I think what Saibal was referring to can be illustrated by a device used
quite often in science fiction, where a person's mind is "backed up" at time
t1, then restored from backup when the person dies at time t2. The effect
for the person is exactly the same as if he had not died at t2, but instead
lost all memory of what had happened to him between t1 and t2. The
situation in the multiverse differs in that (a) the "backup" is happening
continually; (b) the "backup" is run immediately on being made, rather than
waiting for a particular event; and (c) the period of effective memory loss
involves the entire world rather than the person alone, so that he cannot
access any record of his death after being restored from backup. (b) and (c)
should not make a substantive difference, and (a) should be an advantage,
since it means that in the multiverse, the period of memory loss will never
be more than a moment, even if some terminal situation does arise from which
there is no escape. Given that in some branch of the multiverse the Governor
grants clemency a fraction of a second before the poison enters Tookie's
vein, this is equivalent to a fraction of a second of memory loss for the
version of Tookie in the branches where the execution goes ahead.
Having said that, I'm still unclear as to why you think such situations of
no escape might actually arise in the multiverse. In order for Tookie to
survive the lethal injection, or even a direct nuclear hit for that matter,
it isn't even necessary to find some physically possible means of escape.
All that is necessary, as you say, is that "observer moments for Tookie
exist which include the memories of his having received the lethal
injection, but not of dying as a result". Now, surely you can think of
possible, albeit unlikely, ways in which this might happen. For example,
benevolent alien scientists opposed to capital punishment probe Tookie with
neutrino beams at the moment of death, store the information, then use it
later to either physically resurrect him or just run a copy of his mind in
virtual reality on a computer network. That would involve a "causal link"
between the pre- and post-execution Tookie. But how would Tookie know the
difference if he were resurrected non-causally? For example, what if the
requisite post-execution observer moments came about in the alien computer
network not because the scientists input the specific data, but as the
result of an algorithm that explored all possible, or a random subset of,
human-type sentient programs? Surely the significant thing is that there be
some post-execution Tookie OM, not how that OM comes about. Of course, such
OMs are *far* more likely to come about if there is some physical, causal
process to bring them about, just as someone who tries to log onto my
computer account is far more likely to succeed if he somehow finds out my
username and password. But if the state of California manages to destroy all
the physical/causal processes allowing Tookie to survive and all that is
left is the equivalent of trying usernames and passwords at random, the
multiverse will not run out of time or patience before the correct
combination comes up. As discussed in my previous post, this is certain
because the number of possible brain states (hence mental states) is finite,
as long as the size of your brain remains finite.
In summary: if you are Tookie and the MWI is true, you are unlikely to find
yourself living in a branch which leads to your execution in the first
place. If you do find yourself living in a seemingly terminal branch,
something will happen at the last possible moment to save you. If nothing
happens to save you, the multiverse will effectively back up your mind so
that your death would only constitute the subjective equivalent of the
tiniest amount of memory loss. And if even this amount of memory loss is
unacceptable to you, the multiverse has more than enough resources to
guarantee that somewhere, sometime a post-execution Tookie with every memory
intact will rise again.
Jonathan Corgan writes:
Saibal Mitra wrote:
> To me it seems that the notion of ''successor'' has to break down at
> where the observer can die. The Tookies that are the most similar to the
> Tookie who got executed are the ones who got clemency. There is no
> reason why these Tookies should be excluded as ''successors''. They miss
> part of their memories about things that happened after clemency was
> Instead of those memories they have other memories. We forget things all
> time. Sometimes we remember things that didn't really happen. So, we
> for information loss anyway. My point is then that we should forget
> all of the information contained in the OM and just sample from the
> set of OMs.
(After being away for a couple weeks, I'd like to follow up with yours
and others replies.)
I find this line of argument hard to follow. I think where we differ is
that I assume there must be some physical causality connecting observer
That is, if a person is in physical state A and is experiencing state
E(A), then their next subjective moment E(B) must have some connected,
causal path between physical state A and physical state B. This
reasoning makes the materialist assumption that subjective experience E
is entirely defined by the physical state of the observer.
According to MWI, physical state A actually evolves into a superposition
of discrete physical states B, each with a different "density" or
"measure." So, by the logic of the previous paragraph, subjective
experience E(A) must evolve into a superposition of discrete Es, each a
function of the particular discrete physical state B it arises from, and
each with a particular measure.
Some subset of this superposition of physical states B, however, do not
support the creation of subjective experience (say, where the person has
died.) So some proportion of E(B)'s are null.
So my original question about "what is happening to Tookie now" can be
rephrased as the following thought experiment:
Physical state A is Tookie lying on a gurney, experiencing E(A), which
is getting injected with lethal toxin by the State of California.
Clearly, the vast majority of the elements of superposition of states B
which follow the execution are with him being dead, and do not give rise
to any subjective experience at all.
What are the possibilities for causally connected physical states which
don't involve his death? Which B's exist which continue to give rise to
In other words, which observer moments for Tookie exist which include
the memories of his having received the lethal injection, but not of
dying as a result?
Does there have to be any at all? QTI says yes, there must be, and no
matter how unlikely--there is always escape in some form. What was
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