>From: "Jacques Mallah" <[EMAIL PROTECTED]>
>Subject: Re: FIN Again (was: Re: James Higgo)
>Date: Thu, 30 Aug 2001 17:51:46 -0400
>>From: "Jesse Mazer" <[EMAIL PROTECTED]>
>>I don't understand your objection. It seems to me that it is perfectly
>>coherent to imagine a TOE which includes both a universal "objective"
>>measure on the set of all observer-moments and also a relative conditional
>>probability which tells me what the probability is I'll have experience B
>>in the future if I'm having experience A right now.
>    "You" is just a matter of definition.  As for the conditional effective
>probability of an observation with characteristics A given that it includes
>characteristics B, p(A|B), that is automatically defined as p(A|B) = M(A 
>B) / M(B).  There is no room to have a rival "relative conditional
>probability".  (E.g. A = "I think I'm in the USA at 12:00 today", B="I 
>I'm Bob".)

Well, I hope you'd agree that which observer-moment I am right now is not a 
"matter of definition," but a matter of fact. My opinion is that the global 
measure on all observer-moments is not telling us something like the "number 
of physical instantiations" of each one, but rather the probability of 
*being* one particular observer-moment vs. some other one. I would be 
interested to hear what you think the measure means, though, since my 
version seems to require first-person facts which are separate from 
third-person facts (i.e., which observer-moment *I* am).

In any case, I'm pretty sure there's room in a TOE for a "conditional 
probability" which would not be directly deducible from the global 
probability distribution. Suppose I have a large population of individuals, 
and I survey them on various personal characteristics, like height, IQ, age, 
etc. Using the survey results I can create a global probability function 
which tells me, for example, what the likelihood is that a random individual 
is more than 5 feet tall. But If I then want to find out the conditional 
probability that a given individual over 5 feet tall weighs more than 150 
pounds, there is no way to deduce this directly given only the global 
probability distribution. In this example it may be that p(A|B) = M(A and B) 
/ M(B), but the point is that M(A and B) cannot be found simply by knowing 
M(A) and M(B).

And a TOE could conceivably work other ways too. Suppose we have a large 
number of interconnected bodies of water, each flowing into one another at a 
constant rate so that the total amoung of water in any part stays constant 
over time. In that case you could have something like a "global measure" 
which would tell you the probability that a randomly selected water molecule 
will be found in a given body of water at a given time, but also a kind of 
conditional probability that a water molecule currently in river A will 
later be found in any one of the various other rivers that river A branches 
into. This would approximate the idea that my consciousness is in some sense 
"flowing" between different experiences, splitting and merging as it goes. 
Just as the path of a given molecule is determined by the geographical 
relationships between the various bodies of water, so the path of my 
conscious experience might be determined by some measure of the "continuity" 
between different observer-moments...even though an observer-moment 
corresponding to my brain 5 seconds from now and another one corresponding 
to your own brain at this very moment might have equal *global* measure, I 
would presumably be much more likely to flow into a future observer-moment 
which is more similar to my current one.

Most generally, we can imagine that a TOE defines both a global measure on 
individual observer-moments, but also a "conditional measure" on ordered 
pairs of observer-moments, or perhaps longer ordered chains. There would 
probably be some kind of mathematical relation between the two types of 
measure, but it wouldn't necessarily have to be of the form p(A|B) = M(A and 
B) / M(B) as you said. Do you see anything inherently contradictory about 
this idea?

>>self-sampling assumption--what does it mean to say that "I" should reason
>>as if I had an equal probability of being any one of all possible
>    It means - and I admit it does take a little thought here - _I want to
>follow a guessing procedure that, in general, maximizes the fraction of
>those people (who use that procedure) who get the right guess_.  (Why would
>I want a more error-prone method?)  So I use Bayesian reasoning with the
>best prior available, the uniform one on observer-moments, which maximizes
>the fraction of observer-moments who guess right.  No soul-hopping in that
>reasoning, I assure you.

I'm not sure it's possible to take a third-person perspective on the 
self-sampling assumption. For one thing, the reasoning only works if I 
assume *my* observer-moment is randomly selected--I can't use anyone else's 
or I may get incorrect results, as if I reasoned from Adam and Eve's point 
of view in the doomsday argument. Then there is what Nick Bostrom calls the 
"problem of the reference class," and I think there is a very good case to 
be made that the problem can only be solved by making reference to some sort 
of objective measure of  the "consciousness level" of a particular 
observer-moment. For example, suppose I find that I was created as one of 
two "batches" of humans, the first batch containing 950 members and the 
second containing only 50. One batch is all-male and the other is 
all-female, and I know that which batch is which sex was determined by a 
coinflip, so that a third-person observer would say there is a 50% chance 
that the large batch is the male batch. However, since I observe myself to 
be a male, I use the self-sampling assumption to reason that there is 
actually a 95% chance that the large batch was all-male, simply because I'm 
assuming that I'm as likely to be any human as any other, and 95% of the 
humans were members of the large batch.

All right so far. But suppose I now find out that one of the two batches was 
genetically engineered to lack a brain, having no consciousness whatsoever? 
Or, if you prefer, suppose that one batch is not made of real humans at all, 
but just marble statues of them. Can I still assume I am as likely to be any 
individual as any other? I don't think so--I think some kind of "anthropic 
principle" must come into play here, guaranteeing that I will be a conscious 
individual rather than an unconscious one. So, even if the small-batch was 
the all-male one, I would still be guaranteed to find myself a male, simply 
because all the "females" in this experiment are going to totally lack 
consciousness. It's just the same as how I can't assume I'm "randomly 
sampled" from the set of all computations being implemented in the universe, 
because the vast majority of computations, associated with things like the 
random collisions of gas molecules in a nebula, will not lead to any 
high-level conscious experiences...only the very rare ones associated with 
biological brains which have evolved on planets with just the right 
conditions will have these sorts of experiences (or so I'd assume, anyway). 
Again, the anthropic principle must be taken into account.

I think this should be a matter of degree, rather than an all-or-nothing 
affair. I think other animals, at least other mammals and birds, almost 
certainly have some kind of high-level conscious experience, so there is 
"something it is like" to be them, but I don't think I should reason as if I 
was randomly sampled from the set of all these animals, either. Indeed, I 
don't think it's just a lucky break that I find myself to be a member of 
what is probably the most intelligent species that has ever existed on 
planet earth, despite the fact that the number of animals who have ever 
lived probably vastly outweighs the number of homo sapiens who have ever 
lived. I think some sort of graded anthropic principle is likely to be 
responsible here...the usual self-sampling assumption perhaps needs to be 
replaced by some kind of weighted self-sampling assumption, with the 
"weights" on an observer-moment having something to do with the complexity 
of the consciousness involved. Indeed, I think it would be particularly 
elegant if the whole global measure function turned out to be nothing but 
this sort of weighted self-sampling assumption, although the weights would 
probably have to be determined by more than *just* the level of 
consciousness (after all, an observer-moment experiencing a white rabbit 
could be just as complex as a 'normal' one). In other words, I think a TOE 
should incorporate a "theory of the anthropic principle" rather than just 
adding it onto a sort of global "physical" measure as in theories like Max 
Tegmark's. The anthropic principle/physical measure distinction seems to me 
to be another version of the old mind/body duality, and it would be nice if 
a TOE could erase this distinction.

So I guess I should repeat the question, when you talk about a global 
measure on all observer-moments, what do you think this measure means? Does 
it just represent the "number of instantiations" in the multiverse, so that 
if the vast majority of observer-moments/computations turned out to be of a 
very simple nature, we might need to make additional recourse to the 
anthropic principle to explain why we find ourselves to be experiencing 
these particularly complex type of observer-moments? Or do you think, as I 
do, that the global measure tells us the actual probability that "my" 
current experience will be a given observer-moment, and in that case do you 
agree that the global measure function must already take into account 
something along the lines of the anthropic principle?

>>if I am about to step into a machine that will replicate one copy of me in
>>heaven and one copy in hell, then as I step into the imaging chamber I 
>>be in suspense about where I will find myself a moment from now, and if 
>>conditional probability of each possible future observer-moment is 50%
>>given my current observer-moment, then I will interpret that as a 50/50
>>chance that I'm about to experience torture or bliss.
>    That depends on the definition of "you".  In any case, one copy will be
>happy (the one partying with the succubi in hell) and the other will be sad
>(the one stuck hanging out with Christians).  So your utility function
>should be about even.  I assume you'd care about both future copies at that

Well, you're assuming that reality itself has no opinion on the definition 
of "me," that it all depends on my own choice of utility function. Likewise, 
perhaps someone might have a TOE in which there is no "objective" global 
measure on the set of all observer-moments, that each observer-moment would 
have his own measure defined by what he believes to be real.

But I think that in both cases the TOE should give me an answer which does 
not depend on my own preferences--as Phillip K. Dick once said, "reality is 
that which, when you stop believing in it, doesn't go away." I don't think I 
could "save myself" from a hellish fate simply be redefining my utility 
function so that only those copies which go to heaven are defined as 
"me"--whether I find myself in heaven or hell seems to be something imposed 
on me by external reality, unless the flow of consciousness is a complete 
illusion. I talked about this question in an earlier post called "3 possible 
views of consciousness:"


These were the 3 I mentioned:

>1.  Consciousness is not "real"--our decision to call a system "conscious" 
>or not is based only on subjective aesthetic criteria, like "cuteness" 
>(Daniel Dennett's example).  The only facts about reality are third-person 
>facts, in this view.
>2.  Consciousness is real, but the feeling of continuity of consciousness 
>over time (the 'flow of related thoughts in time' above) is not.  In this 
>view, only moments of experience exist, but nothing flows between these 
>3.  Consciousness is real, and so is continuity of consciousness over time. 
>  Proponents of this view may still believe that identity can split or 
>merge though (think of many-worlds, or replicator experiments).

Presumably you'd choose either 1 or 2, although I'm not quite sure which. 
But do you think view #3 is "crazy," or is it just quantum immortality 
specifically that you find crazy? It would be possible to believe in #3 
without believing in quantum immortality, of course...I do think that once 
you accept #3, as well as the "splitting" and "merging" of 
consciousness-streams, then are some thought-experiments which make quantum 
immortality very plausible. But they're only plausible if you already find 
view #3 to be plausible in the first place.

>>Surely you agree that there is nothing *mathematically* incoherent about
>>defining both absolute and conditional probability measures on the set of
>>all observer-moments. So what's your basis for calling the idea "crazy?"
>    I've explained that in other posts, but as you see, the idea is indeed
>mathematically incoherent - unless you just mean the conditional effective
>probability which a measure distribution defines by definition.  And _that_
>one, of course, leads to a finite expectation value for ones's observed age
>(that is, no immortality).

The "expectation value" is a problem, but as I said it's possible to accept 
#3 without accepting quantum immortality. For example, there could be a 
"null observer-moment" (death) which any given observer-moment has a small 
probability of becoming at any given time, and this probability could become 
large given enough time. Another interesting possibility is that whatever 
"conditional probability" we choose will be nonzero for *any* pair of 
observer-moments, so that there is some tiny probability that my next 
observer-moment will be completely unlike my current one--in situations 
where the probability of my physical death is large (like observing myself 
falling off a cliff), perhaps the combined conditional probability of my 
next moment being fairly similar to my current one is smaller than the 
combined conditional probability of a dissimilar next moment, so that I may 
suddenly find myself waking up from a dream of falling as a totally 
different person in a different region of the multiverse. In this way my 
conscious experience could be infinite even if at any given time I find 
myself as a finite organism with a finite memory.

Finally, if conditional measure and global measure mutually determine each 
other in some way, there might be a way in which "young" observer-moments 
could have greater global measure than "old" ones. Imagine an experiment 
where I am duplicated, as in Bruno Marchal's example, once in Moscow and 
once in Washington. Then a year later, if a democrat wins the U.S. 
presidency, the Washington twin will be duplicated 1000 times; if a 
republican wins the presidency, the Moscow twin will be duplicated 1000 
times. Even though this subsequent duplication happens a year after the 
original Moscow/Washington split, I think it could have an effect on my 
original first-person probability of finding myself in Moscow vs. Washington 
(since after all this is done, 1000 out of 1001 descendants of the original 
person will remember having ended up in the city corresponding to the future 
president)...we might then have the strange effect that I would have a 
pretty good idea of who was going to win the presidency a year from now 
based on whether I found myself in Washington or Moscow, even though this 
prophecy would be useless to everyone else since they'd have no way of 
knowing which twin has a lower measure/probability of being experienced. 
What this might mean is that the global measure on a particular-observer 
moment would be found by doing some sort of "path integral" over all 
possible future histories, which would perhaps be weighed both by their 
internal consistency (determined by the conditional measure--a history where 
my experience leaps around between radically different observer-moments 
might contribute less than a more 'seamless one') and by their objective 
probability (determined by the global measure of all the constintuent 
observer-moments, which would hopefully make white rabbit experiences very 
unlikely). Now, there's obviously something a bit circular about this, since 
it would involve finding the "objective probability" of experiencing a 
particular observer-moment by doing something like an integral over all 
possible first-person histories containing that observer-moment, and these 
histories would be weighted by internal consistency *and* the "objective 
probability" of all the other experiences in all these possible histories. 
But perhaps this would allow you to bootstrap a unique global probability 
distribution into existence, like solving a large set of simultaneous 
equations to get unique values for each variable.

If the global probability distribution depends on the possible future 
histories of each observer-moment, then it might change how we should think 
of quantum immortality. For instance, instead of the immortality guarantee 
only "kicking in" at the last possible moment (as the guillotine is 
dropping, say), we might have a situation where the most likely 
observer-moments are precisely those that can most "reasonably" be expected 
to survive long periods of time (so that I'd be less likely to go to the 
guillotine in the first place). Just as there may be a whiff of the 
anthropic principle in the fact that I find myself to be a human rather than 
one of the many other animals which has ever lived on earth, I think 
something like the anthropic principle may also be involved in the fact that 
I find myself at this particular point in human history, on the verge of a 
possible "technological singularity" which could make my indefinite survival 
seem entirely natural (see http://www.aleph.se/Trans/Global/Singularity/ ). 
And beings who are among the first to upload having their memories most 
widely distributed in the future evolution of a cybercivilization spreading 
throughout the universe, since they will have the most time to "expand their 
minds", make large numbers of copies of themselves, etc. Thus, "young" 
observer-moments on the cusp of the singularity might have much higher 
global measure, just as the twin about to be duplicated 1000 times might 
have had higher global measure than any of his subsequent "descendents." 
Alternately, even if you ignore the possibility of such a singularity, if 
you think of the MWI in terms of "splitting histories" then young 
observer-moments might be more likely for similar reasons.

So, there are a variety of ways I can imagine solving the "expected age" 
problem without having to throw out quantum immortality. I expect you'll 
find them all somewhat crazy...that's why, for now, I'd rather focus on the 
more general question of whether you think it's completely impossible that 
the correct TOE would make continuity of consciousness into something 
"objective" rather than something defined only by our own choices about 
utility functions. I don't entirely rule out the possibility that continuity 
of consciousness is a kind of illusion, but I still don't see how you can 
have grounds to be sure that it is.


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