The gentle reader should be aware that I arrived at his conclusion, that there is no such thing as free will, for the same reasons as Harris some time ago. So, readers may decide that I am too easily convinced by his arguments. Long time readers of my blog will recall I was very critical of The Moral Landscape, which I thought was deeply flawed, so it's not that I'm somehow under his spell. I just have to admit that he nailed this issue.
All of our thoughts arise in us from unconscious processes. We don't control the thoughts that arise, they just arise. We don't control our desires or intentions; they just happen to us. Even if we have a soul we did not choose it; wicked people under this theory are simply unfortunate. Even if conscious processes are necessary for certain decisions, we are passive recipients of those processes.
Quantum Uncertainty is no solution. It just makes our decisions statistical, not free.
He recounts the now famous Libet experiments that show that our decisions can be predicted by brain states before we are consciously aware of these decisions.
If you believe in free will I recommend this short, well-argued book as a challenge to your thinking. I think he is convincing, but that's just me.
He also takes on the notion that without free-will we will not do anything. Clearly some things in life require we make a conscious decision. We can't not make decisions in this life; but we are passive recipients of the decisions, not entities that somehow 'control' them. The whole line of thought is not even coherent.
He successfully fends off Daniel Dennett and the other compatibilists. Again, I think he does a better job than I can do here in this post.
So, my congratulations to Sam Harris for writing such a good book! Not that he's worried what I think...