When Sam Harris talks of free will being an illusion, he is not referring to the idea that our minds are subject to the laws of physics (either mechanistic laws or laws involving randomness). He is referring to a basic, and easily verifiable, Buddhist principle. It is easy to prove to yourself that you have no free will by trying to meditate (you do not have to be good at it). Sit calmly and try to think only about the flow of your breath. Your attention will soon stray and various other thoughts will pop into your mind, unbidden. It will be apparent to you that you do not have any control over these stray thoughts. It is in this sense that Harris says you have no free will: you do not have any control over your own thoughts; they enter your mind unbidden. Many people find it profound when they realize (through direct introspective experience) that they are not the authors of their own thoughts.
