On 21 Jun 2016, at 18:29, John Clark wrote:

On Mon, Jun 20, 2016 at 9:44 PM, Jason Resch <jasonre...@gmail.com> wrote:

​> ​Bruno has shown that arithmetic is a viable candidate for explaining physics:

​Bruno wasn't​ ​the first to discover that,​ ​people have​ ​known for​ ​400 years​ ​that mathematics is the best language for describing physics, but the point is mathematics is a language​ ​and​ ​physics isn't, physics just is.


I give an example, with arithmetic.

You have a language, that is, symbols and grammar. The symbols are the parenthesis, "=", the logical symbols (&, V, ->, <->, ~, E, A), and the non logical symbols, proper to arithmetic: 0, s, +, *. Then the grammar tells you which expression using only those symbols is grammatically correct or not, for example s(0) + 0 = s(s(0)) is a grammatically correct formula.

Then you have the semantics, given by the usual structure (N, 0, +, *), with the usual abuse of language, denoting the same way some well known function from N to N, or NXN to N, with the symbols of the arithmetical language. With such a model, we have a notion of truth. For example "(Ax((x = 0) V (~(x = 0))) is true if for each natural number (object of N) we have that either that number or not.

Then you have the theories, which are like lanterns to look at what is true in all or some model(s) satisfying some formula.

I gave two very different theories for arithmetic.

One is Robinson Arithmetic (RA, Q):

 It is Classical  Logic +

0 ≠ s(x)
s(x) = s(y) -> x = y
x = 0 v Ey(x = s(y))
x+0 = x
x+s(y) = s(x+y)
x*0=0
x*s(y)=(x*y)+x

That is a very weak theory. It cannot prove that 0 + x = x, for example, nor that (x + y) = (y + x), and is very poor in generalisation. Yet, it can already prove for all digital machine x that it stops, in all case x stops. It can represents in some strong sense all partial computable function; it is sigma_1 complete, that is Turing universal.

The other is PA. It is RA + the infinitely many following axioms, where F is for any arithmetical formula written in the language described above:

(F(0) & Ax(F(x) -> F(s(x))) -> AxF(x)

That gives PA a strong generalization ability, and it makes PA Löbian (its propositional logic of provability obey G and G*, which main axiom is Löb's formula []([]p -> p) -> []p. Exercise: derive Gödel's second incompleteness from L. Hint: replace p by the constant proposition false (f).


And even if it turns out that I'm wrong and that in some sense mathematics is more fundamental​ ​than physics it wouldn't change the status of what this list is unhealthily​​ (in my ​humble ​ opinion) obsessed with, consciousness.


Thanks for precising it is your humble opinion. But consciousness is what you hope to be preserved when they will give you a digital brain. And we are not obsessed. We might be tired of its being pushed under the rug.



Whatever consciousness is one thing is very clear, it can't be produced entirely from the ​stuff at the ​fundamental level of reality,

Ah! Glad you saw this.



and being more fundamental is not the same as being more important. Atoms are more fundamental than molecules but molecules have properties than atoms don't have, and molecules are more fundamental than life but life has properties that molecules don't have; in the same way consciousness needs intelligent behavior and intelligent behavior needs computation and computation need​s​ physics.​


No. The notion of computation belongs to arithmetic. Only a physical implementation of a computation needs physical assumptions.

The physical remains possibly (and necessarily with digital mechanism) an aspect of Arithmetic when seen from inside, and taking the First Person Indeterminacy into account. We just take into account that no universal machine can know by introspection which computations realize her among all computations which exist, in the sense of the theory above. Digital mechanism predicts that when we look at ourselves below our substitution level, we must witness the many-"realities/computations", and that explains the startling aspect of quantum physics. That does not mean computationalism will not been refuted tomorrow, but until now, it is the only theory, it seems to me, which explains both mind and matter in a coherent way, without discarding the complexity of the 1p and 3p linked complex relation.

I don't think it is so much harder to swallow than QM without collapse.

Bruno




 John K Clark​







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