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Personal Identity General problems and questions of personal identity: What is it to be a person?
What is it to be me, rather than anybody else?
What evidence can we use to know that a person seen today is the same person as we see tomorrow?
The chief issue - what is necessary and sufficient for a past or future being to be you?
Distinction between 'psychological connectedness' and 'psychological continuity': two individuals across time are psychologically connected if there exist some direct relation between them - if A remembers most of B's life, A and B are psychologically connected. However if A remembers most of B's life, and B remembers most of C's, A and C are not psychologically connected, since psychological connectedness is non-transitive, but they are psychologically continuous, since psychological continuity only requires overlapping chains of direct psychological connections, and is thus transitive. Parfit - Personal Identity Parfit targets two beliefs:
1. that questions about personal identity must have a definitive answer - Parfit suggests that it is possible to describe cases for which our criteria of personal identity are, at present, insufficient, and that since some of these are possible, they would present a problem given our current criteria.
2. that personal identity is of critical importance: whatever happens between now and any future time, either I will exist, or I will not - any future experience is mine, or it is not. Subsequently, if we cannot answer the question of personal identity, we cannot answer further important questions, regarding responsibility or survival. Parfit intends to claim against 2. that whilst certain other important questions do presuppose a question about personal identity, they can be relieved of this presupposition, and thus the question of personal identity is not so important as we originally imagined. The fission case Suppose my brain is divided and housed, half each, in two new bodies. Both resulting people have my character, and apparent memories of my life. Three options:
3. I do not survive. I survive as one, but not the other, of the two resulting people. I survive as both.
Problem with 1: if we have agreed that I could survive my brain being transplanted, and we can agree that people have survived with half their brains destroyed or damaged, it seems to follow that I could survive having my brain transplanted, and half of it destroyed. If this is so, how could I not survive if the other half, rather than being destroyed, were simply also transplanted? 'How could a double success be a failure?' Problem with 2: Clearly the two resulting people have equal claim to be me, since they each have half my brain. What can make me one of them rather than the other?
This seems to leave 3 as our only option. Can I survive as both? If 'survive' implies continued identity, then this makes no sense, since one person cannot be identical to two. However, it does not even need to be hypothetical to show that the 'two resulting people' are in fact one person, with a divided mind - cutting the bridge between the hemispheres of the brain results in two 'separate spheres of consciousness', controlling separate halves of the body, but both being experienced by the patient. Admittedly this has not been done across two bodies, though... Parfit's exam example: imagine I am able to voluntarily disconnect and reconnect the two
hemispheres of my brain - I might decide to divide my brain toward the end of an exam, to allow me to better focus on two separate questions at once. A person's mental history need not be a single flow, but might have separate streams that diverge and rejoin. It does not appear absolutely absurd, then, to think that option 3 (above) is possible, but still, it is unsatisfactory. We must concede in 3 that the two resulting people are different people, undoubtedly. Can we claim that I survive as both, using 'survive' to imply identity? We could suggest that two people can comprise a third, thus neither of those people alone is me, but I survive in them together. This idea, however, only retains the language of identity by changing the concept of a person. Parfit instead suggests that we drop the language of identity. Parfit wants to suggest that I survive as two different without implying that I am these people in the sense that we habitually mean it: who I am and who I survive as can be different. Parfit intends to make us think about questions of personal identity in the same way as we do about national identity, for example - in such a way that it does not matter that there is no true answer to questions about identity. The fission case shows that it is impossible for their to be true answers to all questions of identity, but also undermines the notion that important questions hinge upon the nature of personal identity. Parfit argues that the problem with our current understanding of identity is that we demand very specific answers to the question of identity, all of which seem highly implausible. But Parfit argues that this is only a problem if we maintain those two beliefs he began with:
1. that questions of personal identity can be answered definitively, and
2. that questions of critical importance hinge upon the answer to the question of personal identity. Parfit thus answers the first by reference the fission case and the three possible results - these show that our current language of identity cannot deal with all possible situations relating to the question of identity. He answers the second by asserting that we should prize apart these questions that are of importance - of personal responsibility, for example - from the question of identity, such that the question of identity may remain unsolved in any definitive sense, but becomes irrelevant to those important questions now distinct from it. The most important element that Parfit believes should be detached from 'identity' is 'survival'. Survival Survival does seem to presuppose identity as equivalent to it, however we can show that they are not quite equivalent: it has been argued in option 3 above I am no longer either of the resulting people, but this seems to suggest that my relation to each of the resulting people is such that it does not contain whatever element is necessary for personal survival. However we already agreed that the same relation between myself and the one resulting person that my entire brain is transplanted into does contain whatever is necessary for survival, so here it is only the act of duplication that removes this survival element. Parfit concludes here that the relation of the original person to the resulting person or people is all that matters in cases of survival - as such whilst identity is a one-one relation, survival need not be!
Parfit asserts that the belief that identity is what matters, or essentially that survival is equivalent to identity, is difficult to overcome. The fission case drives the first wedge between these two concepts, are otherwise run concurrently in all other aspects of our lives. Parfit attempts to show that what matters to the continued existence of a person is 'relations of degree'. The distinction between successive selves is made by reference to degrees of psychological connectedness, of which the term 'I' is the greatest. It is in fact surprisingly natural to suggest that if there
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