[Sethomas]

Well, the Heisenberg uncertainty principle refutes Pierre Simone de Laplace's belief that there could be an intelligence that could predict the future by knowing the present positions and momenta of all particles. As Heisenberg stated, this isn't because the future is notpredetermined (from a quantum standpoint, it is) but because it is impossible to have absolute knowledge of a particle's properties.

Spinster recommended to me a book called The Illusion of Conscious Will by Daniel Wegner, and I enjoyed it muchly. In his final chapter, Wegner stated that the notion of free will is so irrational once you dissect it into its component axioms that virtually no modern theory of psychology dares to incorporate it. In short, he stated that if free will did exist, at most it would be an internal coinflip.