I don't rate books 5 stars lightly, but this was exactly the kind of discussion of free will I wanted, at least at this point in my reading. I've read a lot of books about the mind, consciousness and free will and almost all of them spend far more time rehashing philosophy back to Descartes or further back, and then barely say anything at all based on modern scientific understanding. Then I've read books with plenty of modern scientific experiments, but that don't do nearly as good a job of tying those technical details back to higher level ideas with meaning or consequence.

Also, I don't usually read that many reviews of books before I review them, but for this book most of the criticism I read seemed to be that people thought the other was arguing for some particular point or another and they didn't like that. I didn't think the author was trying to argue that there's one right point of view regarding free will, but instead shows us how complex it is to define what free will even is, what different definitions might mean, and how experiments have validated those understandings or not. For example, this book briefly mentions that quantum effects might mean the universe isn't deterministic and could be a way for one interpretation of what free will is to be possible. I've never particularly liked that argument, but I don't think it was being put forth as the only possible solution, instead it's treated as many other ideas regarding free will and the mind and examining each in turn.

If anything the main flaw I see is that so many different points of view are presented it's a little hard to keep a coherent narrative and grouping of ideas going. However, the book is short enough that it's not too hard to follow the tangents.

My favorite part by far is the description of the experiments with split brain patients, which I'd heard about before at a high level, but are very well explained here. Likely because the author conducted many of these experiments himself.

I felt like this book gave me the background to more easily evaluate and succinctly state my own thoughts on free will without forcing me into that opinion. Basically I don't think free will exists the way it's always vaguely alluded to in colloquial use and some philosophical uses, which is basically like a ghost in the machine. If you define free will as basically being able to deterministically and appropriately respond to your surroundings then it seems to exist as an emergent property of complex underlying systems, even though that's a very unsatisfying definition. Even if free will is limited to that, the way we have a part of our brain basically providing a narrative to make it feel as though we're a ghost in the machine is fascinating.