[Grammar] couldn't vs can't

[NAL123]

We normally say that the modal verb "could" is less confident/more hesitant than the modal verb "can". But what about the "negative could"; i,e, "couldn't or could never"?

Consider these sentences of mine, please:

a) That can't be true.

b) That couldn't be true. (not talking about the past)

Which one of a) and b) is more confident?

c) I can never forget you.

d) I could never forget you. (not talking about the past)

Which one of c) and d) is more confident?

 

[GoesStation]

A and B are equal to me. It's hard to think of a context where I'd use C. D is natural.

 

[jutfrank]

We normally say that the modal verb "could" is less confident/more hesitant than the modal verb "can".

No, we don't. That's not a great way of trying to understand this.

Also, your examples are no good because it's not clear what they are supposed to mean. Only a) is useful in any way as an example, in my opinion. Note also that sentence a) is not really about the past, if that's what you meant to imply.

 

[NAL123]

Note also that sentence a) is not really about the past, if that's what you meant to imply.

a) and b) are supposed to be talking about the present and c) and d) about the future.

 

[jutfrank]

a) and b) are supposed to be talking about the present and c) and d) about the future.

I'm guessing you mean this, then:

It can't be true. [present]

This could be either a statement about the logical impossibilty of something or an exclamation of despair about recently heard bad news.

I'll never forget you. [future]

This could be said to someone on seeing them for the last time.