Nominull: I believe Eliezer would rather be called Eliezer...

Ian C.: We observe a lack of predictability at the quantum level. Do quarks have a free will? (Yup a shameless rip-off of Dougs argument, tee-hee! =) Btw. I don't think you can name any observations that strongly indicate (much less prove, which is essentially impossible anyway) that people have any kind of "free will" that contradicts causality-plus-randomness at the physical level.