The very question of "could that act have been freely willed or determined" is itself a demonstration of free will. What is absurd is the idea that evolution would determine a human to falsely think they have free will. There is no advantage to that in terms of evolutionary survival, in fact the opposite would be the case. We believe we have free will as a result of our awareness of the reality of our consciousness.

https://medium.com/inserting-philosophy/william-jamess-argument-for-free-will-4b581138a765