As I understand it as a layman who uses GPT4 quite a lot to generate code and formulas, it doesn’t understand logic at all. Afaik, there is currently no rational process which considers whether what it’s about to say makes sense and is correct.
It just sort of bullshits it’s way to an answer based on whether words seem likely according to its model.
That’s why you can point it in the right direction and it will sometimes appear to apply reasoning and correct itself. But you can just as easily point it in the wrong direction and it will do that just as confidently too.