人格同一2000001

1、(2) 單元 24 哲學概論授課教師：王榮麟【本著作除另有註明外，採取創用CC姓名標示非商業性相同方式分享台灣3.0版授權釋出】1Accounts of Our Identity Through Time(1) The psychological approach(2) The somatic approach2The Psychological ApproachSome psychological relation is necessary or sufficient (or both) for one to persist. You are that future being that i

2、n some sense inherits its mental featuresbeliefs, memories, preferences, the capacity for rational thought, that sort of thingfrom you; and you are that past being whose mental features you have inherited in this way.3The Psychological ApproachThere is disagreement about what mental features need to

3、 be inherited.But most philosophers writing on personal identity since the early 20th century have endorsed some version of the Psychological Approach. The Memory Criterion mentioned earlier is an example.4The Somatic ApproachOur identity through time consists in some brute physical relation. You ar

4、e that past or future being that has your body, or that is the same biological organism as you are, or the like. Whether you survive or perish has nothing to do with psychological facts.5The Somatic ApproachI am the same being as long as I have the same bodynot that the body must look the same as it

5、 did years ago, but that there is a body, which I was born with and which exists continuously as long as I live. There was not a moment during all that time in which this body did not exist.不管我的外表、習慣、性情如何改變，只要我與生俱來的身體持續存在，我還是原來的我。6A test caseImagine that your brain is transplanted into my head. Two

6、beings result: the person who ends up with your cerebrum and most of your mental features, and the empty-headed being left behind, which may perhaps be biologically alive but will have no mental features. Those who say that you would be the one who gets your brain usually say so because they believe

7、 that some relation involving psychology suffices for you to persist: they accept the Psychological Approach. Those who say that you would be the empty-headed vegetable say so because they take your identity to consist in something entirely non-psychological, as the Somatic Approach has it.7心理派或身體派？

8、殺死情婦後的名醫還是原來的名醫嗎？歷經學識英博之改變後的呂蒙還是昔日吳下阿蒙嗎？失憶後的人還是原來的他嗎？人格驟變後的人還是原來的他嗎？植物人還是原來的他嗎？你是當初在你媽媽子宮裡的那個受精卵嗎？踏出傳輸機器後的人還是原來的他嗎？借屍還魂後的Mr. Jordan還是原來的他嗎？一早醒來身體遽變的人還是原來的他嗎？被醫生救回來的人是辛先生或是申先生？8Support for the psychological approach: the brain-transplant case Most people feel immediately drawn to the Psychological Ap

9、proach. It seems obvious that you would go along with your brain if it were transplanted, and that this is so because that organ would carry with it your memories and other mental features. This would lead the recipient to believe that he or she was you. And why should this belief be mistaken? This

10、makes it easy to suppose that our identity over time has something to do with psychology.9Still, the question remainsIt is notoriously difficult, however, to get from this conviction to a plausible answer to the Persistence Question:What psychological relation might our identity through time consist

11、 in? 10The Memory CriterionLets consider the memory criterion: a past or future being might be you if and only if you can now remember an experience she had then, or vice versa.11Objections to the memory criterionThis proposal faces two objections, discovered in the 18th century by Seargeant and Ber

12、keley, but more famously discussed by Reid and Butler.12The first objectionFirst, suppose a young student is fined for overdue library books. Later, as a middle-aged lawyer, she remembers paying the fine. Later still, in her dotage, she remembers her law career, but has entirely forgotten not only p

13、aying the fine but everything else she did in her youth. According to the Memory Criterion the young student is the middle-aged lawyer, the lawyer is the old woman, but the old woman is not the young student. This is an impossible result: if x and y are one and y and z are one, x and z cannot be two

14、. Identity is transitive; memory continuity is not.13The second objection你即為其經驗可被你記起的人，這種說法是trivial and uninformative。理由如下：It seems to belong to the very idea of remembering that you can remember only your own experiences. To remember paying a fine (or the experience of paying) is to remember yourse

15、lf paying. （我所記得的經驗就只能是我自己的經驗，我不可能回想起他人曾經歷過的經驗）That makes it trivial and uninformative to say that you are the person whose experiences you can rememberthat is, that memory continuity is sufficient for personal identity.It is uninformative because you cannot know whether someone genuinely remembers

16、a past experience without already knowing whether he is the one who had it.14The second objectionSuppose we want to know whether 今先生, who exists now, is the same as 古先生, whom we know to have existed at some time in the past. The Memory Criterion tells us that 今先生 is 古先生 if 今先生 can now remember an ex

17、perience of 古先生 that occurred at that past time. But 今先生s seeming to remember one of 古先生s experiences from that time counts as genuine memory only if 今先生 actually is 古先生. So we should already have to know whether 今先生 is 古先生 before we could apply the principle that is supposed to tell us whether she

18、is.15A more challenging problemThe Memory Criteria face a more obvious problem: there are many times in my past that I cant remember at all. For instance, there is no time when I could recall anything that happened to me while I was dreamlessly sleeping last night. The Memory Criterion has the absur

19、d implication that I have never existed at any time when I was completely unconscious. The man sleeping in my bed last night was someone else.16Causal dependency to the rescueA solution appeals to causal dependence (Shoemaker 1984, 89ff.). We can define two notions, psychological connectedness and p

20、sychological continuity. A being is psychologically connected, at some future time, with me as I am now just if he is in the psychological states he is in then in large part because of the psychological states I am in now. Having a current memory of an earlier experience is one sort of psychological

21、 connectionthe experience causes the memory of itbut there are others.17Psychologically continuousImportantly, ones current mental states can be caused in part by mental states one was in at times when one was unconscious. For example, most of my current beliefs are the same ones I had while I slept

22、 last night: those beliefs have caused themselves to continue existing. We can then define the second notion thus: I am now psychologically continuous with a past or future being just if some of my current mental states relate to those he is in then by a chain of psychological connections.18Psycholo

23、gically continuousNow suppose that a person x who exists at one time is identical with something y existing at another time if and only if x is, at the one time, psychologically continuous with y as it is at the other time. This avoids the most obvious objections to the Memory Criterion.19Fission: a

24、 more serious worry for the Psychological ApproachWhatever psychological continuity may amount to, a more serious worry for the Psychological Approach is that you could be psychologically continuous with two past or future people at once. If your cerebrumthe upper part of the brain largely responsib

25、le for mental featureswere transplanted, the recipient would be psychologically continuous with you by anyones lights (even if there would also be important psychological differences). The Psychological Approach implies that she would be you.20半腦切除術案例有位小女孩患有慢性局部腦炎（Rasmussen Syndrome）。癲癇導致她右半身癱瘓，並且嚴重

26、影響其語言技能。於是醫生在她三歲時施行了半腦切除術。當她七歲時，小女孩仍然能夠流利地說雙語（土耳其語和荷蘭語）。甚至半身癱瘓的狀況也已部份復原，只有左手和左腳有輕微痙攣現象。除此之外，她與正常人生活幾乎無異。 21Fission: a more serious worry for the Psychological ApproachIf we destroyed one of your cerebral hemispheres, the resulting being would also be psychologically continuous with you. (Hemispherec

27、tomyeven the removal of the left hemisphere, which controls speechis considered a drastic but acceptable treatment for otherwise-inoperable brain tumors: see Rigterink 1980.) What if we did both at once, destroying one hemisphere and transplanting the other? Then too, the one who got the transplante

28、d hemisphere would be psychologically continuous with you, and according to the Psychological Approach would be you.22But now suppose that both hemispheres are transplanted, each into a different empty head. (We neednt pretend, as some authors do, that the hemispheres are exactly alike.) The two rec

29、ipientscall them Lefty and Rightywill each be psychologically continuous with you. The Psychological Approach implies that any future being who is psychologically continuous with you must be you. It follows that you are Lefty and also that you are Righty. But that cannot be: Lefty and Righty are two

30、, and one thing cannot be numerically identical with two things. Suppose Lefty is hungry at a time when Righty isnt. If you are Lefty, you are hungry at that time. If you are Righty, you arent. If you are Lefty and Righty, you are both hungry and not hungry at once: a contradiction.Fission: a more s

31、erious worry for the Psychological Approach23Two solutions to the fission problemFriends of the Psychological Approach have proposed two different solutions to this problem: the “multiple-occupancy view” and the “non-branching view”. 24The multiple-occupancy viewThe multiple-occupancy view says that

32、 if there is fission in your future, then there are two of you, so to speak, even now. What we think of as you is really two people, who are now exactly similar and located in the same place, doing the same things and thinking the same thoughts. The surgeons merely separate them.25The multiple-occup

33、ancy viewThe multiple-occupancy view is almost invariably combined with the general metaphysical claim that people and other persisting things are made up of temporal parts. For each person, there is such a thing as her first half: an entity just like the person only briefer, like the first half of

34、a race. On this account, the multiple-occupancy view is that Lefty and Righty coincide before the operation by sharing their pre-operative temporal parts, and diverge later by having different temporal parts located afterwards.26The multiple-occupancy viewLefty and Righty are like two roads that coi

35、ncide for a stretch and then fork, sharing some of their spatial parts but not others. At the places where the roads overlap, they are just like one road.Likewise, the idea goes, at the times before the operation when Lefty and Righty share their temporal parts, they are just like one person. Even t

36、hey themselves cant tell that they are two.Whether people really are made up of temporal parts, however, is disputed.27The non-branching viewThe other solution to the fission problem abandons the intuitive claim that psychological continuity by itself suffices for one to persist. It says, rather, th

37、at you are identical with a past or future being only if she is then psychologically continuous with you and no other being is.28This means that neither Lefty nor Righty is you. They both come into existence when your cerebrum is divided. If both your cerebral hemispheres are transplanted, you cease

38、 to existthough you would survive if only one were transplanted and the other destroyed.29A surprising consequence of the non-branching viewThe non-branching view has the surprising consequence that if your brain is divided, you will survive if only one half is preserved, but you will die if both ha

39、lves are. Fission is death. That is just the opposite of what most of us expect: if your survival depends on the functioning of your brain (because that is what underlies psychological continuity), then the more of that organ we preserve, the greater ought to be your chance of surviving.30A surprisi

40、ng consequence of the non-branching viewIn fact the non-branching view implies that you would perish if one of your hemispheres were transplanted and the other left in place: you can survive hemispherectomy only if the excised hemisphere is immediately destroyed.And if brain-state transfer is a case

41、 of psychological continuity, you would cease to exist if your total brain state were copied onto another brain without erasing your own brain.31A surprising consequence of the non-branching viewFaced with the prospect of having one of your hemispheres transplanted, there would seem to be no reason

42、to prefer that the other be destroyed. Most of us would rather have both preserved, even if they go into different heads. Yet on the non-branching view that is to prefer death over continued existence.如果是進行手術的人是你，你會不會關心手術後那兩個人的前途、福禍與榮辱，如同你關心你自己未來的前途、福禍與榮辱一樣？若是會，你為什麼會呢？既然那兩個人都已不再是你。若是不會，這未免也太怪異了。 32P

43、arfits solutionParfit, among others, tries to explain why we ought to prefer death over our own continued existence:Insofar as we are rational, we dont want to continue existing. Or at least we dont want it for its own sake. What I really want is for there to be someone in the future who is psycholo

44、gically continuous with me, whether or not he is me. 33Parfits solutionThe usual way to achieve this is to continue existing; but the fission story shows that I could have it without continuing to exist. Likewise, even the most selfish person has a reason to care about the welfare of the beings who

45、would result from her undergoing fission, even if, as the non-branching view implies, neither would be her.34Personal identity question has no practical importanceIn the fission case, the sorts of practical concerns you ordinarily have for yourself seem to apply to someone who isnt strictly you. Thi

46、s suggests more generally that facts about who is numerically identical with whom have no practical importance. All that matters practically is who is psychologically continuous with whom.35We may not persist by virtue of psychological continuityThis may cast doubt on the principal argument for the

47、Psychological Approach. Suppose you would care about the welfare of your two fission offshoots in just the way that you ordinarily care about your own welfare, even though neither offshoot would be you. Then you would care about what happened to the person who got your whole brain in the original transplant case, even if she would not be you.36We may not persist by virtue of psychological continuityEven if you would regard that person as yourself for all practical purposesif you would anticipate her experiences just as you anticipate