Hold on, now we have to be careful.
Let's suppose for a moment that the physical reality is all that is.
We can suppose that. That would be a supposition that physicalism is true. The trouble is that so far, Paul hasn't been able to define "physical", so we aren't sure what "physicalism" even means.
But we certainly have to be careful.
Let's consider the small four-legged chair that I right now see in front of me. Let's call the chair A1 and my observation of it O(A1). These two things are patently different. True. It would be extremely non-physicalist to claim that they were the same.
So what we have called "P1", you have called O(A
1, and what we have called "P2", you have called A
1. That is fair enough. You are implying that the "real chair" is P2 - the cause of the experience rather than the experience. And you have accepted that these things aren't the same. All sounds good so far.
But if there is nothing that is not physical, then that observation O(A1) is another physical thing, let's call that A2.
A reminder of my note in red at the top of the proof:
NOTE: If you want to challenge this proof then you must challenge either the premises, the definitions or the reasoning. What you must not do is make some other sort of statement, which depends on an assumption that physicalism is true (thus assuming the proof fails before examining it), and claim that this means the proof is false. Any responses to this proof which take this form will be rejected on the grounds they they have nothing to do with the proof.
Asserting that physicalism is true and then claiming that this is sufficient to refute a proof against physicalism which makes no assumptions about whether physicalism is true simply
doesn't work. Here is your line of reasoning:
1) Assume physicalism is true
2) Therefore, even though we've already agreed that P1 and P2 aren't the same, they both
must be physical.
This is a proof against physicalism by contradition. You are correct. If physicalism is true then P1 and P2 must be the same (or one of them simply doesn't exist). But P1 and P2 aren't the same, therefore physicalism is false.
You can't defend physicalism by assuming it is true anymore than you can do the same thing with the Bible:
1) Assume the bible is true
2) Therefore, even though we've already agreed that we are evolved from worms, this cannot possibliy correct.
3) conclusion : We didn't evolve from worms
Doesn't work, does it?
