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5515
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Imaginary cases are good for revealing our beliefs, rather than the truth [Parfit]
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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.
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From:
Derek Parfit (The Unimportance of Identity [1995], p.293)
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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.
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11023
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The logical connectives are 'defined' by their introduction rules [Gentzen]
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Full Idea:
The introduction rules represent, as it were, the 'definitions' of the symbols concerned, and the elimination rules are no more, in the final analysis, than the consequences of these definitions.
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From:
Gerhard Gentzen (works [1938]), quoted by Stephen Read - Thinking About Logic Ch.8
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A reaction:
If an introduction-rule (or a truth table) were taken as fixed and beyond dispute, then it would have the status of a definition, since there would be nothing else to appeal to. So is there anything else to appeal to here?
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11213
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Each logical symbol has an 'introduction' rule to define it, and hence an 'elimination' rule [Gentzen]
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Full Idea:
To every logical symbol there belongs precisely one inference figure which 'introduces' the symbol ..and one which 'eliminates' it. The introductions represent the 'definitions' of the symbols concerned, and eliminations are consequences of these.
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From:
Gerhard Gentzen (works [1938], II.5.13), quoted by Ian Rumfitt - "Yes" and "No" III
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A reaction:
[1935 paper] This passage is famous, in laying down the basics of natural deduction systems of logic (ones using only rules, and avoiding axioms). Rumfitt questions whether Gentzen's account gives the sense of the connectives.
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5516
|
Reduction can be by identity, or constitution, or elimination [Parfit, by PG]
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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.').
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From:
report of Derek Parfit (The Unimportance of Identity [1995], p.295) by PG - Db (ideas)
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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.
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5514
|
Psychologists are interested in identity as a type of person, but philosophers study numerical identity [Parfit]
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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.
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From:
Derek Parfit (The Unimportance of Identity [1995], p.293)
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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.
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5521
|
If my brain-halves are transplanted into two bodies, I have continuity, and don't need identity [Parfit]
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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.
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From:
Derek Parfit (The Unimportance of Identity [1995], p.314)
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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.
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1392
|
If we split like amoeba, we would be two people, neither of them being us [Parfit]
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Full Idea:
In the case of the man who, like an amoeba, divides….we can suggest that he survives as two different people without implying that he is those people.
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From:
Derek Parfit (Personal Identity [1971], §1)
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A reaction:
Maybe an amoeba is a homogeneous substance for which splitting is insignificant, but when a person has certain parts that are totally crucial, splitting them is catastrophic, and quite different. I'm not sure that splitting a self would leave persons.
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5519
|
It is fine to save two dying twins by merging parts of their bodies into one, and identity is irrelevant [Parfit]
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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.
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From:
Derek Parfit (The Unimportance of Identity [1995], p.308)
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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?
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5520
|
If two humans are merged surgically, the new identity is a purely verbal problem [Parfit]
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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.
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From:
Derek Parfit (The Unimportance of Identity [1995], p.310)
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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.
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1391
|
Concern for our own lives isn't the source of belief in identity, it is the result of it [Parfit]
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Full Idea:
Egoism, and the fear not of near but of distant death, and the regret that so much of one's life should have gone by - these are not, I think, wholly natural or instinctive. They are strengthened by a false belief in stable identity.
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From:
Derek Parfit (Personal Identity [1971], §6)
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A reaction:
This raises some very nice questions, about the extent to which various aspects of self-concern are instinctive and natural, or culturally induced, and even totally misguided and false. I can worry about the distant death of my guinea pig, or my grandson.
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9762
|
We should focus less on subjects of experience, and more on the experiences themselves [Parfit]
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Full Idea:
It becomes more plausible, when thinking morally, to focus less upon the person, the subject of experiences, and instead to focus more upon the experiences themselves.
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From:
Derek Parfit (Reasons and Persons [1984], §116)
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A reaction:
This pinpoints how Parfit moves from a view of persons in terms of continuity of consciousness to a utilitarian morality. It brings out nicely what is wrong with utilitarianism - the reductio of a great ball of nice experiences, with no one having them.
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