Re: A calculus of personal identity

From: Bruno Marchal <marchal.domain.name.hidden>
Date: Thu, 29 Jun 2006 15:04:55 +0200

Le 28-juin-06, à 14:52, Stathis Papaioannou a écrit :

>
> Bruno,
>
> I have cut out some of your detailed response to my post where I think
> we basically agree.


Good idea. Of course it will looks like I disagree with all what you
say, but just remember we are concentrating on those points where we
disagree, or where we misunderstand each other. A case will be made
that it could be a question of vocabulary, but perhaps also I am nearer
  to Lee Corbin on those points; we will see.



> There remain some differences, and some failings on my part to
> understand more technical aspects of your work.


OK.



> Yes, sharing the memory is *not* the same as having the original
> experience, but this applies to recalling one's own past as well.


Are you really sure? When two people share memories, they can only
share third person information, which will trigger their respective
unsharable first person identities/memories.
When recollecting our own memories, we do recollect (approximations) of
our unsharable first person memories, which *does*, in the present,
participate into our present first person identity.



> You may argue that recalling our past is different because we have
> just the right brain structure, other associated memories and so on to
> put it all in context, but in principle all of these might be lacking
> due to illness or the passage of time, or might be duplicated in a
> very good simulation made for someone else to experience.


Yes. Note that from a first person memory POV, perfect quasi memories
are not distinguishable from "real memories" (if that means anythings:
assuming comp "real" memories and artificial quasi memories are just
equivalent).




> The only way to unambiguously define a first person experience is to
> make it once only; perfect recollection would be indistinguishable
> from the original experience, and it would be impossible for the
> experiencer to either know that he was recalling a memory or to know
> how close to the original the recollection was.


I agree.




> The postulate of a first person entity persisting through time
> violates the 1st person/ 3rd person distinction,


I am not sure, although it makes sense, but only because eventually it
is the whole idea of objective time which is "illusory". Subjective
time, I would say, cannot be illusory, nor can subjective pain be.




> since it assumes that I-now can have 1st person knowledge of
> I-yesterday or I-tomorrow, when in fact such knowledge is impossible
> except in a 3rd person way.


I disagree. I do have a first person account of I-yesterday, and some
first person feelings about possible first person feelings of myself
tomorrow, all of which are non describable in any third person way.
Again we could be in agreement here. If you want I have no doubt about
my "I-yesterday", even if I don't believe at all in some absolute third
person describable notion of "yesterday". But I do "feel" I-yesterday:
I cannot separate it from "I-now" and "I-tomorrow". This is completely
independent of the fact that I may well die in a second.



> I believe it is this confusion which leads to the apparent anomaly of
> 1st person indeterminacy in the face of 3rd person determinacy in
> duplication experiments.


I don't see any anomaly, to be sure. Only weirdness, relative to
probable prejudices.



> Let us assume as little as possible and make our theories as simple as
> possible. I *have* to accept that there is something special about my
> experiences at the moment which distinguish them from everyone else's
> experiences: this is the difference between the 1st person POV and the
> 3rd person POV.


OK, but just remember that in the UDA thought experiment, the first
person is almost defined by the content of a personal diary/memory. And
what makes those experiences personal here is that they are destroyed
together with the body during destructive teleportation or duplication.
But the memories refers, in the present, to subjective (first person)
past and future. We cannot have illusions about that, only about third
person extrapolation *from* that.




> It is tempting to say that my 1st person POV extends into the future
> and the past as well, explaining why I think of myself as a person
> persisting through time.

I would say it is in the nature of the first person to persist in
*subjective* time. I have more problem with (naive?) notion of time and
space. So again I would agree it is an "illusion" that "1-I" persists
through some notion of 3-time and 3-space, but somehow the first person
is inextricably linked to a notion of 1-time and 1-space. The illusion
would consist in believing in a sort of describable existence of myself
in some describable notion of absolute space-time.



> However, this latter hypothesis is unnecessary. It is enough to say
> that the 1st person POV is valid only in the present,


But what could that means? Which present? Certainly a lasting present:
it is part of my first person identity that I feel a sort of
"continuous" time, which gives sense to all my first person willingness
to to do anything. When I do a cup of coffee, I strongly believe that I
will drink and taste that very coffee: it is part of "me-doing coffee".
I would have the feeling to lie to myself taking this as an illusion,
again independently of the fact that I will "really" (in case that
means something) drink and taste that coffee.
I still think I agree with you, or that I understand what you say, but
in general what you call "illusory" is for me just living "imagery"
(just *hopefully* well founded). Only third person extrapolations can
be considered as being "really illusionary", but then, this just means
"false and hopefully third person refutable". Then it is science
(meaning doubts, a-la Descartes/Popper).




> and when I consider my future and past that is only 3rd person
> extrapolation.


I agree if you mean by "future" and "past" 3-future and 3-past. 1-past
and 1-future is not extrapolation thy are feelings continuously lived
in a lasting present. I can no more doubt of my feeling of past than I
can doubt of a headache (say). Even if time by itself does not exist at
all (which is the case with comp). The extrapolation would reside only
in some third person projection of that time, space, ... (I think we
agree, the problem could just be the term "illusion").



> What I consider myself to be as a person is then explained as the set
> of 1st person experiences related in a particular way,


OK. the word "related" is quite important here. One of the goal is to
isolate that relation. Technically this is done by finding the (modal)
logic of the (comp) first person and studying its Kripke or more
general "multiverse" structure.



> such as believing themselves to be moments in the life of a single
> individual, having memories or quasi-memories in common, and so on.
> If I split into two that presents no problem for the 3rd person POV
> (there are two instantiations of Stathis extant where before there was
> one) nor for the 1st person POV (each instantiation knows it is
> experiencing what it is experiencing as it is experiencing it).


OK.



> A problem does arise when I anticipate the split (which one will I
> become?) or look back at the split (*I* was the original!); there is
> no correct answer in these cases because it is based on 3rd person
> extrapolation of the 1st person POV, which in addition to its other
> failings assumes only a single entity can be extant at any one time
> (only a single 1st person exists by definition, but multiple 3rd
> persons can exist at the one time).


This is a little weird. You say there is no correct answer, and then
you give the comp-correct answer.
The first person is indeed just NOT first person-duplicable (unless
some added artificial telepathic trick, but in genral I talk only on
the usual simple teleportation or duplication).




> This is not to say that my mind can or should overcome [Lee Corbin
> disagrees on the "should"] the deeply ingrained belief or illusion
> that I am a unique, one-track individual living my life from start to
> finish,


Here you really talk about the third person extrapolation, so I agree
with you. But the first person is not deceive by its feeling of living
uniquely in time and space. It could be dangerous to say so, because it
leads to (materialism) eliminativism which eventually conclude that the
whole first person thing is an illusion. This leads to a deeply wrong
sense of "human"-irresponsibility. Well, it is a negation of the first
person. I can be sure it is wrong, as I bet you can too.




> which is why in symmetrical duplication experiments I anticipate that
> I will become one of the duplicates with equal probability.


So you follow at least the UDA up to the third step included.
(For possible others we refer to the eight steps presentation of UDA
summarized in the following slide (just one page PDF) and paper:
http://iridia.ulb.ac.be/~marchal/publications/SANE2004MARCHAL.pdf
http://iridia.ulb.ac.be/~marchal/publications/SANE2004MARCHAL.htm
(The paper is available in pdf too:
http://iridia.ulb.ac.be/~marchal/publications/SANE2004Slide.pdf)


> In asymmetrical duplication experiments with partial memory loss or
> merging, it becomes very difficult to know what to expect.


OK but the fourth step of UDA is just asymmetrical duplication without
memory loss.
I don't count the destruction of the original+its personal diary as a
memory loss, giving that the memory is thoroughly conserved in the
reconstitution (by the hypothesis + default assumptions on the
rightness of the substitution level and the reliability of the doctor's
work, etc.)
What about that?
Oh. I see you answer this below ...


>> All right then. Except that I am not sure I really agree with the idea
>> that the persisting "I" is an illusion. Here, it is hard for me not
>> taking account of the main UDA conclusion: the reversal
>> physics/bio/compscience/theology/numbers. So let me tell you what I
>> believe, accepting comp and the UDA reasoning: The persisting "I" is
>> not an illusion, or is less an illusion than its body or time itself.
>> What could also be an illusion is the feeling that "I" and "you" are
>> absolutely different, when the difference is only relative.
>
> See above. Perhaps "illusion" is not the right word. Is a motion
> picture an illusion? It is a series of still pictures presented in a
> particular way giving the effect of motion from the POV of a human
> observer; better to be descriptive than use words like illusion and
> delusion.


Yes. "illusion" is a dangerous word, especially with comp. "Illusion"
is the first person basic bread, and are real from its/her point of
view. The first person error (the real illusion) consists in its third
person extrapolation, from the movie or even from "real life".


> Some of the above is very much tied up with the way we use language,
> like the difference between saying there is motion on the screen or
> there is only the illusion of motion on the screen.


There is no 3-motion, but there is 1-motion. The first person really
perceives motion, it cannot even doubt it intellectually, even if she
believes there is no 3-motion at all here.
With comp, it will be highly undecidable that there is anything more
than numbers and their relations so that even "physical motion", even
though possible first person *plural* sharable one, is "illusionnary"
or let us say 3rd extrapolate. In that setting I use often the word
"dream" but it convey also that "wrong" aspect of the word "illusion".
The whole point is that comp forces those illusions/dreams to obey to
non trivial mathematical laws making them overlapping, glueing, etc.
The physical realities (should) emerge from that (UDA's last
conclusion).



> I falter at step 7 of the UDA as given in your 2004 SANE paper,
> especially from the point after "We are almost done..."


Perhaps you have not enough appreciate the importance of the invariance
of the first person experience when reconstitution delays are added. It
did help people to explicitly recall the delays in the drawing 5), 6)
7) (and 8)).
Unless I am deadly missing something, it seems to me that what follows
"We are almost done ..." can easily (?) be deduced from the six first
steps. My experience with people who got problems in the seventh step
is that they don't have really appreciate step 5).
It would help me if you could tell precisely where is the problem at
the end of step 7; so let me quote it:


<<We are almost done. Indeed, let us try a simple “physical experiment”
like dropping a pen. With comp, when we are in the state of going to
drop the pen, we are in a Turing emulable state.>>


All right? This follows directly from the comp hyp.



<<Our more probable consistent extension is undetermined by the 1-comp
indeterminacy on all the “reconstitution” of that similar states
appearing in UD* (the infinite trace of the UD).


All right? This follows from the definition of the UD. And the UD
exists once we assume Church Thesis, and UD* (the trace of the UD)
exists thanks to Arithmetical realsim. Rememeber I defiune comp by
mainly CT and AR (+ the "yes doctor").



This follows from 6, and the invariance of the uncertainty measure,
notably for the arbitrary delay---including the null one, and the
infinite set of states appearing with a arbitrarily large delay in the
running of the UD[14]. This gives a huge set. >>


All right? You almost just said exactly this in your today's
(29/june/2006) message to Brent Meeker.
And from this you can already conclude that comp entails a reversal
between physics and computer science/number theory. The next sentences
are there just for making easier the interface with the mathematical
interview of the lobian machine, which is needed only to make explicit
the manner we have to follow for extracting physics from computer
science.



<<It can be argued that finite computations are of measure null, and
that the only way to a measure on the states will consist in finding a
measure on the set of maximally complete computational history going
through those states, with obviously a rather hard to define
equivalence relation among computations. Still, we can show that those
(infinite) computations, as seen from some third person description of
UD*, correspond to maximally consistent extensions of our (hopefully)
actual consistent states. It is not necessary to be more precise here,
giving the non constructivism of the collection of those consistent
extensions, and the fact that we will make things utterly precise, by
directly interviewing a universal machine on those extensions, and this
by taking into account the 1/3 person point of view distinction. So, if
we grant a sufficiently robust universe, we are completely done:
physics, as the “correct” science for the concrete relative predictions
must be given by some measure on our consistent relative states.
Physics is, in principle reduced to a measure on the collection of
computational histories, as seen from some first person point of views.
We can say that in principle, physics has been reduced to computer
fundamental psychology. >>


Bruno

http://iridia.ulb.ac.be/~marchal/


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Received on Thu Jun 29 2006 - 09:06:48 PDT

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