The sense that we are unified subjects is a fiction, produced by a multitude of separate processes and structures of which we are not aware and over … - Sam Harris

One thing each of us knows for certain is that reality vastly exceeds our awareness of it.

Am I identical to my skin? If not — and the answer is clearly no — why should the frontier between my outside and my inside be drawn at the skin? If not at the skin, then where does the outside of me stop and the inside of me begin? At my skull? Am I my skull? Am I inside my skull? Let’s say yes for the moment, because we are quickly running out of places to look for me. Where inside my skull might I be? And if I’m up there in my head, how is the rest of me me (let alone the inside of me)?

Free will is actually more than an illusion (or less), in that it cannot be made conceptually coherent. Either our wills are determined by prior causes and we are not responsible for them, or they are the product of chance and we are not responsible for them.