>
>
>
> Russell Standish wrote:
> >
> > >
> > > 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
> > > think Hal was saying, in his post, either this option, or
> > > option 1 above, but I'm not sure.
> > >
> > > 5. Subjective probabilities can be computed, and we should expect
> > > the common-sense results
> > > P(H, t1) = 1/2
> > > P(H, t2) = P(H, t3) = 1/2
> > >
> > > It's a fair coin, after all, right?
> > > I think this gets Gilles' and Bruno's vote (and Russell's?)
> > >
> > > 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
> > >
> >
> > If the probabilities can be computed, then compute them. I have
> > computed the probabilities as being 1/2,1/2. If you compute them as
> > 1/3,2/3, then you need to advance a similar computation, and then for
> > good measure, show me where I erred. Probability calculations are
> > notorious for their subtleties, so I won't take offence at being shown
> > wrong. At present, the only argument I can see that gives the
> > probabilities as 1/3,2/3 is the one based on the strong SSA - (your
> > point 4) - an assumption that I reject.
>
> Clearly there is not enough information to simply "compute" the
> probabilities from Jane's subjective perspective, without making
> some additional assumptions. In your computation, you assume that
> the measure of each branch is unaffected by its future evolution.
True - but I think this is currently a pretty fair assumption.
>
>
> > A reverse causality type of argument would assume that you would never
> > enter branches that have no escape routes. I have toyed with this
> > idea, but reject it - principally because I have yet to see an example
> > of a branch with no escape route, so in essence it becomes
> > meaningless
>
> This makes no sense to me. Let's rewind it -- You have yet to see a
> branch with no escape route. Fine, I haven't either. Let's assume there
> are none. The reverse causality argument would assume that you never
> enter branches that have no escape routes. Fine, we've just assumed that
> there are none. So what's the problem?
>
>
> >, but if there were such brances - my belief in foward
> > causality is so strong, I would prefer to question quantum
> > immortality, than to invoke reverse causality as a way of salvaging
> > QI.
>
> Yes, I guess I've been trying to make the point that QTI implies reverse
> causality. I think it does.
>
Yes - but only if cul-de-sac branches exist. My point is that QTI is
not proven, and shouln't be assumed to be true. Existence of
cul-de-sac branches + absence of reverse causality would imply QTI is
false.
>
>
> --
> Chris Maloney
> http://www.chrismaloney.com
>
> "Donuts are so sweet and tasty."
> -- Homer Simpson
>
>
----------------------------------------------------------------------------
Dr. Russell Standish Director
High Performance Computing Support Unit,
University of NSW Phone 9385 6967
Sydney 2052 Fax 9385 6965
Australia R.Standish.domain.name.hidden
Room 2075, Red Centre
http://parallel.hpc.unsw.edu.au/rks
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Received on Thu Aug 19 1999 - 17:33:25 PDT