That just ain't so

[besthost]

"That just ain't so" - what's the meaning of it?

I know ain't = isn't/aren't, but I'm still having a hard time understanding this expression.

"that's just ain't so (what, good, bad?)"

Can you give an exemplary sentence?

 

[oregeezer]

I said "The sun comes up at night."
He said "That just ain't so!"

It is not true.
Or
I do not believe you.

 

[besthost]

Thank you so much.

 

[BobK]

I think 'it just ain't so' started life as an Am English idiom; I first became aware of it in the mid-50s, in the lyrics of the song Cock-eyed Optimist, and I think even now Br English people who use it are either pretending to be American or putting on a show of American-ness for some effect.

b