On 18 July 2016 at 12:53, Bruce Kellett <bhkell...@optusnet.com.au> wrote:
> On 16/07/2016 5:05 pm, Bruno Marchal wrote: > > On 15 Jul 2016, at 04:00, Bruce Kellett wrote: > > On 15/07/2016 12:38 am, Bruno Marchal wrote: > > On 14 Jul 2016, at 02:11, Bruce Kellett wrote: > > > There is no single 1p view -- there are three possible 1p views in the > triplication scenario. > > > Right. The point is that from the first person perspective, those 1-views > are logically incompatible. > > > No they are not. They all refer to the experience of John Clark, as > defined by you. > > > Not at all. My definition, accepted by JKC, makes the M and the W-guy both > equal to the H-guy, but different between each other. In this context of > person, a =: b & a =: c does not entail that b =: c, with "=:" read as > "becomes". That is well known about modalities. > > > This is probably the heart of the matter. You are claiming that > transitivity does not obtain for personal identity: You say that the > person in Moscow is the same person as the person in Helsinki, and that the > person in Washington is also the same as the person in Helsinki. But also > claim that the person in Washington is not the same as the person in > Moscow, in contradiction with transitivity as applied to personal identity. > This might be true in modal logic, but the question remains as to whether > modal logic applies to personal identity. I suggest that it does not, and > that you have simply begged the question here. > > If personal identity is not transitive, then we have all sorts of problems > with the endurance of personal identity over time: if Bruce at age 30 > becomes Bruce at age 40, and Bruce at age 30 becomes Bruce at age 50, the > breakdown of transitivity would imply that Bruce at age 40 does not become > Bruce at age 50!!!!! > > The copy in Washington and the copy in Moscow, because they are distinct > physical objects, might well become different over time -- they have > different experiences, develop different likings, values, desires and so > forth over time, but this does not suffice to make them different persons, > else we would all become different persons over time. Poetically that might > be the case, but the problem of personal identity is to capture the > everyday experience and intuition that, despite all these changes wrought > by time, we remain the same single unique person over time. Consequently, > the differences that develop between the Washington and Moscow copies do > not suffice to make them different persons -- those same changes in the > individuals would, by the same token, make them both different from the > original person in Helsinki and we would not have duplication of persons at > all. > > The case of genetically identical twins might provide a possible insight > into the case of two persons having a single origin. Identical twins start > from a single fertilized egg that splits then, instead of that split > presaging further development of a single embryo, the two offshoot cells > develop separately to form two genetically identical embryos. In this case, > differences do arise between the twins, in embryo and post natal, and > although there has been a duplication in a real sense, we never get > confused into thinking that these two 'identical' twins are, in fact, just > one person. There is a breakdown of transitivity here if you trace back to > the original fertilized egg, but there is no confusion arising from the > thought that a 'person' has been duplicated. > The confusion arises due to first person psychological continuity. Take this out of the picture and what you are left with is unambiguous facts. > This is where the closest continuer theory shows its strength: you > maintain your unique identity through the changes and chances of time > because at any particular time, there is generally only one "continuer" > that could reasonably be supposed to be you. However, in the case of > duplication protocols, an element of ambiguity is introduced. The cleanest > way through this ambiguity is to suppose the if there is a tie for > 'closest' continuer (according to some metric for closeness), two new > persons are created, just as with the genetically identical twins -- the > split created two potential embryos, though both are identical to the > original egg, and these embryos develop into two distinct and different > people, without any confusion as to personal identity. > > So in your duplication scenarios, the case in which the original is > duplicated, but continues to exist, the closest continuer theory would have > some measure that gave significance to bodily continuity, so we would say > that the original person continued intact, and that, although sharing some > background with the continuer, a new individual was created in the > manufactured duplicate. In the duplication scenario in which the original > is cut or deleted, then there is no preferred unique continuer, so there is > a tie, and we would say that two new persons are created (the original > having been destroyed). > > If you think these things through, you can see that this theory of > personal identity resolves all the problems that your "psychological" > theory encounters. > Without a psychological theory of continuity this whole discussion would be unnecessary. We could just say that a person has been copied, the two copies are identical, and the original was destroyed. The problems arise because each copy has memories of being the original and, because of the phenomenon of first person experience, feels that he is the one true copy persisting through time - even though intellectually he knows this is not true. -- Stathis Papaioannou -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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