What do you believe in that hasnt been proven to exist?

[Excited Penguin]

Do you agree that consciousness is a physical process arising in the brain ?

Yes, of course.

If so, why do you think it possible that the world's existence may be predicated on your experience of it ?

I think you've misunderstood me.  I do NOT think it is possible that the world's existence is predicated on my experience of it. 

All you have described is this hypothetical connection between awareness and reality that you think may or may not be there, but you haven't explained it. 

OK, now I'm SURE you've misunderstood me.  I don't in any wise 'think it may or may not be there'.  I am of the belief that reality exists whether I'm aware it or not.  What I cannot do is prove that this is the case (which is the whole point of this thread).

My own position on the matter is that this is either an unknowable or meaningless proposition to begin with. 

I'm not sure it is useful to describe questions of reality, existence, or consciousness as 'meaningless', so it's fortunate for me that I wasn't proposing anything at all.  I do, however, agree that whether external reality exists is unknowable.  More to the point, it is also unprovable, which - again - is germane to the thread.

Boru

I think trying to assign such properties as knowable and provable to existence itself is an exercise in futility. Experience of the world is there. The world itself is there, in some sense, no matter what may turn out to be the case. Therefore, I still think this questioning of or indeed belief in reality is simply meaningless and useless at best.