>From: "Charles Goodwin" <cgoodwin.domain.name.hidden>
>[Jacques Mallah wrote]
> > But there's one exception: your brain can only hold a limited amount
>of information. So it's possible to be too old to remember how old you
>are. *Only if you are that old, do you have a right to not reject FIN on
>these grounds.* Are you that old?
>
>Yeah, that's one of my objections to QTI. Although perhaps add-on memory
>chips will become available one day :-)
OK. (And even if the chips become available, you'd probably only be
able to add a finite # before collapsing into a black hole.)
> > Right. Do you think you are in an infinitesimal
> > fraction, or in a typical fraction?
>
>Infinitesimal, if QTI is correct, otherwise fairly typical. Assuming QTI is
>correct and ignoring any other objections to it, it's *possible* for me to
>be in an infinitesimal fraction - in fact it's necessary.
Right - which is why Bayesian reasoning falsifies FIN, but only with
100% reliability as opposed to complete reliability.
>but according to QTI I *must* pass through a phase when I see the unlikely
>bits, no matter how unlikely it is that a typical moment will fall into
>that phase. Even if I later spend 99.9999999999999999999....% of my
>observer moments seeing the stars going out one by one, there still has to
>be that starting point!
Right, again, that's why the reliability is just 100%.
>My (ahem) point is, though, that none of us ARE at a typical point (again,
>assuming QTI). In fact we're in a very atypical point, just as the "era of
>stars" might be a very atypical point in the history of the universe - but
>it's a point we (or the universe) HAVE TO PASS THROUGH to reach more
>typical points (e.g. very old, no stars left...). Hence it's consistent
>with QTI that we find ourselves passing through this point...
Right, consistent with it but only 0% of the time, hence the Bayesian
argument is to put 0 credence in the FIN rather than strictly no credence.
>I'm not arguing for QTI here, but I do think that you can't argue from
>finding yourself at a particular point on your world-line to that
>world-line having finite length, because you are guaranteed to find
>yourself at that particular point at some (ah) point.
Right, which is why I'm (now) careful not to make *that* argument by
arbritarily using one's current age to base a reference point on. (e.g. in
my reply to Bruno.) Rather, I argue that from being at a point prior to
some _natural reference point_ such as the "can calculate my age" crierion,
one can conclude that one's world-line is finite.
>So I'm rejecting, not Bayesian logic per se, but the application of it to
>what (according to QTI) would be a very special (but still allowable) case.
There are no grounds to reject it in this case, since it would be
reliable almost all of the time. There's no difference between using a
method because it works for most people vs. using a method because it works
for me most of the time. At any given time, it works for most people, too.
>The basic problem is that we experience observer moments as a sequence.
>Hence we *must* experience the earlier moments before the later ones, and
>if we happen to come across QTI before we reach "QTI-like" observer moments
>then we might reject it for lack of (subjective) evidence. But that doesn't
>contradict QTI, which predicts that we have to pass through these earlier
>moments, and that we will observe everyone else doing so as well.
>I wish I could put that more clearly, or think of a decent analogy, but do
>you see what I mean? Our observations aren't actually *incompatible* with
>QTI, even if they do only cover an infinitsimal chunk of our total observer
>moments.
Indeed so, I know only too well what you mean. This has come up more
than once on the list.
I hope you understand why I say it's irrelevant. _Just like_ in the A/B
case, it would be wrong to not use Bayesian reasoning just because seeing A
is, yes, compatible with both #1 and #2. Seeing A could even have been a
way to confirm theory #2, if the rival theory #1 hadn't existed. The bottom
line is that Bayesian reasoning usually works for most people.
- - - - - - -
Jacques Mallah (jackmallah.domain.name.hidden)
Physicist / Many Worlder / Devil's Advocate
"I know what no one else knows" - 'Runaway Train', Soul Asylum
My URL:
http://hammer.prohosting.com/~mathmind/
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Received on Mon Sep 03 2001 - 18:13:39 PDT