On 31 Mar 2011, at 13:53, Stathis Papaioannou wrote:

On Thu, Mar 31, 2011 at 9:15 AM, Nick Prince
<nickmag.pri...@googlemail.com> wrote:
In Russell’s book there is a section on “Arguments against QTI”
And I want to put forward some issues arising from this.

It seems that (if MWI is true) we live in world(s) in which we appear
to live a finite, small lifetime of around 70 years.  From the many
discussions on this list, it also seems to me that, this is the single biggest argument (that I can understand) which points to the QTI being
false.  Unfortunately it appears that the whole ASSA/RSSA debate -
which might have been a candidate for clarifying the issue - turns out
to be a confusing (to me anyway) and polarising approach.

So is QTI false?

Russell does put forward a possible solution in his book. He suggests
the idea that as memory fades with dementia then perhaps the conscious
mind becomes so similar to that of a newborn - or even unborn - baby
that perhaps “a diminishing?” consciousness always finds an
appropriate route (in some branch) to avoid a cul de sac event.
(This is one possible form of the No Cul De Sac Conjecture =NCDSC)

To avoid the cul de sac event, there would surely have to be a
critical  stage whereby  consciousness diminishes and reaches a form
of cusp at the point of lapsing into non existence and thereby
requiring the necessity of an extension route or branch to another
consistent universe.  In short, from the third person POV, the person
dies but from the first person -(now primitive) consciousness – state,
there is rebirth.  I am thinking that before we get to the croaking
Amoeba there is a discontinuity in what we understand as consciousness
– at least the form that applies to the NCDSC.

Now if all this were to be the case, then maybe it says something very specific about the substrate on which consciousness runs. There would
be something special about the architecture which the substrate
employs to implement consciousness because it relies on a certain mode
of decay, facilitating the branching to a new born baby having an
appropriate structure (portal?) to secure a consistent extension of
the consciousness into  another branch.  Unless a computer could
simulate such a special substrate then it could not be used to
implement consciousness. This would mean that it would be wise to say
no to the Doctor! –  Comp might be false?

I followed you up until that paragraph. Why should the rebirth from a
no-consciousness state say anything about the substrate on which
consciousness runs? It matters only that there be some entity that
remembers being the entity that faded away for that entity to be
reborn. How that entity is implementedt and whether it is even
causally related to the first entity in any way is irrelevant.

I followed you up until the last sentence. How that entity is implemented and whether it is even causally related to the first entity in any way is irrelevant for the question of being reborn, OK, but for computing the measure, and thus deriving the laws of the most probable substrate with respect to which he is reborn (his physics), you have to take into account the most probable computational histories. The notion of cause emerges from that, and that is what makes its "rebirth" relatively stable for him, and not an harry Potter like sequence of luck. This makes the physical laws invariant for such "rebirth", although we might find ourself at different level or layers of some virtual reality of the future, so some apparent laws could be expected to change.

The Turing principle (p135 of David Deutsch’s book – “the Fabric of
Reality”) would imply that, a universal machine could simulate the
physical structure of brains in such a way so as to be able to act as
a medium whereby, if the above argument is possible, consistent
extensions of conscious physical observers (persons) could avoid cul
de sacs. But until we can understand the nature of what consciousness is, we are stumped as to how a computer can be programmed to implement
it.  However some alien civilizations may have known these techniques
for ages now, thereby perhaps explaining why we each have lived even
as long as we now perceive we have. A stronger statement would be that
if universal virtual reality generators are physically possible, then
they must be built somewhere in some universes!

But supposing the above (reincarnational) speculation was false in
some way. In that case, I have yet to see a convincing argument as to
how the the no cul de sac conjecture can be reconciled with people
living  to great ages.  Whatever sampling assumption is applied, the
facts are that we don’t typically see people reaching ages greater
than 100+ yrs). Therefore either QTI is false or  people just don’t
get old! Rather, the special physical conditions of death associated
with dementia or oxygen starvation of the brain, facilitate continued
extensions of consciousness by branching into worlds where we
supervene over new born babies (or something – animals, aliens?) -
accidental deaths of people of any “normal ages” we can think about
could of course be accommodated by the NCDSC).

That we don't see extremely old people is consistent with QTI, since
from the third person perspective rare events such as living to a
great age happen only rarely. However, from the first person
perspective you will live to a great age, and this will happen in the
most probable way, even if it is improbable in absolute (third person)

It is here that if we apply Bayes' theorem (like in the Doomday argument), we should be astonished not being already very old (from our first person perspective). But Bayes cannot be applied in this setting, as we have already discussed a lot in the past.

Bruno Marchal

The mechanics of such  reincarnational transitions would be
interesting to speculate about since I see this as the only way out
for a QTI.

Nick Prince

Stathis Papaioannou


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