單元 24 哲學概論
人格同一 (2)
授課教師：王榮麟
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務合約及著作權法第46、52、65條合理使用
1
Accounts of Our Identity Through Time
(1) The psychological approach
 (2) The somatic approach

2
The Psychological Approach

Some psychological relation is necessary or
sufficient (or both) for one to persist. You are
that future being that in some sense inherits its
mental features—beliefs, memories, preferences,
the capacity for rational thought, that sort of
thing—from you; and you are that past being
whose mental features you have inherited in this
way.
3
The Psychological Approach
There is disagreement about what mental features
need to 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.

4
The Somatic Approach
Our identity through time consists in some
brute physical relation. You are 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.

5
The Somatic Approach


I am the same being as long as I have the same body—not
that the body must look the same as it 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。
6
A test case
Imagine that your brain is transplanted into my head. Two 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 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 nonpsychological, as the Somatic Approach has it.

7
心理派或身體派？










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？
8
Support for the psychological approach:
the brain-transplant case


Most people feel immediately drawn to the
Psychological Approach. 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
makes it easy to suppose that our identity over time has
something to do with psychology.
9
Still, the question remains…
It 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 in?

10
The Memory Criterion

Let’s 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.
11
Objections to the memory criterion

This proposal faces two objections, discovered
in the 18th century by Seargeant and Berkeley,
but more famously discussed by Reid and Butler.
12
The first objection
First, 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 paying 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.
Identity is transitive; memory continuity is not.

13
The 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 yourself 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 remember—that is, that memory continuity is sufficient for
personal identity.
It is uninformative because you cannot know whether someone genuinely
remembers a past experience without already knowing whether he is the one who
had it.

14
The second objection

Suppose 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 experience 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 is.
15
A more challenging problem


The Memory Criteria face a more obvious problem:
there are many times in my past that I can't 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
absurd 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.
16
Causal dependency to the rescue



A solution appeals to causal dependence (Shoemaker 1984, 89ff.).
We can define two notions, psychological connectedness and
psychological 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 connection—the experience causes the memory of
it—but there are others.
17
Psychologically continuous



Importantly, one's 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 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.
18
Psychologically continuous

Now 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.
19
Fission: a more serious worry for the Psychological
Approach
Whatever 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 cerebrum—the upper part of the brain largely responsible
for mental features—were transplanted, the recipient would be
psychologically continuous with you by anyone's 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。
21
Fission: a more serious worry for the
Psychological Approach
If we destroyed one of your cerebral hemispheres, the resulting being
would also be psychologically continuous with you.
(Hemispherectomy—even the removal of the left hemisphere, which
controls speech—is 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 transplanted
hemisphere would be psychologically continuous with you, and
according to the Psychological Approach would be you.

22
Fission: a more serious worry for the
Psychological Approach


But now suppose that both hemispheres are transplanted, each into a different
empty head. (We needn't pretend, as some authors do, that the hemispheres are
exactly alike.) The two recipients—call them Lefty and Righty—will 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, and one thing cannot be
numerically identical with two things. Suppose Lefty is hungry at a time when
Righty isn't. If you are Lefty, you are hungry at that time. If you are Righty, you
aren't. If you are Lefty and Righty, you are both hungry and not hungry at once: a
contradiction.
23
Two solutions to the fission problem

Friends of the Psychological Approach have
proposed two different solutions to this problem:
the “multiple-occupancy view” and the “nonbranching view”.
24
The multiple-occupancy view

The multiple-occupancy view says that 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.
25
The multiple-occupancy view



The 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 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.
26
The multiple-occupancy view
Lefty and Righty are like two roads that coincide 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
they themselves can't tell that they are two.
 Whether people really are made up of temporal parts, however, is
disputed.

27
The non-branching view

The other solution to the fission problem abandons the
intuitive claim that psychological continuity by itself
suffices for one to persist. It says, rather, that you are
identical with a past or future being only if she is then
psychologically continuous with you and no other being
is.
28

This 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 to exist—though
you would survive if only one were
transplanted and the other destroyed.
29
A surprising consequence of the non-branching
view
The 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 halves 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.

30
A surprising consequence of the non-branching
view



In 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 of psychological continuity,
you would cease to exist if your total brain state were copied
onto another brain without erasing your own brain.
31
A surprising consequence of the non-branching
view
Faced with the prospect of having one of your hemispheres transplanted,
there would seem to be no reason 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。

32
Parfit’s solution


Parfit, among others, tries to explain why we ought to
prefer death over our own continued existence:
Insofar as we are rational, we don't want to continue
existing. Or at least we don't want it for its own sake.
What I really want is for there to be someone in the
future who is psychologically continuous with me,
whether or not he is me.
33
Parfit’s solution
The 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 would result from her undergoing fission,
even if, as the non-branching view implies,
neither would be her.

34
Personal identity question has no practical
importance
In the fission case, the sorts of practical concerns you
ordinarily have for yourself seem to apply to someone who
isn't strictly you.
 This 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.

35
We may not persist by virtue of psychological
continuity


This may cast doubt on the principal argument for the
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.
36
We may not persist by virtue of psychological
continuity

Even if you would regard that person as yourself for all practical
purposes—if you would anticipate her experiences just as you anticipate
yours, for instance—that would in no way support the claim that she was
you. So our reactions to the brain-transplant case may not support the
view that we persist by virtue of psychological continuity, but only the
claim that psychological continuity is what matters practically, which is
compatible with other accounts of our persistence. In that case we may
wonder whether we have any reason to accept the Psychological
Approach.
37
Another Worry for the Psychological Approach

Imagine a three-dimensional duplicating machine. When you step into the “in” box,
it reads off your information and assembles a perfect duplicate of you in the “out”
box. The process causes temporary unconsciousness but is otherwise harmless. Two
beings wake up, one in each box. The boxes are indistinguishable. Because each
being will have the same apparent memories and perceive identical surroundings,
each will think that he or she is you, and will have the same evidence for this belief.
But only one will be right. If this actually happened to you, it is hard to see how you
could ever know, afterwards, whether you were the original or the duplicate.
(Suppose the technicians who work the machine are sworn to secrecy and immune to
bribes.) You would think, “Who am I? Am I who I think I am? Did I do the things I
seem to remember doing? Or did I come into being only a moment ago, complete
with false memories of someone else's life?” And you would have no way of
answering these questions.
38
問題

若non-branching view成立，則連續殺人
犯在被定罪之前只須趕快進行兩個半腦
同時移植手術，一旦成功便可逃避究責
問題。這樣合理嗎？
39
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本作品轉載自Microsoft Office 2003多媒體藝廊，依據Microsoft服務合約及著作權法第46、52、65
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1-46
2
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(1) The
psychological ......
somatic approach
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
3
Some
psychological ......
inherited in this
way.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
4
There is
disagreement ......
earlier is an
example.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
5
Our identity
through ......psych
ological facts.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
40
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Imagine that your
brain is ....Somatic
Approach has it
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Most people
feel ......do with
psychology.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
10
It is
notoriously ......ti
me consist in?
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
11
Let’s consider
the ...... or vice
versa.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
12
This proposal
faces ...... by Reid
and Butler.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
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First, suppose a
young ......transitiv
e; memory
continuity is not.
14
It seems to belong
to ......he is the
one who had it.
15
Suppose we want
to know ......is
supposed to tell
us whether she is.
16
The Memory
Criteria ...... night
was someone else.
17
A solution
appeals to
causal ......it—but
there are others.
版權標示
作者／來源
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
42
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18
Importantly, one's
current
mental ......connect
ions
19
Now suppose that
a ...... the
Memory Criterion.
20
Whatever
psychological ......
that she would be
you.
22
If we destroyed
one ......Approach
would be you.
23
But now suppose
that ......hungry at
once: a
contradiction.
版權標示
作者／來源
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
43
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24
Friends of the
Psychological ......
branching view”.
25
The multipleoccupancy ......me
rely separate
them.
26
The multipleoccupancy
view ......parts
afterwards.
27
Lefty and
Righty ......parts,
however, is
disputed.
28
The other
solution ...... no
other being is.
版權標示
作者／來源
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
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29
This means that
neither ......other
destroyed.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
30
The nonbranching ......be
your chance of
surviving.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
31
In fact
the ......erasing
your own brain.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
32
Faced with the
prospect
of ......continued
existence.
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Parfit, among
others......whether
or not he is me.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
45
版權聲明
頁碼
作品
34
The usual way to
achieve ......neither
would be her.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
In the fission case,
the ......continuou
s with whom.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
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This may cast
doubt ......would
not be you.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
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Even if ......the
Psychological
Approach.
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
38
Imagine a threedimensional ......a
nswering these
questions.
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作者／來源
Eric T. Olson，Stanford Encyclopedia of Philosophy，瀏覽日期：2014/05/05，
http://plato.stanford.edu/entries/identity-personal/，依據著作權法第46、52、65條合理使用。
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