On 10/9/2013 6:25 PM, chris peck wrote:
Hi Bruno
/>> I don't see why. There is a chance of 1/2 to feel oneself in M, and of 1/2 to feel
oneself in W, but the probability is 1 (assuming comp, the protocol, etc.) to find
oneself alive. /
This begs the question. And the probability of finding oneself alive is 1 in both your
view and mine.
/>> P(W v M) = P(W) + P(M) as W and M are disjoint incompatible (first person)
events. /
That they are disjoint is fine. And they are incompatible only insofar as no person,
Bruno-Helsinki, Bruno-Washington or Bruno-Moscow, in the experiment will experience both
simultaneously. But Bruno-Helsinki will experience each outcome.
Whats missing here is a discussion about what conditions are required in order to induce
a feeling of subjective uncertainty in Bruno-Helsinki. I think what is required is some
ignorance over the details of the situation, but there are none. Bruno-Helsinki knows
all there is to know about the situation that is relevant.
But one of the essential things about quantum mechanics is futures are uncertain even give
complete knowldge. If you use MWI then you expect that after observing a quantum random
outcome that there will be two (or more) copies of you that share the same memories up to
the observation, but are different after. So Bruno is just trying to show that the
uncertainty can be in "which copy is observing" instead of "which value was observed".
Whether this uncertainty can be represented as a probability is, I think, a problem in
both Bruno's thought experiment and in MWI of QM.
Brent
He knows that in his future there will be two 'copies' of him; one in Moscow, one in
Washington. By 'yes doctor' he knows that both these 'copies' are related to him in a
manner that preserves identity in exactly the same way. There will be no sense in which
Bruno-Washington is more Bruno-Helsinki than Bruno-Moscow. That is the essence of 'yes
doctor'. So, at the point in time when Bruno-Helsinki is asked what he expects to see,
there are no other relevant facts. Consequently there is no room for subjective uncertainty.
It would therefore be absurd of Bruno-Helsinki to assign a probability of 50% to either
outcome. It would be like saying only one of the future Bruno's shares a relationship of
identity with him. This is why I say your analysis violates the yes doctor axiom.
This can be contrasted with a response from either of the copies when asked the same
question. If asked before opening their eyes, both Bruno-Washington and Bruno-Moscow are
ignorant of their location. Ofcourse, apart from the fact that asking the question at
this point is far too late for Bruno-Helsinki, this is not a relevent fact for him.
Because he has no doubt that an identity maintaining version of him will be in each
location.
I have to admit, what with you being a professor and all that, I did begin to feel like
I was going mad. Luckily, the other day I found a paper by Hillary Greaves
"Understanding Deutcsh's Probability in a Deterministic Multiverse". Section 4.1
discusses subjective uncertainty in a generalized setting and argues for the exact same
conclusions I have been reaching just intuitively. This doesn't make either of us right
or wrong, but it gives me confidence to know that subjective uncertainty is not a
foregone conclusion as I sometimes have felt it has been presented on this list. It is
an analysis that has been peer reviewed and deemed worthy of publishing and warrants
more than the hand waving scoffs some academics here have been offering.
All the best
------------------------------------------------------------------------------------------
Date: Wed, 9 Oct 2013 15:36:12 -0700
From: meeke...@verizon.net
To: everything-list@googlegroups.com
Subject: Re: What gives philosophers a bad name?
On 10/9/2013 10:35 AM, John Clark wrote:
On Tue, Oct 8, 2013 at 1:19 PM, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
> How do you explain quantum mechanical probabilities in the Many Worlds
interpretation?
Not very well, assigning probabilities is unquestionably the weakest part
of the
Many Worlds theory. True, Everett derived the Born Rule from his ideas, but
not in a
way that feels entirely satisfactory, not that its competitors can do
better. The
Many Worlds interpretation is the best bad explanation of why Quantum
Mechanics works.
So you recognize that it has the same difficulties with probability and personal
identity as Bruno's teleportation.
Brent
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