On 7/2/2012 2:09 PM, Jason Resch wrote:

To summarize our conversation up to this point: BM: Do you really not see any difference between tables and chairs and people and numbers,JR: Chairs and people are also mathematical objects, just really complex ones with alarge information content. This is the necessary conclusion of anyone who believesphysical laws are mathematical.BM: No, it's a necessary conclusion of anyone who cannot distinguish a description fromthe thing described.JR: I think the identity of indiscernibles applies: If no distinction can ever be made(by observers within a mathematical universe and observers within a physical universe)then there is no distinction. You are using "physical" as an honorific, but it adds noinformation.BM: I can point to a chair and say "This!"JR: Yes, but how do you know you are pointing to a "physical chair", rather than a"mathematical chair"?BM: I know I'm pointing at a chair. I don't know what at 'mathematical chair' is. Canyou point out how it is different from a chair?I think we both agree that if the universe follows mathematical laws, then observers canmake no distinction between whether they exist in a platonically existing mathematicalobject, or a physical universe. If you agree with this, then there is no fundamentalontological difference between chairs, people, and numbers, that I can see.

`No. The mathematical laws of physics (e.g. the standard model) leave initial conditions`

`undetermined, they assume inherent randomness (symmetry breaking), they don't specify why`

`they are the laws of physics instead of some others. So the ontological difference is that`

`some things exist and some don't. This distinction doesn't exist in Platonia:`

`exist=having a consistent description. In physics exist=a member of the ontology of the`

`fundamental model.`

`That's why Everett, to avoid having some randomness, postulated that we exist in many`

`copies. Others have postulated multiple copies of the universe beyond the Hubble radius`

`or in separate inflating spacetimes. Tegmark proposed "all mathematical structures".`

`Most of this strikes me as a metaphysical stretch to equate the physical world with the`

`Platonic. In Platonia everything not self-contradictory exists. There is no difference`

`between logical and nomological. Our universe is 'explained' by anthropic selection from`

`everything. So do you think there were chairs before there were people? Were there`

`numbers before people?`

Facing the question: is the universe a mathematical object, or a physical one, we mustevaluate the two candidate theories as we would any other.

`That's not the question. The question is whether all mathematical objects exist while`

`only some physical ones do. In the latter case we need to find which physical ones exist`

`and what is their mathematical description.`

Does one theory explain more, does one make fewer assumptions, etc. The existence ofthe physical universe does not explain the existence of mathematical objects

I think it does. See William S. Coopers "The Evolution of Reason".

, but the converse is true.

`But only in the cheap sense of 'explain' like "God did it." Bruno at least limits his`

`fundamental ontology to digital computation, but even this threatens to 'explain' too much.`

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