Pierre Simon Laplace supposed that everything is composes of atoms and that the motions of atoms are governed by the laws that Isaac Newton discovered in the 17th century. Laplace imagined a super intelligent and mathematically gifted demon, who knows the positions and velocities of all particles in the universe at a particular time, along with all the laws of nature. He claimed that this demon could compute the positions and velocities of all particles at every other time. The demon then could PREDICTE where you body would be and how it would be moving next year from your history and the history of time. Basically he was saying that Newton's laws were deterministic or you could predict the future based on his laws.
Interesting, but what does that mean, really? What it means is that you future is already determined. "I knew you were going to say that!" you would say. If the motions of every atom in your body have been determined when God set everything in motion way back when; then you have no control over your movements, they have been predetermined. Laplace then stated that ether Newton's deterministic laws are false or Free Will is an illusion.
Many philosophers have battled with this paradox of free will vs. determinism and many have made good attempts at resolving it in some form of free will within the confines of determinism but the conflict is still there. Today philosopher/physicists believe that Newton's laws are probabilities and not absolutes. In other words, these laws work MOST of the time the rest of the time Quantum laws take effect. But it would be wrong to say that Quantum mechanics is not deterministic simply because we haven't figured it out yet.
I said all that to say this: Does free will exist? If not, can we have things like justice and morals? Is everything pre-determined for us? If not, what do we do with the laws we keep discovering? This paradox of free will vs. determinism is a VERY biblical battle as well and it has split churches.
The problem with a seemingly irresolvable conflict or paradox is that we tend to throw our hands up in despair and give up. I mean, if all the smart people can't figure it out, how can we? But remember: the growth doesn't happen in reaching the answer, the growth happens in the struggle to get there. Let's struggle together.