That's a bad example, since I find the ritual of communion to be tedious, pointless, and a little creepy. Clearly the value of this concept is subjective, and its utility unclear. You need to come up with an example of a concept that makes no predictions but is demonstrably useful if you're going to argue that the utility of a proposition lies somewhere other than its ability to form a predictive model.
You have explicitly defined utility as what has predictive value. As long as that is how you define it, I cannot show utility outside a framework so construed.
What I have said, is that something will not survive, nor be propogated, if it does not have use of some form. Something or someone is getting something out of it. To me, that is utility of the concept. We are therefore at a semantic impasse, I am afraid.
I'm not defining subjectivity as objective, I'm naming the only objective facts I, as a subjective, non-omniscient being, am capable of apprehending, and those facts happen to be about my own subjective experience. Whatever my subjective experience is, even if it's inconsistent from moment to moment, is objectively what I am experiencing. How on earth does that invalidate intersubjectivity? At worst it lacks a way to confirm intersubjectivity, but please explain how it dismisses that concept a priori.
As for schizophrenics, guess what? They can't "philosophy" their way out of their disorder any better than we can "philosophy" our way out of solipsism. They are stuck in their delusional reality just as we are stuck in ours. Seriously, if you have a solution to hard solipsism that isn't just an axiomatic assumption, please write the Nobel Prize Committee. If actions based on delusions turn up results that match expectations, how is that delusion not useful? That's no different than a mythology that has demons in everything that can harm you and angels in everything that helps you.
I don't presuppose anything about a mind-external reality, in fact my axioms are all pertaining to my personal, internal reality. I do think I can make strong arguments for its existence, but I don't think that's necessary as no one seriously disputes this. Again, you can take any beliefs you want as axiomatic, but if it pertains at all to a presupposed external reality, ie what it's made of or what exists in it, you're putting the cart before the horse. I can presuppose that I personally am the Ground of Being, axiomatically, and we'd be on equal philosophical footing. Clearly, something's wrong here.
You say your only objective facts are your subjective experience and then deny you are calling subjectivity the Objective? Ok, then.
Yes, as I said, you either have to be solipsistic, incoherent or presuming metaphysics. Clearly you have opted for solipsism. That's fine. It does mean though, that as you can only perceive intersubjectivity via your own subjectivity, that it is merely an aspect of the latter. Thus your experience is your own, and my experience merely your perception of my experience, and so forth: not real intersubjective relations. For anything that might be a real meeting of minds, of different individuals, a framework from within which they both operate, has to be construed, so that my admittedly subjective data, becomes but a shade of an objective relation which it can tend toward, more or less closely. Intersubjectivity means we perceive another's subjective experience, after all. As you said, you cannot confirm Intersubjectivity, but if our data cannot be anything other than solipsistic personal experience, then in actual fact no perception of another's subjective experience takes place. We have merely our own shadows cast, our own simulation of what we think another is experiencing, and denying that this might in some way be a real reflection, therefore, as 'real' reflections are only our subjective experience itself. It is a bit of a snake biting its own tail, which was why I tried to make a thread specifically to discuss this before (I placed a link earlier), as such may be mired in much involved conversation. To presuppose that your own personal reality is so absolute, has quite a whiff of hubris to me, though.
One wonders, then, how anyone who hasn't died is even aware of this difference that is only apparent to the individual after one's death.
It is apparent now. You just need to be experiencing it. People are just playing the game by different sets of rules, and may only realise this when it is done. As I said, martyrdom makes sense if God is real, but otherwise not, and thus real world application of the metaphysics abound. I used to be an Atheist, before converting. I experienced both sides of the coin, as it were. The difference is stark. As you said, we can only intrinsically know what we are ourselves experiencing, in some sense. You asked what real effects are different by the truth of God, and everything is in fact, different. It might not appear so to someone who does not perceive it though, as a colour-blind person might see two different colours as the same one.
To quote Lewis: "I believe in Christianity as I believe the Sun has risen; not only because I see it, but by it I see everything else."
Everyone's reality is a solipsistic one, whether they admit it or not. Your determinations are only irrelevant to me if they fail to demonstrate any predictive utility. If your epistemology doesn't work in this way, I have no idea how you determine what's relevant and I don't care.
Exactly. You have defined what is useful to you, how you see utility, what is relevant, and all else you dismiss. Everything is determined by the framework from within which you are working.
This was my point on why Science for instance, is not busy with the same things as religion. The latter has a broader perspective that may encompass the former, but if you limit yourself to Science's view of Methodological Naturalism, the rest seems an incomprehensible Other. This does entail an Ontological Naturalistic assumption then.
Without stepping outside the narrow grooves we have rutted our thought into, this becomes harder and harder to realise, and our own determinations are given undeserved paramouncy. A human error, and the reason why CS Lewis suggested you always read two old books for every new one, so that you don't become mired in our own present idiocies, but can have the fresh wind of history expose its strengths and flaws. It is hard to spot error while you are busy making it.
This is a false analogy. Your a priori assumption of the existence of God constitutes an assertion about a mind-external reality which this God must occupy, also called a synthetic proposition. I've already explained why that's problematic. Russel's attempted proof is not an assumption, but a logical proof based on mathematical axioms, which are just a set of rules governing the formal use of language. Taking mathematical axioms to their logical conclusion is not the same as taking a synthetic proposition as axiomatic. It's the exact opposite.
@Silmarien has already nicely adressed this.
I don't believe in a fishbowl universe, with God looking down from another 'space' as it were. I think this hopelessly anthropomorphic and is really not how classically a lot of ideas were framed. Plato's world of the Forms was not, for instance, a 'separate space' in that sense.
Anyway, it was not meant to be an exact analogy, but to give the idea I was talking about. If I base ideas off one concept, it doesn't mean that I am assuming that concept as well as others derived from it, if someone else accepts the latter, but not the former. A set of derivations is not itself an assumption in toto as well, if someone does not accept the original proposition. If I deny the central tenets of Buddhism, it doesn't mean that I think all derived Buddhist theology are thus each individual assumptions. This is utterly silly. A syllogism based on a false premise might be invalid, but its individual consequent terms do not therefore each become premises on their own within it.
