Even in a fully deterministic dynamic system, if you have enough variables that are irreducible, you will be unable to predict future states of the system because the rate of change of the system will outpace the rate of computation/modeling of that system. Therefore, you can have a situation where you have a complete lack of free will (a complete lack of randomness), down to the particle level, but at the same time, maintain the illusion of randomness and/or choice.