Ideas from 'The Unimportance of Identity' by Derek Parfit [1995], by Theme Structure

[found in 'Personal Identity' (ed/tr Martin,R /Barresi,J) [Blackwells 2003,0-0631-23442-x]].

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2. Reason / E. Argument / 7. Thought Experiments
Imaginary cases are good for revealing our beliefs, rather than the truth
                        Full Idea: I believe it is worth considering imaginary cases (such as Teletransportation), as we can use them to discover, not what the truth is, but what we believe.
                        From: Derek Parfit (The Unimportance of Identity [1995], p.293)
                        A reaction: The trouble is that we might say that IF I were suddenly turned into a pig, then I would come to believe in dualism, but that will not and cannot happen, because dualism is false. It seems essential to accept the natural possibility of the case.
7. Existence / C. Structure of Existence / 2. Reduction
Reduction can be by identity, or constitution, or elimination
                        Full Idea: We can distinguish Identifying Reductionism (as in 'persons are bodies'), or Constitutive Reductionism (as in 'persons are distinct, but consist of thoughts etc.'), or Eliminative Reductionism (as in 'there are no persons, only thoughts etc.').
                        From: report of Derek Parfit (The Unimportance of Identity [1995], p.295) by PG - Db (ideas)
                        A reaction: Constitutive Reductionism seems the most common one, as in 'chemistry just consists of lots of complicated physics'. He doesn't mention bridge laws, which are presumably only required in more complicated cases of constitutive reduction.
16. Persons / D. Continuity of the Self / 1. Identity and the Self
Psychologists are interested in identity as a type of person, but philosophers study numerical identity
                        Full Idea: When psychologists discuss identity, they are typically concerned with the kind of person someone is, or wants to be (as in an 'identity crisis'). But when philosophers discuss identity, it is numerical identity they mean.
                        From: Derek Parfit (The Unimportance of Identity [1995], p.293)
                        A reaction: I think it is important to note that the philosophical problem breaks down into two areas: whether I have numerical identity with myself over time, and whether other people have it. It may be that two different sets of criteria will emerge.
16. Persons / D. Continuity of the Self / 2. Mental Continuity / b. Self as mental continuity
If my brain-halves are transplanted into two bodies, I have continuity, and don't need identity
                        Full Idea: If the two halves of my brain are transplanted into different bodies just like mine, they cannot both be me, since that would make them the same person. ..But my relation to these two contains everything that matters, so identity is not what matters.
                        From: Derek Parfit (The Unimportance of Identity [1995], p.314)
                        A reaction: I challenge his concept of what 'matters'. He has a rather solipsistic view of the problem, and I take Parfit to be a rather unsociable person, since his friends and partner will be keenly interested in the identities of the new beings.
Over a period of time what matters is not that 'I' persist, but that I have psychological continuity
                        Full Idea: We should revise our view about identity over time: what matters isn't that there will be someone alive who will be me; it is rather that there should be at least one living person who will be psychologically continuous with me as I am now.
                        From: Derek Parfit (The Unimportance of Identity [1995], p.316)
                        A reaction: Parfit and Locke seem to agree on this, and it is no accident that they both like 'science fiction' examples. Apparently Parfit wouldn't bat an eyelid if someone threatened to cut his corpus callosum. I rate it as a catastrophe for my current existence.
16. Persons / D. Continuity of the Self / 4. Split Consciousness
It is fine to save two dying twins by merging parts of their bodies into one, and identity is irrelevant
                        Full Idea: If I am largely paralysed, and my twin brother is dying of brain disease, then if the operation to graft my head onto his body is offered, I should accept the operation, and it is irrelevant whether this person would be me.
                        From: Derek Parfit (The Unimportance of Identity [1995], p.308)
                        A reaction: Parfit notes that the brain is a particularly significant part of the process. The fact that I might cheerfully accept this offer without philosophical worries doesn't get rid of the question 'who is this person?' Who should they remain married to?
If two humans are merged surgically, the new identity is a purely verbal problem
                        Full Idea: If there is someone with my head and my brother's body, it is a merely verbal question whether that person will be me, and that is why, even if it won't be me, that doesn't matter. ..What matters is not identity, but the facts of which identity consists.
                        From: Derek Parfit (The Unimportance of Identity [1995], p.310)
                        A reaction: It strikes me that from the subjective psychological point of view identity is of little interest, but from the objective external viewpoint (e.g. the forensic one) such questions are highly significant, and rightly so.
16. Persons / E. Rejecting the Self / 4. Denial of the Self
It doesn't matter whether I exist with half my components replaced (any more than an audio system)
                        Full Idea: It is quite uninteresting whether, with half its components replaced, I have the same audio system, and also whether I exist if half of my body were simultaneously replaced.
                        From: Derek Parfit (The Unimportance of Identity [1995], p.302)
                        A reaction: It is impossible to deny this, if the part replaced is not the brain. My doubt about Parfit's thesis is that while I may not care whether some modified thing is still me, my lawyers and the police might be very concerned.