Re: M. alors

From: Marchal <>
Date: Fri Apr 13 08:43:36 2001

Jacques Mallah wrote:

> I'm not sure what you mean by much of the above. e.g. 3rd person,
>numbers' relations, "accept", intensional interpretations, 1st person.
> I am a platonist, like I said. The specifics of my position will be
>clarified below.

Just take 3rd person as "objective" like in Everett thesis, and 1st
person as Everett "subjective".
Recall that I am a Platonist too.

>>BM: Implementation must be some sort of relative computations.

>I don't know what you mean by the above, or why you said it. Also, it
>does not seem to be a response to my above point.

But what do *you* mean by implementation ?

>> > It's hard to define "existence", isn't it?
>>No. Positive integers exists. Nothing else.
> I must point out that you in no way addressed the question of defining
>"existence". I am sure you do not mean to say that it is defined as
>positive integers! To be pedantic, it is obvious that "the square of 2" is
>defined to be "2 x 2" and is not just defined to be "4", even though we
>agree (after laborious calculation!) that the number 4 has the property in

OK. What I was trying to say is that I take arithmetical truth as
independent of myself, although I am "in there" with all the rest.
This follows from comp and UDA. I do not pretend it is obvious.

>>I have no problem if you want more, but in general I don't need it.
>>The "right" frontier is somehow arbitrary.
> Arbritrary ain't good.

Not at all. It fuzzifies things and make real decision easier, but
wrong sometimes, sure.

>>Consistency is an attribute of theories or machines or talking ducks,
>>not of mathematical object like numbers.

> We seem to disagree on what a mathematical object is. For me, anything
>that can be described mathematically counts as a mathematical structure.

This is circular. But then you are no trying to really define what is
a mathematical object, I suppose.

> of course, an inconsistent description does not describe any math structure.
>It is not always obvious whether a given description is consistent or not,
>and one way discussion of such a question is often framed is in terms of
>whether the hypothetical structure that would be described 'exists'. (e.g.
>"Does a power series expansion for f(x) exist?")

OK. What's the point?

> However, there are perhaps three kinds of 'existence' to distinguish.
>If a mathematical structure could (in principle) be described, then it
>exists in the weakest sense.
> A classical Platonist would say that the structure belongs in Plato's
>heaven of math; it's a feature of the world which is logically necessary.
>This is an intermediate form of existance. (Such an object need not have
>any finite description, BTW.)
> Let's define a quantum Platonist as one who goes a step further and says
>Plato's realm of math is no heaven, but includes our Earth.

I don't take a word like Earth as granted in a metaphysical argument.
But I agree that the ten thousand earth and their variants exists in

> This implies
>the AUH.

Except that U is undefined. All Universes are indeed in Plato's heaven,
none are material. They appears material to their inhabitant, that's all.

>Unlike the classical position, this requires a unique and
>inevitable *measure distribution* on the set of mathematical structures.

No. measure are relevant for inhabitant relatively to their computational
histories. And that need "trans-univers" reasoning. (A good thing, because
without that there would be no hope for a computationalist explanation of
quantum interferences).

> My position is that either the classical or the quantum Platonist
>position is true, with the latter being more likely (as it explains why
>we're here, but in its disfavor it demands a measure distribution).

It seems to me that the quantum is first person plural subjective and
is a consequence of comp platonisme. I make it "clear" formally in the
second part of my thesis.

>You cannot just say physical = mathematical.
>I agree of course, but it is not obvious. It is part of our
>work to make that clear. In particular, in
>that case, we must be able to prove F = ma, or SE.
> > We use "physical" to refer to the structure that we guess exists in the
>strong sense. If you believe in the AUH, then the distinction disappears.
>Most people don't.

I believe in the All Computations thesis, except that it is not an
independant thesis. It follows from the (arithmetical) platonism.

>>The distinction disappears ontologically only, but the appearance
>>of the distinction does not disappear and must be explained.
> We would certainly like to be able to do that. Unfortunately, as I have
>argued in other posts, the AUH is not falsifiable, so even if we prove that
>F=ma is very unlikely for us to see with the AUH, we are still stuck with
>the AUH. But it would be very unsatisfactory, of course. We need to derive
>F=ma not to prove the AUH, but to make ourselves happy with it.

The "All Computation + comp" *is* quasi-falsifiable. Mmmh...

> For me the key word is "appearances". I am sure Everett did NOT believe
>in any discontinuous or probabilistic elements in his interpetation.

First I agree with Bryce Dewitt that Everett did not propose an
of QM. Everett proposes only a new formulation which is essentially
Then he explicitely derives the Wave reduction as a subjective process,
an analysis of the memories of normal (Gaussian) classical machines,
in a universal quantum computation. (I show the last is redundant).

>Rather, he believed that, for a _typical_ observer-moment, that thought
>would include _seemingly random_ information which gave the _illusion_ or
>randomness, just like a typical member of the ordered set 000 001 010 011
>100 101 110 111 "looks like" a random #.

Yes, sure. But he cares for those illusions, and he does not call them
illusions at all, just subjective appearances.

> My interpretation of Everett is proved by his statement that "The
>behavior of these observers shall always be treated within the framework of
>wave mechanics."

Exactly. Behavior is typically objective/third person. I agree with this
reading of Everett.

>This indicates that he did NOT intend to introduce any
>"mind-like hidden variables"


> - and thus, no "1st person" merde about
>consciousness "flowing" from one observer-moment to another.

The flowing of consciousness is part of the appearances.
I still don't figure out why you want dismiss those appearances so much.
Especially talking on Everett who cares so much about it.

>>In my thought experience (UDA and the like) I use *exactly* the
>>Everett notion of subjective/objective. I call them first person and
>>third person as in classical philosophy of mind.
> You just don't understand Everett, it appears. As far as I can tell,
>his beliefs were normal (as opposed to crackpot/1st person/mind-like hidden

Everett derives the first person plural probability from the third
person SE. Why do you mix hidden variable into that. You *know* I
think that hidden variable *are* crackpot.

> Of course, his model of the observer is seriously flawed (it
>is not a computationalist model and does not address the reasons for
>considering a given set of states to be a 'memory'),

Except that he has foreseen the "decoherence of history" approach. But yes
he forgets to justify SE, that is, once you accept comp you must take
all computationnalist state (not just the quantum one) into account and
show that SE emerges also from the first person plural point of view. And
also, he doesn't take Church thesis into account, and Godel, etc.
So I did it :-)

>there is an objective measure distribution, therefore no QTI or
>other '1st person' nonsense.

I agree there is an objective measure distribution on the possible
relative consistent extension of my computational histories.
But apparently it entails COMPImmortality, and indeed QTImmortality,
I'm afraid.
And this with respect to a quite large set of possible ways for
defining "personal identity".

>> >If you say, prior to the duplication "I will either end up
>> >in Washington xor in Moscow", that's an objectively false statement.
>>Correct. I hope you will agree that if you say , prior to the
>>duplication, "I will feel myself ending up
>>in Washington xor in Moscow", that's an objectively true statement.
>>(objectively with comp).
> No. (Or at least, incomplete.) It all really depends on the definition
>of "me". At this point I can think of three reasonable ways to define it,
>but none of them would lead to that statement. The simplest definition is
>to define 'me' as a thought; then I exist only for a moment and never leave
>my home city.

Ridiculous, I am not talking to a thought.

> The closest to what you want would be to define 'me' as a particular
>implementation of a computation. I believe that in this case, some of 'us'
>would die, some of us would end up in Moscow, while the rest of 'us' would
>end up in Washington.

With comp you cannot be a particular implementation of a computation.
You can perhaps say that you are an infinity of similar computation all
speculating apparently about the existence of some magical singularising
"implementation". With comp, below our level of substitution, we live
(or "we" supervene) on all possible implementations.
That is why we "discover" parallel histories when we look "outside" or
"inside" close enough.

> But because the total measure increases in the copying process, bear in
>mind that a # of implementations must also be created.
> I say that the original implementations would die or split up, but be
>joined by their newly created brothers in the new cities. (Mathematically,
>recall that I am referring to sets of mappings which satisfy the transition
>rules in question. A mapping could refer both to my original body and to
>the particles used to create a new body; such a mapping could survive the
>transition. I should study this more carefully, e.g. to find out if the
>fraction that do this is large or negligable.)


> Finally, I could define 'me' as the set of all such implementations.
>Then I should say "I will feel myself ending up in Washington and not in
>Moscow, _as well as_ in Moscow and not in Washington." (In different
>observer-moments, of course.)

And this makes sense for the "panscient spectator", in a third person
sense. Nothing really related to you.

> [snip]
>What does differentiate different

Memories. Cosmological, genetical, individual memories. I would
say. Most of the time there are organized into histories, so I could
have said simply: Histories. Isn't it?

> - - - - - - -
> Jacques Mallah (
> Physicist / Many Worlder / Devil's Advocate
>"I know what no one else knows" - 'Runaway Train', Soul Asylum
> My URL:
>Get your FREE download of MSN Explorer at

Received on Fri Apr 13 2001 - 08:43:36 PDT

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