How to disprove free will using basic logic

[IIIIITHE1IIIII]

Madn said:

It's your idea that everything is determined, so our conversation isn't the fruit of our free will.

There's nothing we can do about it, it'already been determined.

I know (well, I can't know for certain, but I do think so), but you don't. And neither does everyone (or even close to the majority) in this thread.