Paul says that Eve was honestly deceived into eating the poisonous tree (not really "free will") - and God did not prevent her.
He did, by warning her not to eat it. He did not take away her choice (her free will) to do as she chose, despite his teaching. Also Adam was there. He was not decieved... and he did nothing to try and stop her.
That is a very Jewish view - I personally believe people can have free will without the "proof" of some temptation. The "proof" of free will in human society to me is creativity, social advancement, scientific learning, and so on - not obeying a command from a god or a
snake about a poisonous tree.
Let me make my last statement more clear, lol:
It could have been prevented if free will had NOT been given.
It doesn't really have anything to do with 'proof' of some temptation showing that we are given free will. Just a natural consequence of free will.
Peace,
Tammy