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.
> 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.
--
Chris Maloney
http://www.chrismaloney.com
"Donuts are so sweet and tasty."
-- Homer Simpson
Received on Wed Aug 18 1999 - 19:57:56 PDT