To me, ignorance is lacking knowledge; foolishness is ignoring available knowledge.
Hubby and I have had those "you said this/I said that" "no, you said this, I said that" arguments. As soon as he has clearly repeated the statements correctly, I concede being incorrect. Quickly, too. So quickly sometimes, that he's thought I was just trying to end the argument. Hell no! I'll keep going if I think I'm right, but concede immediately when I see I'm wrong. I've said for years, I'd rather be ignorant than be a fool. One can be remedied, the other is a choice--and choosing to be a fool? No thanks.