

Mona: I hear Ms. Smith lost the election last night.
Raul: That's right. Her supporters feel that she might have won if she had smiled a little more. But she rarely smiled during the campaign.


My source: John Honey, Language is Power (1997), pages 158-159. Mr. Honey gives this "crude" rule-of-thumb: "might have been" could have happened but did not;
"may have been" could have happened but we don't know yet.

 

[jutfrank]

Re: In what way should I distinguish "may have done" from "might have done"?

My post #5 was meant very much prescriptively. In reality, it seems to me that British English speakers use may and might pretty much interchangeably to express present possibility. So in sentence 1 in the OP, and in Charlie's 'Annie' example, both may and might are very likely, and both sound very natural to me.

However, when it comes to past possibility, as in sentence 2 in the OP, only might feels right to me. I'd like to ask GS and CB (and any other AmE speakers reading this) if they feel the same way about that one too. Do you think He thought he may have left it at the library sounds okay?

 

[GoesStation]

Re: In what way should I distinguish "may have done" from "might have done"?

I "liked" TheParser's post, but please note that no native speaker would say "do not know" or "have not come in" in a similar dialog. We'd use the contractions don't and haven't.

 

[Charlie Bernstein]

Re: In what way should I distinguish "may have done" from "might have done"?

. . . However, when it comes to past possibility, as in sentence 2 in the OP, only might feels right to me. I'd like to ask GS and CB (and any other AmE speakers reading this) if they feel the same way about that one too. Do you think He thought he may have left it at the library sounds okay?

It does to me, but I come here to learn as much as I do to teach. So — interesting!

 

[jutfrank]

Re: In what way should I distinguish "may have done" from "might have done"?

I was wondering whether He thought he may have left it in the library sounds okay to anyone. Just curious.

[cross-posted]

 

[GoesStation]

Re: In what way should I distinguish "may have done" from "might have done"?

I'd like to ask GS and CB (and any other AmE speakers reading this) if they feel the same way about that one too. Do you think He thought he may have left it at the library sounds okay?

That's a great example of the useful distinction that has largely disappeared in recent years. It sounds wrong to me. I would never say it to express the concern that he had in fact left it there. Nevertheless, I hear that kind of usage all the time.

 

[PaulMatthews]

Re: In what way should I distinguish "may have done" from "might have done"?

I think it all boils down to dialects. Dialects A and B are differentiated by reference to constructions like

1. I thought it might rain before we got home.
2. I thought it may rain before we got home.

In the older Dialect A (which I speak) [2] is ungrammatical (just like *I thought I can finish the book before I got home): [1], with might is required.

In Dialect B, [2] is possible as well as [1]. In Dialect A, might is undoubtedly the preterite counterpart of may, just as could is of can because it is the form required in backshift.

In Dialect B there's no basis for retaining (from earlier stages of the language) the analysis of might as the preterite of may: it must be a distinct lexeme.

One factor facilitating this linguistic change is that might even in Dialect A is hardly used in the primary sense of the preterite, to indicate past time: we usually say was/were allowed rather than might for past time permission, e.g. He told me I/we might go.

 

[Tarheel]

Re: In what way should I distinguish "may have done" from "might have done"?

However, when it comes to past possibility, as in sentence 2 in the OP, only might feels right to me. I'd like to ask GS and CB (and any other AmE speakers reading this) if they feel the same way about that one too. Do you think He thought he may have left it at the library sounds okay?

This American would only use "might" there. (Some of us only use "may" as a formal way of making a request.)

 

[abo.omar]

Re: In what way should I distinguish "may have done" from "might have done"?

As far as I know both may have left and might have left refer to past possibilities.
May have left refers to stronger possibility than might have left 70% to 30%.
is it acceptable?

 

[5jj]

Re: In what way should I distinguish "may have done" from "might have done"?

It might be for some speakers. It's not for others.

 

[Charlie Bernstein]

Re: In what way should I distinguish "may have done" from "might have done"?

As far as I know both may have left and might have left refer to past possibilities.
May have left refers to stronger possibility than might have left 70% to 30%.
is it acceptable?

I don't understand it as a difference in likelihood. They both simply say it's possible that he left. Maybe he did, maybe he didn't. He may have. He might have.

 

[abo.omar]

Re: In what way should I distinguish "may have done" from "might have done"?

I don't understand it as a difference in likelihood. They both simply say it's possible that he left. Maybe he did, maybe he didn't. He may have. He might have.

deductions in the past
Ali must have travelled. That means I am sure 90percent he travlled.
Ali may have travelled. That means I am sure 70 percent he travlled.
Ali might have travelled. That means I am sure 30 percent he travlled.
It is the British native way which I had been taught a long time ago.