> -----Original Message-----
> From: Jacques Mallah [mailto:[EMAIL PROTECTED]]
>
> >From: "Charles Goodwin" <[EMAIL PROTECTED]>
> >Hi, I have just joined this list after seeing it mentioned
> on the Fabric of
> >Reality list....
>
>     Hi.  BTW, what's up on the FOR list?  Ever see anything interesting
> there?  I thought the book sucked except for chapter 2 (I think; the one
> explaining the MWI), but at least there are some MWIers on
> that list I would think.

I find it interesting. I don't necessarily believe the MWI myself but it is the main 
topic of conversation. Presently the main
thread seems to be concerned with the computational theory of reality.

> >I must ask, though, what makes you think that a typical
> observer ISN'T much
> >older than the lifetime of his species would allow?
>
>     I'm not so old, but if FIN were true, the effective
> chance of me being
> old would be 100%.  So by Bayesian reasoning, it must be false.

Hm, but there is a selection principle involved - you have to live through the first 
100, the first million years, etc. If you
haven't yet done so then you can't apply any sort of statistical argument to your own 
experience unless you assume that you're a
typical observer. But if you do that you're just assuming the result you want. My 
argument is that for all we know there may be far
more typical observers with ages between say 100 and the origin of the human race in 
existence, but the chances of any of them
existing in our branch of the multiverse is "thermodynamically low" - i.e. probably 
less than 1 in a googol or so. Since (1) you
can't observe a typical observer who isn't yourself (according to the QTI) and (2) you 
are in a special state yourself, of not
having yet reached the age where you start to suspect the QTI is correct, it's 
impossible for you to make any reasonable assumptions
about the QTI (i.e. whether it's true or false). Like the MWI, the QTI can only be 
deduced fairly indirectly.

My objections to the QTI are more along the lines of how the mechanism is supposed to 
work - why can't you experience your own
death, or just stop having experiences altogether, in 99.99999(etc)% of the universes 
that contain you?

>     On the contrary, you do use a SSA.  After all, you will
> never (for any
> question) have more than the one data point for use in the
> SSA.  But with a
> probability of 0% or 100%, that's plenty!

The problem is that the probability isn't 0% that you'd find yourself at your current 
age (according to the QTI - assume I put that
after every sentence!). Because you HAVE to pass through your current age to reach 
QTI-type ages, the probability of finding
yourself at your current age at some point is 100%. Using your argument (assuming 
QTI...) then your chances of finding yourself at
ANY age would be 0%. This imples to me that the SSA can't be used in this case, rather 
than that QTI *must* be wrong. After all
whether QTI is correct or not, you can imagine that it is and see what the results 
would be; and one result is that you will find
yourself (at some point) having any age from 0 to infinity, which is consistent with 
your current observations. In fact, the fact
that you are still alive is an argument for QTI (not a very strong one, though!)

> > >     It means - and I admit it does take a little thought
> here - _I want
> >to follow a guessing procedure that, in general, maximizes
> the fraction of
> >those people (who use that procedure) who get the right
> guess_.  (Why would
> >I want a more error-prone method?)  So I use Bayesian
> reasoning with the
> >best prior available, the uniform one on observer-moments,
> which maximizes
> >the fraction of observer-moments who guess right.  No
> soul-hopping in that
> >reasoning, I assure you.

That's OK so far. And it turns out correctly for most cases (i.e. 99.99999999(etc)% of 
observers WILL turn out to have ages of
infinity (if QTI etc)). But an infinitesimal fraction won't - including everyone you 
observe around you (the multiverse is very very
very (keep typing "very" til doomsday) big! (assuming MWI)).

> >
> >I'm sorry, I still don't see how that applies to me. If I know which
> >observer moments I'm in (e.g. I know how old I am) why should I
> >reason as though I don't?

(snip)

> In the same way, the SSA helps you guess things.  It's just a procedure to follow
> which usually helps the people that use it to make correct guesses.

It doesn't seem to help in this case though. I don't need to guess my age, it's a 
given. All I can deduce from it is that at some
point in my life I will experience this particular age. This deduction is compatible 
with the QTI. It is also compatible with
non-QTI (QTM, perhaps?)

Charles

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