* If the brain is the source, or foundation, for consciousness then there cannot actually be an observing self. Though it's a pervasive and convincing phenomena it can't be real, or we'd be back in dualism. If we tell a materialist that they're going to be painlessly and instantaneously killed, and replaced with an identical copy, in theory they should be OK with it. It seems like something is going to be lost - them - but materialist logic dictates that this cannot be so in reality
This premise is wrong. Even to materialist, copy are all different instances. You are asking if be8ing replaced by another instance and getting killed is fine.
Hu. No. There is absolutely nothing in materialism which state that. You make the same type error of judgement that religious people take toward atheist "yeah then if there is no paradise and hell then there is no need for moral and everything is allowed". Hu. No.
The brain is the SOLE basis of consciousness and from its physico chemic property and networking emerge various physico chemical process in network. The sum of those processes is what gives us our feeling of self, and you can as accident, illness , stroke, destroy part of them changing the self. Those sum is what is called the observing self. There is no indication either that that emerging process needs duality of any kind.
Finally, again, I have to wonder why it is so hard for non materialist to swallow, identical copy are not the same instance ! Killing an instance spells its end ! Why would such instance accept being replaced by a copy ? There is nothing in materialism which state that various identical instance must accept to be replaced by each other. In fact materialism state that all those copy instance are
separate entities with
separate emerging consciousness. Think of it as
perfect twin with the same memory than copy. Why would a twin accept to be killed and replaced by his brother ?
That make no sense. Do not attribute to materialist what they do not say.