[Illuminated One]

Originally Posted by Squirrelloid

The other alternative is a world where there are no physical 'goods'. Of course, since survival requires physical 'goods', this means everyone is dead. Of course, once everyone is dead, no agent need conflict over values.

Ok, i think i've identified the perfect world. Its this whole life thing that causes the problems.

A good point.
Of course you are meaning that we wouldn't exist in such a world, but it is not a question of life it's a question of consciuosness.
What you do have to prove is that conscious existence is impossible without life and physical goods.
Still there are other possibilities, say Solipsism. The world is exactly like what it is (or more exactly what I believe it is) only that everyone except me is a biological robot without sentience that are programmed to act exactly like they do. I couldn't tell the difference and I couldn't hurt anyone. I'm not saying this is going towards the perfect world but towards a world in which it is impossible for agents to hurt each other - and as I said there would be sacrifices.

It would strike me that you'd just allow people to make arbitrary claims without any consequences, which leads to the worst sorts of discussions because nothing can be concluded.

Nah, the worst kinds of discussion are those in which positions are forbidden arbitrarily in order to get to a conclusion.
Of course you can point out consequences like "whatever 'laws' it obeys will have unforeseen corellaries that won't be able to be enumerated, and will be so alien from our experience" but then it is your tasks to prove that before it is a meaningful argument and not an arbitrary claim in itself. Another set of laws will have unforeseen consequences? For sure.
Every possible set of laws will have unforeseen consequences which are exactly the way you need them for your argument? Wait, you have gone through them all? Or have you foreseen it?

Heck, physics taught me i can put words to lots of things I can't actually envision, and those are *real*.

And hence your argument about the inconceivability of physical impossibilities falters. Since physical reality itself is inconceivable by the standards you have to demand.