This is weird. First you tell me that the thing I'm describing--the "physical world"--is the One. Then you say that the One is not physical. But I didn't say it was. In one fell swoop you're telling me what word I should be using, and then telling me that that word is wrong. I'm sure this is unintentional, but re-read the above and you'll see what I mean.
What you understand or possibly could understand about the physical world is the realm of the One. The physical world is a world composed of objects. One-ness is equivalent to object-hood.
When we speak about existence, we speak about the physical world. When we speak about being, we speak about both the physical world and that which is not the physical world.
Lemme draw a couple pictures.
Which leads me to a question that probably sounds more adversarial than I mean for it to sound: why do we need these terms? I understand that sometimes we need new terms in philosophical discussions to define new ideas. But the purposes of this are always clarity, and I don't think these terms are adding to clarity. Moreover, I think they might be superfluous. Why not "Metaphysical" and "Physical" instead of "One" and "Multiple"?
"Metaphysical" means what exactly? What does it mean to you? It means different things to different philosophers. For example, if you mean metaphysics what Heidegger meant by metaphysics, then you are still talking about objects, so you are still in the realm of the One. Honestly, I don't really care what it means, because there's no need for it. It could be called "Bob" for all I care.
The reason why "One" is used to stand for the World of physical objects is because it relates existence to the number one. Again, I could call it "Hubert" if I wanted. It brings mathematics into fold as a discourse on being. Your guy Nash totally understands the centrality of the concept of One in talking about being, but what exactly he means by it is a different story.
Anyways, One-ness is as simple a concept as you can get. For me, it's the primordial concept of existence. To exist is to have One-ness. To be is to be Multiple. If you exist, you can be counted. Like counting... one, two, three. It's a very intuitive name for what the realm of existence is.
I think you really need to define "supernatural," then.
I can't define it in any terms or ideas I subscribe to, because it makes no sense. It's impossible. There is only the Multiple and the illusion of the One. There are no other configurations of being or existence. 'Outside' is an inherently contradictory idea. Even giving you a definition of it would force me to use senseless notions like 'outside' or 'transcendent.' Only immanence is possible for the materialist. That's why it's a truly atheist view. It's not agnostic about God like, say, science is. It totally prevents any concievable notion of God.
If I'm understanding you correctly, things like abstract concepts are not physical, but neither are they supernatural. If that's what you're saying, I'd say: to a materialist, yeah, they are physical. Not in a way we can easily detect, but ultimately they are the byproduct of physical interactions.
Can you count concepts? Like, can you count the number of concepts that you use? Yeah. So they are One. Can you count the number of abstract concepts you know? Can you say "this thing here is an abstract concept that I am articulating to you right now?" Then it is One. It's that simple.
The Multiple is that which breaks down the One so that it no longer exists. The materialist claim is that any One can be broken down into Multiple, so that, in the end, only the Multiple is. Amazingly, you seem to be open to the idea that everything can be broken down into the Multiple (definitely an attribute of someone who's rigorously considered a lot of things philosophically!), so it simply follows from this property of existence (it's destructibility) that only the Multiple is.
NEVERTHELESS, as you know, we can concieve of a lot of things as One. This is not just because they are 'useful,' unless you mean useful in a very strong sense in that we could not really have any thoughts or activity at all in a world that recognizes the Multiple. In some sense, the fact that the Multiple is 'unusable' makes the emergence of the One a given. The One is simply that orientation within the Multiple that makes the Multiple 'usable.'
All you need to explain then is the One-effect, and the materialist explanation is that you can find the One-effect as a property of any so-called object.
Plato's explanation for the One-effect is the transcedent Ideas. Aristotle's explanation for the One-effect is the hylomorphic model of form and matter.
These are all valiant attempts, but they aren't really necessary. All you need is the Multiple. The Multiple sustains its own illusions. This is the materialist stance.
At this point, you need to stop saying 'to the materialist.' You can just say 'what I think a materialist is,' and the moment those two match up, then you get my view.
Right. They don't believe in anything outside of the physical. So, what are you trying to accomplish? Are you trying to say they should? Are you trying to show how they can not believe in anything outside of the physical, but still have free will (if so, how?)? I'm not at all clear on what you're arguing for, except that you seem to always be arguing that people are not using these terms correctly. But to what end, I can't tell.
... no
The physical is the realm of the One. The Multiple is ALWAYS outside the realm of the One. The One, the physical, is not exhaustive of being.
Free will is simply that will (will is an object, a One) which acts from its own Multiple supplement. The reason why I insist on maintaining the legitimacy of the ideas of Truth, Beauty, the Good, Freedom, etc. is precisley because you think these can only be justified by God.
To be totally vulgar I can just say THE MULTIPLE IS GOD, but this is totally misleading, because it's nothing like God. It merely encompasses the OUTSIDE where you think God is.
The feeling that there is 'something more' to physical existence is TOTALLY JUSTIFIED. There's just no need to go to God. The Multiple is already there. There's no room for God.