[bqe]

Whenever free will comes up I like to bring up Conway's Free Will Theorem[1].

If you define free will as future choices cannot be predicted based on history, then it turns out that if humans have free will, so do elementary particles. To me, this doesn't mean we don't have free will, but instead the linear, deterministic model that's often used to discount free will is just not how the universe works.

Note that this result does not depend on statistical randomness like some of quantum mechanics, but just three simple axioms. I highly recommend reading the full paper, especially the end, "Free Will Versus Determinism".

[1]: http://www.ams.org/notices/200902/rtx090200226p.pdf