-----Original Message-----
From: Bruno Marchal <[EMAIL PROTECTED]>
Cc: everything-list@eskimo.com
Sent: Thu, 1 Sep 2005 12:30:20 +0200
Subject: Re: subjective reality

On 31 Aug 2005, at 16:20, [EMAIL PROTECTED] wrote:

> I think most people would grant you that the mind-body problem has > not been solved.

Not meet them so much in my experience. Positive Religious (like Muslim, Catholic, ...) have build-in solution. It is most of the time tabu to question them. Negative Religious (like Atheist) have build-in solution, but are generally not aware of the religiosity of their solutions. Only (serious) philosopher of mind/cognitive scientists are aware of the problem.

I would leave the "soul" out of my statements. The soul-body problem was solved long time ago.

> They would probably would also agree
> that 3 classes of solutions (at least) have been presented over > the centuries, namely, (1) Physicalist solutions (there is no mind > stuff!) (2) Pure Idealist solutions (there is no body-> stuff=matter) and (3) Dualist varieties where both exist and you > try to figure > out how the two stuffs interact etc... It seems to me that your > attempted solution is of type (2), Am I right?

Well OK. I guess you make the difference between solipsism and idealism which can be realist or platonist. The mind stuff is just numbers and their dreams ...

What do numbers dream about? And do the name sheep to go to sleep?

> You do however
> invoke a favorite classical physicalist hypothesis in the form of > YD and than you "turn the tables" on it, so to speak, no?

YD has nothing with classical physicalism, unless you assume physicalism at the start. YD does not assume a universe physically exist, only that "I" exists and that I am supported by a relatively stable (sheaf) of computations. Actually the use of the YD in the UD reasoning is accompanied by an explicit postulation of a physical universe for making the reasoning easier, but that hypothesis is explicitly eliminated toward the end of the reasoning.

It seems to me that most of your statements mention assumptions that you accept as starting points only to show that they are not needed in the end! If you assume that the I is "only supported by a stable sheaf of computations" aren't
you already assuming what you mean to prove?

> I think that the YD motivation is the weakest link in your chain > (a real Trojan horse because it is physically untenable)

I really don't understand. To make YD false you must associate yourself to something non-turing emulable. Nobody has ever found a non, turing emulable process. Recall that quantum-like indeterminacy can be retrieved in the self-discourse of self-duplicating machine. Also, with some notable exception like Penrose, everybody accept YD. I teach about it since more than 30 years, and only strict dualists (with assumes explicit substancial soul) criticize it. I told you that those who get my point (of the UD Argument) and still soes not accept the conclusion prefer to abandon Arithmetical Realism. It is an empirical discovery in the sense that (I think we agree here), it is almost nonsense for me to abandon arithmetical realism.

This is patently false and even more so in your much loved platonic realm which is quite infested with non-digitally computable entities. Turing was careful to provide an example called the Halting problem and he also proved that most real numbers are incomputable but there are many others problems that have been proved Turing un-computable over the years and mathematicians keep finding such instances (tilling problems are one big source of examples). Furthermore people that work in neural network Learning Theory have began to show that there are by-example methods for leaning uncomputable problems which I think are very relevant to this question.
Read for example:


In physics it is a bit more dificult to argue the uncomputability of natural processes whose phenomenology one has not studied fully but there are surely instances of uncomputable within physical theories that we already know. A classical paper on these
issues in cosmology is by Hartle and Geroch. You will find it at:


There is also a recent book on the subject (which I have not seen) by Barry Cooper and Piergiorgio Onifreddi.
You can read a review of it at


About QM the problem is not simulating indeterminancy but simulating quantum correlations by local mecanistic means which is how Turing machines compute! Failed attempts to produce such emulations by Wolfram are what makes his book well...

About AR I think you also have a misconception of it: AR is the believe that numbers exist, not the ONLY number exist! That would be more like pythagorianism, I believe. In any case I am not suggesting you abandon it...

> to so
> if you use just to demolish it later, why use it at all?

This is the eleventh time you confuse "p -> q" with "q -> p". Unless (here) you mean by "demolish YD", the non use of YD in the translation of UDA in arithmetic.

So, you don't demolish it, you just abandon it. OK.

> Why not proceed to that interview directly?

You can. But this is like going from physics to the study of differential equation. Here it would consist to go from cognitive science to pure mathematics. Actually if you justify that probability *must* obey to the Bp -> Dp rule (probability one of p entails the probability of ~p is not one), then OK, you can extract the comp-physics from math alone. But how will you explain the Bp -> Dp rule in that context? Why suppress a motivation which also makes the link with theology: the fact that the comp-doctor cannot pretend that "science" has show that you can survive with an artificial brain (in case comp is true).

Sorry, but I don't follow here! You get physics but you loose theology!!! Why do you need the theology?

> Can that be done and leave your argument intact? That would make it
a lot more interesting in my opinion...

You are in minority here, but this is just because most people agree with YD (or at least it makes sense as an hypothesis in the cognitive science).




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