The Problem With Saying That Free Will Is an Illusion
I recently finished watching Bodies on Netflix and the concept of free will comes up a fair bit given that the show involves a predestination paradox. One of the characters voices the opinion that, in his words, "free will is an illusion" because human choices are ultimately the result of physics and biology. Humans choices, in other words, are predetermined, and that means that the free will doesn't exist.
The character in question is acting as a mouthpiece for the notion of incompatibilism, the idea that free will and determinism are mutually exclusive concepts. It's the most common way that the free will debate is framed. If you accept the idea of incompatibilism, then you can either believe in determinism (usually considered the rational choice) or you can believe in free will (usually considered the irrational or emotional choice). But you can't believe in both. The character, being a scientist, believes in determinism, hence his assertion that free will is an illusion.