Just because we cannot determine something doesn't mean it's non-deterministic. The question of the existence of free will is very similar – if not equivalent –

Just because we cannot determine something doesn't mean it's non-deterministic. The question of the existence of free will is very similar – if not equivalent – to the existence of real randomness. I.e. a dice roll may be deterministic if you just know the right set of complicated equations for gravity, air resistance, turbulence etc.