Could Have

[Volcano1985]

The house could have been very dirty.

Can you explain this sentence? Is it possibility?

[engee30]

The house could have been very dirty.

Can you explain this sentence? Is it possibility?

Yes, it is.
It is possible that the house was very dirty.

[Volcano1985]

"The house might have been dirty" less possibility ?

[engee30]

"The house might have been dirty" less possibility ?

Well, they (may have/might have/could have) mean basically the same. But if you want to put it this way, could have is the least possible of the three.

[Volcano1985]

I was taught could is more possible than may and might.

[svartnik]

could have is the least possible of the three.

Is it not the other way around?

[engee30]

I was taught could is more possible than may and might.

Well, I can't say you were mistaught as far as possibilty is concerned. May and might both say that something is or was possible; but it's could that says that something is or was possible, but not probable. That's why could is at the very bottom of the ladder representing possibility by the use of modal verbs, and that's the way I was taught.

[Clark]

I agree with engee. Would like to add that 'could' here expresses supposition mixed with doubt rather than possibility.

[bhaisahab]

I don't agree because as a sentence 'The house could have been dirty' lacks context, we could say for instance, as a family of hippies had been living there, the house could have been dirty, as it turned out it wasn't.

[Clark]

I don't agree because as a sentence 'The house could have been dirty' lacks context, we could say for instance, as a family of hippies had been living there, the house could have been dirty, as it turned out it wasn't.

Yes, you are right. I overlooked that option. However this is unreal possibility - a hypothetical situation (a situation contradicting reality, to be exact) with past-time reference.