might have done vs possibly has done vs yesterday

[Alexey86]

- Who has broken the window? Any suggestions?
- I'm not sure, but
a) he might have done it.
b) he has possibly done it.

- When did he do that? Any suggestions?
- I'm not sure, but
c) he might have done it yesterday.
d) he possibly has done did it yesterday.

Why does might + have done allow for a specific time? I know all modals + have done can take a specific time, but I just want to focus on might.

This is more of a theoretical question than a practical one. That's why I put it here.

[PaulMatthews]

The present perfect is a compound tense combining past and present. The significance of the present tense component can be seen in a couple of ways, one of which is that the present perfect often allows time adjuncts referring to the present, but it more or less excludes time adjuncts referring to the past (like "yesterday") since they divorce the situation from present time

Note that the same kind of restriction applies to the past perfect, in that it does not normally allow time adjuncts referring to the present.

[Tarheel]

The present perfect is a compound tense combining past and present. The significance of the present tense component can be seen in a couple of ways, one of which is that the present perfect often allows time adjuncts referring to the present, but it more or less excludes time adjuncts referring to the past (like "yesterday") since they divorce the situation from present time

Note that the same kind of restriction applies to the past perfect, in that it does not normally allow time adjuncts referring to the present.

One of the best explanations i've seen.

[Alexey86]

One of the best explanations i've seen.

I agree, that's a very clear explanation, but... how does it answer my question? Maybe I'm missing something. It's clear why I have done it yesterday is wrong. But why does it become correct when we put might before have done? Or, I can reword my question: If might strongly refers to the past, which explains the correctness of yesterday, why does it allow for the present perfect, e.i. have done?

the present perfect often allows time adjuncts referring to the present, but it more or less excludes time adjuncts referring to the past (like "yesterday")

What do you mean by 'more or less'?

[Tarheel]

Sorry I can't be more helpful. (I forget more grammar every day. Plus my eyes have been watering, which makes it hard to see.)

[PaulMatthews]

The present and past perfect constructions have compound tense, but in He might have done it yesterday, "have" is in the plain form so there is no primary tense, no compound tense, meaning that past time adjuncts are admissible.

[Alexey86]

Might have done is not a present perfect form; it is a modal perfect form. It is used with reference to past-time situations.

- Why is he sad?
- a) He might have got some bad news.
- b) He has possibly got some bad news.

Is there any difference between a) and b) in terms of time reference?

[PaulMatthews]

- Why is he sad?
- a) He might have got some bad news.
- b) He has possibly got some bad news.

Is there any difference between a) and b) in terms of time reference?

You're drifting away from your original question which centred around the perfect.

"Have got" is an idiom, not the present perfect of "get".

[Alexey86]

You're drifting away from your original question which centred around the perfect.

"Have got" is an idiom, not the present perfect of "get".

- Why is he sad?
- He might have lost the game.
- He has possibly lost the game.

[PaulMatthews]

- Why is he sad?
- He might have lost the game.
- He has possibly lost the game.

We've covered a fair bit of the ground in connection with the perfect tense, at least as far as time adjuncts are concerned.

What do you think is the answer here (where there are no time adjuncts), bearing in mind what we said about "might" and the perfect tense?