On 04 Mar 2011, at 15:13, 1Z wrote:

On Mar 4, 7:57 am, Bruno Marchal <marc...@ulb.ac.be> wrote:
On 03 Mar 2011, at 18:39, 1Z wrote:

If you have a UDA inside a physical universe,

I guess you mean "a UD inside a physical universe".

UDA is for the UD-Argument. The Universal Dovetailer Argument.

there is real physics
(qua physicalevents)
outside it, and there is a real study of physics outside it as well.
What goes on in a
virtualised environment is not real. You could feed virtualised people
false information
about the past, but that would not be rewriting history (in the sense
of changing the real
past) and it would have not mean that the virtualissed people had some
valid kind of history qua study of the past) either, since it would
not be based
on true facts.

That might be consistent in some theory.

ie the common-sense intutions most people have

We can use common-sense to find on what we agree, not for disagreing about a conclusion of a reasoning. "Everyone knows that" is not available as argument in science. Cf: "Everyone knows that the sun moved around the earth".

But you elude the reasoning
and the questions.

Likewise, their "phsyics" would not really be phsyics
, because it would not be based on the only real phsyical reality, the
one in which
the UDA is embedded.

Sorry but in this case, it would be based on the 'real physical

It would not be based on empirical data about the real physical
reality. It would be based on it ontologically, but they would
be unawae of that

That's the point. How could you then be aware you are in the first physical universe, and not in the virtual but still physical universe without finding a flaw in UDA[1-6]?

The UD is physically running in that universe, and by the
first person indeterminacy, even if you do an experiment in the
physical universe, your first person experience remains determined by
the physical computations made by the physical UD. So to connect your
experience with the physical reality, that physical reality has to be
retrievable from the mathematics of the UD (computer science/number

But there is no guarantee that  a virtualised person would
have any epistemic connection to physical reality.

So you reject the step 6?

of them might see a realistic simulation through coincidence,
but it is doubtful  that coincidence can found knowledge.

There can no be coincidence, given that what will happen from the first person view is a sum on an infinity of computation. (A friend of mine has perhaps find, today!, a way to justify the role of the complex numbers from just that).

There is no particular reason to think that
phsyics (qua study) that is baeed
on false information counts as physics in the true sense of the term.

You always manage to use the term "true". But we cannot use that term
when doing science. We put our assumptions on the table, and we reason
from there. You are wrongly "using" the term "truth", like pseudo-
religion wrongly use the term "God", like a sort of authoritative thing.

The kind of truth in question here is stipulative definition. To
say that physics is the study of flowers or rocks is not to use
the true, correct, conventional meaning of "physics"

When working on the mind-body problem you cannot take anything granted, neither on mind, nor on matter (and thus physics) without taking the risk of begging the question. Anyway, I use physics in a sense accepted by most physicists: the science of what is observable and predictive locally.

If "physics" *means*
the study of what is ontologically fundamental, then what is going on
in the UDA can
only be pseudo physics.

Then you have to say "no" to the doctor, because he will build a
pseudo brain.

I have to say no to *a* doctor who will not build a physical brain.
I can still say yes to a doctor who promises to reincarnate me
in silicon.

OK, but then the reversal occur in any universe running a UD made with silicon.

The point is that once you have said "yes" to the
doctor, qua computatio, you can understand that your next most
probable first person state will be more related to the infinitely
many third person corresponding states run by the UD than by the one
single out as being the "true universe", even if that concept makes

But I don't have to accept that physics becomes reversed. I can
take the view that there is no study of physics, properly
so called, in the UD.

Then there is no physics at all anywhere, or you have to find a flow in UDA[1-6].

On the other hand, if "phsyics" just means
"investigation of subjective phenomenology""
then the argument goes through -- but only because that particular
definition of physics is
doing the heavy lifting. It isn't difficult to prove that physics
isn't about objective reality if
you  have started with the assumption that it *is* about subjective

I do assume there is a physical reality. I would not talk on doctor
and digital brain if that was not the case.

Then your conclusion that there isn't physical reality is in

I think you confuse the idea that physical reality exist (which I accept, given that I try to explain it) with the idea that physical reality is the fundamental ontological basic (primary reality) reality.

All what I say is that comp makes physical reality necessarily explainable by (infinities of) arithmetical relations. I have never said that there isn't any physical reality. The step zero of UDA, i.e. the definition of comp, would already be total nonsense.

The only assumption is
that a digital brain, physical and constructed from piece of matter in
my neighborhood, is able to sustain my consciousness together with my
current correct relative computation. I would not say yes to the
doctor if this could change the frequence of observable, by me, white
rabbits, for example.
This means that the UD, generates the right measure of computations
corresponding to my observations. Below my level of substitution, it
generates all the possible continuation, and so that fuzziness should
be observable, and should be the bottom level defining what I will
take at first sight to be primary matter. Comp reduces the physical
laws to a measure on provable (sigma_1) arithmetical propositions
weighted by the proofs/computation (the arithmetical UD).

I don't have to accept that what the acitvity performed
by scientists in the UD is actually physics. I think it is

This is incoherent with steps [1-6]. Which one?

 If you still don't see this, ask for clarification of the sane04
paper(*), because it seems to me that the first seven steps are rather
clear, there. You have mentioned the WR. I take from this that you do
understand the six first steps, don't you? The seven step follows
mainly from the invariance of first person experience for change in
the delays of the (virtual) 'reconstitutions'.

The eighth step is really more conceptually subtle, and the clearer
presentation I have done until now is in this list in the "MGA" thread
(the Movie Graph Argument). It shows that the "real concrete UD" is
not needed for the reversal to occur.

Also, each time you use the term truth and real, you have to recall
what is your assumption, and to relate your notion of truth to it. No
one can be certain of the ultimate third person (public) truth.

I don't need ultimate truth, I just need words to mean what
they usually mean.

This is not available in science. In complex issues we have to be flexible on the meaning of the words, and inflexible on the validity of the reasoning.

What I know, because you told us, is that you assume (well, that was
probably not your wording) the existence of a physical universe, being
primitively physical, and made of some primary stuff, which would be
ontologically existing and not made of, or reducible to, simpler
What I try to explain, is that if you are using this primary matter to
singularize and make existing consciousness, then the primary matter
AND the mind associated with it have to be non Turing emulable.

Matter doesn't have to be non-turing emulable *maths*.

This comes at step 8. The reversal appears already in step 7 for *robust* universe.

Mind can still be Turing emulable, since your conclusions can
resisted by rejecting Platonsim and keeping comp.

Show me where in the reasoning the term "Platonism" is used in your sense. The current question I did ask you explicitly here is "do you get the point that in a Robust universe the reversal does occur (independently of "Platonism")?". Then we can go to step 8 to see that a form of Platonism is a *consequence* of comp.


assumes the mind to be Turing emulable, so you better say "no" to the
... unless you realize, may be, that, after all the physical laws
might be not primitive, but themselves selected by the 'consciousness-
filtering' on infinities of arithmetical relations.

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