I think your redefinition of illusion is problematic: "Hey, I see an oasis on the horizion... no, wait, it's not actually there. I guess my definition of 'oasi

I think your redefinition of illusion is problematic: "Hey, I see an oasis on the horizion... no, wait, it's not actually there. I guess my definition of 'oasis' was wrong." Typically, when we use the word illusion, we tend to make a couple of basic metaphysical assumptions: 1. There's some reality external to my perception of it, 2. My perceptions can be wrong, and 3. The illusion I'm perceiving doesn't refer to anything externally. When used in the case of free will, I think we mean something more along the lines of "generated by our own minds," which is not necessarily how people have historically viewed it. Yes, "something is there" as you say, but only in our mind, like dreams, hallucinations, or mirages are only in our minds. So I think "illusion" is a perfectly reasonable word for this self-generated phenomenon.