On Determinism  By Sean Carroll | December 5, 2011 10:19 am
Back in 1814, Pierre-Simon Laplace was mulling over the
implications of Newtonian mechanics, and realized something
profound. If there were a vast intelligence — since dubbed
Laplace’s Demon — that knew the exact state of the universe at
any one moment, and knew all the laws of physics, and had
arbitrarily large computational capacity, it could both predict
the future and reconstruct the past with perfect accuracy. While
this is a straightforward consequence of Newton’s theory, it
seems to conflict with our intuitive notion of free will. Even
if there is no such demon, presumably there is some particular
state of the universe, which implies that the future is fixed by
the present. What room, then, for free choice? What’s surprising
is that we still don’t have a consensus answer to this question.
Subsequent developments, most relevantly in the probabilistic
nature of predictions in quantum mechanics, have muddied the
waters more than clarifying them.