[Grammar] I could not go to Gene's party tomorrow.

[beachboy]

I came up with this scenario myself:

- Hey, beachboy, what time will you be at Gene's party tomorrow?
- 1) Actually, I may not go to the party. I'll let you know later.
- 2) Actually, I might not go to the party. I'll let you know later.
- 3) Actually, I could not go to the party. I'll let you know later.

Do sentences 1, 2 and 3 work in this scenario? I'm not sure about 3.

 

[Tarheel]

I would use #2.

The first one makes it seem like you don't have permission to go to the party.

The sentences in #3 don't go together.

 

[GoesStation]

To me, one and two are similar. Number three doesn't make sense.

 

[teechar]

- 3) Actually, I [STRIKE]could not[/STRIKE] can't go to the party. I'll [STRIKE]let you know[/STRIKE] explain later.

That can work.

 

[beachboy]

In this scenario, I meant that not going to the party was a possibility. I wanted to know if could not can convey the same idea as may not and might not. As I see, it can't.

 

[jutfrank]

No, it can't.

However, it could be meant to express a different kind of possibility. You could imagine someone toying with the idea of not going as a suggested possible solution to a problem, for example:

A: Will you babysist for me tomorrow night?
B: Sorry, I'm going to Gene's party.
A: Oh, no, I was really hoping you would.
B: Well, I suppose I could not go. I'll let you know tomorrow.

Notice that a), I've elided the preposition phrase in the final line, and b)the two sentences there are not very coherent, but the response is possible.