Re: zombie wives

From: Christopher Maloney <>
Date: Wed, 18 Aug 1999 22:37:38 -0400

Sorry it's taken me a while to reply to this post.

"Jacques M. Mallah" wrote:
> On Fri, 13 Aug 1999, Christopher Maloney wrote:
> >
> > I agree that the concept "that one's measure is somehow distributed
> > among the so called computational continuations of one's brain activity"
> > leads inevitably to the concept of near-zombies. The description of
> > making a million copies of one person is a good illustration. Each of
> > those copies has only a one millionth chance of "being" the original
> > person, so we should not be as concerned when one of those dies as
> > when someone else, who has never been copied, dies. But is this a
> > refutation of the concept, by reductio-ad-absurdum? I don't think so.
> It is absurd to me and hopefully will be to the others. I think
> you are not being objective since you usually find zombies absurd.

I should have qualified my zombie view in the post before, but I forgot.
If you re-read it, you'll notice that I always used the term "near-
zombies". I certainly do find the concept of zombies absurd. But "near-
zombies", as I was using the term, are physical SAS's that have a very
low measure of existence. That is, any random conscious entity would
have a low probability of finding itself to be that one relative to

But "near-zombies" are not the same as zombies -- there is a qualitative
difference between low measure and not conscious (zero measure). I tend
to agree with Russell that it's difficult to see what measure has to do
with consciousness.

> > I want to clarify one thing, though, in Jacques' post:
> >
> > "Jacques M. Mallah" wrote:
> > >
> > > On Fri, 13 Aug 1999, Russell Standish wrote:
> > > > > referring to
> > > > > > t0 |
> > > > > > |
> > > > > > t1 T / \ H
> > > > > > / \
> > > > > > t2 / / \
> > > > > > | | \
> > > > > > t3 Y R B
> > > > >
> > > > > Assume that all three branches occur (two copying events).
> >
> > If there are two copying events, then there is no place for a coin
> > toss to enter into the experiment, so the 'T' and 'H' should be
> > erased from the diagram. The point is still made that, at time t0,
> > Jane would figure:
> > P(left branch, t1) = 1/2, P(right branch, t1) = 1/2
> > P(Y, t3) = 1/2, P(R, t3) = 1/4, P(B, t3) = 1/4
> >
> > Which would imply that the two copies of her that saw red and blue
> > would be less likely to be the same Jane at t0, so in some sense,
> > they would be less human, you might say.
> In the QS claim, that is. T and H can still label the branches.

Okay as long as T and H are just labels, and there is no coin toss,

> The two experiments are actually rather different and I should
> have made the distiction clearer in my post. I assume you refer below to
> the case with two copying events.

No, I thought I was very clear. All of my six "options" are alternative
ways of interpreting the original experiment, with a coin toss, and one
copying event if the toss lands heads. There may be a problem with
terminology here, because if you assume the MWI, then the coin toss is
a copy event. I do usually assume MWI, so I may have confused things.

> > 3. Subjective probabilities can be computed, but the assumption
> > that consciousness can "flow" to a continuation independent of
> > time or space is flawed.
> >
> > This, I think, is Jacques' point of
> > view. Though he didn't state it, I would guess that he would
> > say that
> > P(H, t1) = P(H, t2) = P(H, t3) = 1/2,
> > and that the original Jane would necessarily feel herself to
> > continue along with her original body. That is, if, in the
> > above diagram, at the copying event after Jane sees Heads, we
> > assume that the original Jane is the one who is shown the Red
> > card, then Jane at t1 would say
> > P(R) = 1, P(B) = 0
> > The copy of Jane who sees the blue card is a new person, who
> > was just "born" at the instant the copy was made, even though
> > she has all the same memories as the original.
> That is NOT my position, though of course I think 'consciousness
> flowing to and being distributed among continuations' is nonsense. I make
> no distinction between a copy and the original; 'identity' is not a
> fundamental concept. Each has the same amount of measure. For practical
> purposes the distinction is useful, however. It's just a matter of
> terminology in the practical use.

Then I wish you would describe what you do believe. I am stymied in my
attempts to make sense of it, and I have tried.

Consciousness "flowing" is perhaps a bad image. I mean nothing more than
that certain observer moments are related by some sort of identity function
to other observer moments.

> > 4. Subjective probabilities can be computed on the basis of the
> > Strong SSA, and we get
> > P(H, t1) = 1/2
> > P(H, t2) = P(H, t3) = 2/3
> > If this is the case, then I think we have to throw Tegmark's
> > scheme using Bayesian statistics out the window. This option
> > has severe metaphysical problems, though, in my opinion.
> I don't know what you mean by the above paragraph, but the
> effective probabilities are correct if there are two copying events. The
> SSA is the right way to do Bayesian calculations.
> If the T-H split represented a non-MWI coin toss and was a one
> time event, then P(H,t3) = 1/2. In practice those conditions would be
> impossible to achieve even without the MWI of QM (e.g. in an infinite
> universe) and P(H,t3) = 2/3.

It's very simple, although I guess I haven't written it out in gory
detail before. Tegmark's formula "for any mutually exclusive and
collectively exhaustive set of possibilities Bi, the probability of
an event A is given by
    P(A) = Sum over i [ P(A|Bi) P(Bi) ]

I want to computer P(H, t3). Let B1 be (H, t1) and B2 be (T, t1), then

    P(H, t3) = P(H,t3 | H,t1) P(H,t1) + P(H,t3 | T,t1) P(T,t1)

We assume in this option (4) that P(H,t1) = P(T,t1) = 1/2. Now, I
maintain, and I really don't see how it could be otherwise, that

    P(H,t3 | H,t1) = 1 and
    P(H,t3 | T,t1) = 0.

Some people have claimed that these relations do not hold, but I don't
see what they could possibly be talking about. These statements say
nothing more than that my memories are consistent -- that I can expect
them to remain constant. If we abandon that, then all hope is lost!
I wish those who claim this (Hal?, Wei?) would explain themselves better.

So, anyway, we get P(H,t3) = 1/2 by Tegmark's formula.

> > 6. Subjective probabilities can be computed, and we should expect
> > the nonsensical results
> > P(H, t1) = 2/3
> > P(H, t2) = P(H, t3) = 2/3
> >
> > This is what I believe is probably true. I think that there
> > must be a sort of "reverse causality" at work, which would
> > increase the measure of the right branch of Jane at time t1
> > (the branch that sees heads, but before the copy is made).
> Nonsense.


> > This still has Jacques' problem of allowing pseudo-zombies.
> > If we switch to Jacques' example and assume two copying events,
> > then the Jane on the left branch, at time t1, would have less
> > measure than the Jane on the right (note the contrast between
> > this result and the previous, where the Janes that were the
> > product of the second copying operation were accorded less
> > measure).
> >
> > But I don't see this as a problem. What I'm suggesting is that
> > each human alive today has a varying amount of "measure". It's
> > incorrect to assume that each person, when they are born, is
> > given a single "measure unit". By my scheme, a person with a
> > terminal illness with only a few days to live would have a
> > very small measure of existence, relative to others.
> Huh? This seems inconsistent with QS and the specifics aren't
> there.

This is my "near-zombie". We should not expect to find ourselves in the
body of someone about to die. We should not expect to land in the
hospital any time soon with a brain tumor and only a few days to live.

Now, note that this is consistent with QS. Just because the person
doesn't have a strong likelihood of survival, he or she does have a
non-vanishing likelihood, and will, therefore, necessarily find him
or herself surviving, by some extremely unlikely means. That's why
there's no such thing as a true zombie -- which would equate to
a conscious entity with a zero chance of continuing.

> > I can't help wondering, often, why I find myself to be the
> > particular human I am. Do you others wonder this?
> You are arrogant. I am not a typical human but see no reason to
> suspect I could not be a randomly selected human.

Tut tut tut. Why is it arrogant to wonder? The whole concept of the
SSA is about wondering why we are who we are.

> > One thought
> > I've had (please don't laugh at me too badly) is that the fact
> > that I have a pretty poor memory might be significant. If I
> > had a better memory, then my measure would be less, because
> > fewer universes could have given rise to me. Of course, this
> > reasoning probably won't work for you, but that doesn't make it
> > any less valid from my perspective, which is the only one I
> > have.
> Well I hate (giggle?) to say it but that sounds stupid. If you
> remember something non-random, that shouldn't cut your measure. If you
> remember a random bit, it cuts the total measure of each type of you in
> half but now there are twice as many types. By total measure I mean, as
> always, the number, so this is consistent with the SSA and leads to no
> zombies.

But you said it yourself, if I remember a random bit, "it cuts the total
measure of each type of [me] in half." I don't know what you mean by
"type". I'd say it cuts the measure of me in half. That's exactly my

> > I came to believe in this "reverse causality" while pondering
> > the QS project I wrote about before. I started to expect that
> > things would crop up in my way to prevent my being able to
> > complete the project, before it came to fruition. It didn't
> > (and it still doesn't) make sense to me that the measure of all
> > my branches should be unaffected until the very instant that I
> > carry out the experiment. Because if the assumption that I'll
> > be alive after the experiment date is correct, then I can expect
> > to have memories at that time of somehow having escaped. And
> > I should, in general, expect to have a memory of "the most
> > likely" escape route, or of one of the most likely ones, if there
> > are several that are near-equally likely.
> >
> > But how can one reconcile that with the concept of continuity of
> > consciousness from moment to moment? Only if there is a reverse
> > causality at work.
> >
> > This theory has significant and testable implications. Viz: we
> > should expect to find ourselves in a universe that will allow us
> > to live forever. I.e. this leads directly to the requirement
> > that the FAP is true. Just consider if time t1 and t2 are
> > separated by a larger and larger time span. Consider also that
> > those branches in which we cease to exist also tend to decrease
> > the measure of all the observer-moments in previous subjective
> > time.
> >
> > Basically, the measure of our observer-moments at the next
> > instant in subjective time are weighted as the number of continous
> > paths from that observer-moment to the "Omega-point". This is
> > my crackpot theory. Though it's certainly hard to justify on the
> > basis of the SSA on a moment-by-moment basis (the Strong SSA), I
> > haven't yet found anything that contradicts it. I know that's
> > not good enough, but anyway I find it the most satisfying
> > result of the above thought experiment. All the other possibilities
> > are problematic.
> The Omega Point CRAP is disproven because the universe is open.
> (CRAP=causally retroactive anthropic principle)

Cute! But I thing the jury is still out. I probably shouldn't use the
term "Omega-Point", since that refers to a specific theory of the infinite
future evolution of the universe. I sometimes use it to refer in general
to the infinite future in which life continues.

> - - - - - - -
> Jacques Mallah (
> Graduate Student / Many Worlder / Devil's Advocate
> "I know what no one else knows" - 'Runaway Train', Soul Asylum
> My URL:

Chris Maloney
"Donuts are so sweet and tasty."
-- Homer Simpson
Received on Wed Aug 18 1999 - 19:58:01 PDT

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