Descartes' dualism argues that mind and body are fundamentally distinct substances. The mind is an immaterial, thinking thing, independent of the physical body. The will, therefore, is inherently free and unconstrained, operating as the source of human freedom.
On the other hand, many contemporary philosophers hold that there is no immaterial soul or will, and therefore no Cartesian free will. Additionally, many contemporary neuroscientists, such as Robert Sapolsky, argue that any capacity for free choice is limited by prior biological factors, including neural activation, genetics, and the environment. Some suggest a compatibilist view. Biology may indicate there is no objective free will, but Daniel Dennett claims free will is real "to us" in the same sense that colors are real "to us." There may not be colors objectively, but we function in a world of real colors. We stop at a red light, enjoy a blue sky, and follow a hiking trail marked by colors. In the same sense, we hold people responsible for their actions. Regardless of biological evidence against free will, you get a ticket for speeding and go to jail for murder. For us, free will is real and necessary.
Compatibilist free will defines freedom as the ability to act in accordance with one's desires, motives, and intentions without external coercion or impediment, even if those desires are determined by prior events.
Jerry Coyne has a problem with that definition of free will. Dennett is not a Cartesian dualist in that there is a will or mind separate from the brain that can make independent choices. Dennett and compatibilists have redefined traditional free will to make it compatible with determinism. Coyne argues that the compatibilist view of free will is not what the average person thinks of as free will. When compatibilists say free will exists, it misleads people into thinking they have traditional dualist free will.
Dennett defends his view of free will, and Coyne disagrees with his position:
https://www.youtube.com/watch?v=wF-MJcw7QnA&list=PLrxfgDEc2NxZiPzRjCs0Ai6DwM49xshC-
https://www.youtube.com/watch?v=CiZAlG-BhwA&list=PLrxfgDEc2NxZiPzRjCs0Ai6DwM49xshC-&index=3