On 10 October 2013 12:25, chris peck <[email protected]> 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. > > 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
When I toss a coin, I expect to see either heads or tails but not both, and in fact I see heads or tails but not both. In a multiverse, versions of me will see both heads and tails. Should I therefore conclude that I don't live in a multiverse? -- Stathis Papaioannou -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.
