This is a nice little video to express why incompatibilism is the most robust worldview with regard to free will. This means that free will is incompatible with determinism, and that, given determinism, or even near determinism (physical indeterminacy) free will is an illusion.
Pereboom refers to the example Robert Kane (a rare naturalist who also adheres to libertarian free will) gives. Imagine a woman who is caught between two choices. She is walking to work to a meeting with her boss. She sees someone being assaulted in an alleyway. She is 50-50 caught between carrying on to her meeting or helping the guy out. Forget the context of this choice, the idea is that there are no causal reasons making her choose one or the other, hence the 50-50. This leaves the choice fully up to her, the agent, and not in the hands of external factors (since it is the external factors which are concluding to a 50-50).
So the agent is in control. This is what Kant called Transcendental Free Will and is the only freedom that will get us moral responsibility, according to him. This entails causing a decision without that being causally determined. Essentially, origination of a decision / causal chain. Kant said that we have no evidence that we have this causal power; that we can’t even show it but that it doesn’t, supposedly, contradict anything we believe. Er, apart from the philosophical ideals of causality…
Kant, though, saw it as necessary to believe it for moral reasons – it is the only way we can be moral agents and have moral law.
Pereboom disagrees, as you will see in the video. It’s a good, concise video. I would recommend Pereboom’s excellent “Living Without Free Will”. After my book, Free Will?, of course.