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程序代写案例-PHI 001
时间：2022-06-08
PHI 001: Introduction to
Philosophy
2018
The Self and Identity Through Time
A Personal Identity Game
Staying Alive
http://www.philosophersnet.com/games/identity.htm
Identity: Numerical v. Qualitative
Qualitative Identity = Exact Similarity
Numerical Identity = Being One and the
Same Thing As
Identity: Numerical v. Qualitative
A B
Are A and B exactly similar?
Are A and B one and the same thing?
Identity: Numerical v. Qualitative
A B
Are A and B exactly similar?
Are A and B one and the same thing?
The Indiscernibility of Identicals
(Uncontroversial)
For any thing x and any thing y, if x is numerically
identical to y, then any property that x has y also
has, and any property that y has x also has –
i.e., then x and y have exactly the same
properties.
Contrapositive (Equivalent): If there is a property
that x has but y lacks, or a property that y has
but x lacks, then x is not numerically identical to
y.
Indiscernibility of Identicals
As a slogan: “Having exactly the same
properties is necessary for numerical
identity.”
Indiscernibility of Identicals
Obama has the property being over six feet
tall.
Gilmore does not have that property.
So Obama and Gilmore are not numerically
identical.
Identity of Indiscernibles
(Controversial)
For any thing x and any thing y, if x and y
have exactly the same properties, then x
and y are numerically identical.
Slogan: “Having exactly the same properties
is sufficient for numerical identity.”
Personal Identity
What is the question?
(Q1) How can we tell whether a person x,
existing at one time, is numerically the
same as some person y, existing at a
different time?
Personal Identity
What is the question?
(Q1) How can we tell whether a person x,
existing at one time, is numerically the
same as some person y, existing at a
different time?
No. This is epistemology.
Personal Identity
What is the question?
(Q2) What makes it the case that a person x
existing at one time is numerically identical with
a person y existing at a different time.
When doing metaphysics, we want a theory to
specify the grounds of personal identity over
time, not merely to give us a reliable to guide
that lets us find out when it holds.
Personal Identity
What do we want from a theory of personal identity over
time? In other words, what is the question that a theory
of personal identity over time is supposed to answer?
Necessarily, for any x and y, and times t and t*, if x is a
person and exists at t, and y exists at t*, then x = y if and
only if ___________________________.
We want a theory of personal identity to fill in the blank in a
way that makes the resulting statement both true and
informative. (To avoid circularity, what fills in the blank
must not presuppose an understanding of the concept of
personal identity over time.)
Personal Identity
The Matter Theory
• Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the
matter that x is made of at t is the same
matter as the matter that y is made of at
t*.
Is being made of the same matter really
sufficient for personal identity? Is it
really necessary?
The Matter Theory
Case 1: The anti-matter gun. Let Person1 be the
person who exists at t1 and is composed at t1 of
parcel of matter M. A split second after t1, the
anti-matter gun annihilates the matter that
composed the tip of Person1’s left pinky
fingernail. Let Person2 be the person who exists
(in roughly the same place as Person1 was
located at t1) shortly after the anti-matter gun is
applied. Person2 is composed at t2 of parcel of
matter M*. Parcel of matter M is not the same as
parcel of matter M* (they merely overlap).
The Matter Theory
Argument A against the matter theory
1. If the matter theory is true, then Person1
is not numerically identical to Person2.
2. Person1 is numerically identical to
Person2.
--------------------
3. The matter theory is not true.
The Matter Theory
Argument A, if successful, shows that
sameness of constituent matter is not
necessary ???
sufficient ???
for personal identity over time.
The Matter Theory
Argument A, if successful, shows that
sameness of constituent matter is not
necessary
for personal identity over time.
The Matter Theory
Case 2. Oratorious, the famed Roman statesman,
is composed at t1 of matter M. He dies, his
corpse rots, and M is scattered all over Earth.
Two thousand years later, by wild coincidence,
M has once again taken the form a person,
George U. Bush: Bush is composed of M at t2.
Aside from the odd fact that he is made of M,
there does not appear to be anything unusual
about his history: records indicate that he
developed from a 7 pound infant born in 1943.
The Matter Theory
Argument B against the matter theory
1. If the matter theory is true, then Oratorius
is numerically identical with George U.
Bush.
2. Oratorious is not numerically identical
with George U. Bush.
---------------------------
3. The matter theory is not true.
The Matter Theory
Argument B, if successful, shows that
sameness of constituent matter is not
necessary ???
sufficient ???
for personal identity over time.
The Matter Theory
Argument B, if successful, shows that
sameness of constituent matter is not
sufficient
for personal identity over time.
Personal Identity
The Soul Theory
• Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the soul
that x has at t is the same as the soul that
y has at t*.
Personal Identity
What is a soul? To count as a soul (as philosophers use the term), a
thing
• must be immaterial / non-physical / not made of matter,
• must be capable of causing things to happen, and be capable of
being causally affected by other things,
• must be conscious or play some essential role in giving rise to
consciousness, and
• must be a substance (a thing, like a rock or a ghost) rather than an
event (something that happens or occurs, like an explosion or a
basketball game) .
Personal Identity
The Soul Theory
• Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the soul
that x has at t is the same as the soul that
y has at t*.
Personal Identity
The Soul Theory
• Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the soul
that x has at t is the same as the soul that
y has at t*.
Is there any evidence for the existence of
souls?
The No Evidence Argument
1. If the soul theory is true, then either souls exist, or in
no case is a person existing at one time numerically
identical with some person existing at a different time.
2. In some cases a person existing at one time is
numerically identical with a person existing at a
different time.
3. There is no empirical evidence for souls.
4. If there is no empirical evidence for souls, then souls
do not exist.
----------------------
5. The soul theory is not true.
The No Evidence Argument
1. If the soul theory is true, then either souls exist, or in
no case is a person existing at one time numerically
identical with some person existing at a different time.
If A then (B or C)
2. In some cases a person existing at one time is
numerically identical with a person existing at a
different time. Not C
3. There is no scientific reason to postulate souls. D
4. If there is no scientific reason to postulate souls, then
souls do not exist. If D then not B
----------------------
5. The soul theory is not true. Not A
The Instantaneous View
Each of us exists, but we are all instantaneous and do not
persist through time. No one who exists at one instant, t, is
numerically identical to anyone who exists at a later instant,
t*.
There is a person who exists tomorrow who looks like you,
remembers much of what you remember, and answers to
your name, but that person is not you. You exist only now.
Arguments for Instantaneous View?
Argument against it?
The Body Theory
Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the
body that x has at t = the body that y has
at t*.
The Body Theory
Problem 1: Corpses
The Corpse Argument Against the Body Theory
1. The body of the corpse in my casket = my body.
2. If (1) and the Body Theory is true, then the corpse in my
casket is me.
3. The corpse in my casket is not me. (I’ll be gone then.)
---------------
4. The Body Theory is not true.
The Body Theory
Problem 2: Sydney Shoemaker’s Brown-
Brownson case.
Brown’s brain is transplanted into
Robinson’s body. The person who wakes
up, call him ‘Brownson’, answers to the
name ‘Brown’ and can describe Brown’s
life but shows no knowledge of Robinson’s
life.
The Body Theory
The ‘Brownson’ Argument
1. Brownson does not have Brown’s body.
2. If (1) and the Body theory are both true,
then Brownson is not Brown.
3. Brownson is Brown.
---------
: . The Body theory is not true.
The Brain Theory
Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the
brain that x has at t = the brain that y has
at t*.
The Brain Theory
Problem 1. Corpses and their brains
The Corpse Argument Against the Brain Theory
1. The brain of the corpse in the casket is my brain.
2. If (1) and the Brain Theory is true, then the corpse in
the casket is me.
3. The corpse in the casket is not me.
-------
.: The Brain theory is not true.
John Locke
1632—1704, English
A founding father of British Empiricism
Problem for Brain and Body theories: a version of
Locke’s “Prince and Cobbler” case
“Suppose the prince had previously committed a horrible
crime, knew the mind-swap would occur, and hoped to
use it to escape prosecution. After the swap, the crime is
discovered, and the guards come to take the guilty one
away. They know nothing of the swap, and so they haul
off to jail the person in the prince’s body, ignoring his
protestations of innocence. The person in the cobbler’s
body (who considers himself the prince) remembers
committing the crime and gloats over his narrow escape.
This is a miscarriage of justice! The gloating person in
the cobbler’s body ought to be punished. If so, then the
person in the cobbler’s body is the prince, not the
cobbler, for a person ought to be punished only for what
he himself did.” (Ted Sider, Riddles of Existence, pp. 14-
15)
The Memory Theory
Necessarily, if x is a person existing at t1
and y exists at a later time t2, x=y if and
only if y has memories at t2 of the
experiences that x had at t1.
The Memory Theory
Problem: The Brave Officer case.
Due to Thomas Reid (1710-1796, Scottish)
OldMan remembers fighting bravely on the
battlefield as an officer (BraveOfficer’s
experience).
BraveOfficer, while fighting bravely, remembers
stealing apples as a boy (Boy’s experience).
OldMan does not remember picking fruit.
The Memory Theory
Problem: The Brave Officer case.
Due to Thomas Reid (1710-1796, Scottish)
Assume that the Memory Theory is true
OldMan remembers fighting bravely on the battlefield as an officer
(BraveOfficer’s experience).
So: OldMan=Brave Officer (from Memory Theory)
BraveOfficer, while fighting bravely, remembers stealing apples as a
boy (Boy’s experience).
So: Brave Officer=Boy (from Memory Theory)
So: OldMan=Boy (from the transitivity of identity)
OldMan does not remember picking fruit.
So: Not-(OldMan=Boy) (from Memory Theory)
So: Oldman=Boy & Not-OldMan=Boy Contradiction
The Psychological Continuity
Theory
Necessarily, for any x and y and t1 and t2, if
x is a person and exists at t1 and y exists
at t2, then x=y if and only if there is a one-
way chain of memory connections linking x
at t1 and y at t2 – that is, if and only if x at
t1 is psychologically continuous with y
at t2.
The Psychological Continuity
Theory
Problem: Duplication
Suppose the two hemispheres of Tanya’s
brain (each of which encodes Tanya’s full
memory and personality) are transplanted
into two different brainless bodies. Each of
the resulting people, Righty and Lefty, is
psychologically continuous with Tanya
before the operation.
The Duplication Argument Against
PTC
1. If PCT is true, then Tanya = Righty and
Tanya = Lefty.
2. If Righty = Tanya and Tanya = Lefty,
then Righty = Lefty. (Identity is
transitive.)
3. Righty≠Lefty.
-----------------------
The PCT is not true.
The Non-Branching
Psychological Continuity Theory
Necessarily, if x is a person existing at t
and y exists at t, x=y if and only if x at t
and y at t* are related by ‘non-branching
psychological continuity’.
The Non-Branching Psychological
Continuity Theory
Problem: Extrinsicness
Suppose that I learn that I will undergo a fission operation tomorrow. According
to the Non-Branching theory, I survive if just one hemisphere ‘takes’, but I
don’t survive if neither takes, and I don’t survive if both take.
Righty, if he wakes up at all, will wake up in Room R, and Lefty, if he wakes up
at all, will wake up in Room L. According to the Non-Branching theory,
whether I wake up in Room R depends in part on what happens in Room L.
Assume all will go well in Room R. Then if all goes well in Room L, I won’t
wake up in Room R (or anywhere), but if the procedure in Room L fails,
then I do wake up in Room R. So whether I wake up in Room R depends
upon an ‘extrinsic fact’.
But whether some process supports my continued existence shouldn’t depend
upon extrinsic facts! It should depend only upon what that process is like
intrinsically.
The Non-Branching Psychological
Continuity Theory
A related odd feature of the Non-Branching
theory, as applied to the given case:
This theory tells us that in the given case,
‘double success’ is worse for me than
‘single success.’
The No-Self Theory
Roots in certain schools of ancient Indian Buddhism
• The Questions of Milinda (100s BC, record of conversation with
Nagasena), Milinda = Menander, Greek king of Bactria in today’s
Afghanistan
– The self is a conceptual construct, a designation, a convention, a
mere name
• Vasubandu (4th century AD): Reductionism? Eliminativism?
– ‘There is no self’, ‘There is no one called Caitra’.
• Nagarjuna (around 150 AD): rejects reduction of self, embraces
elimination of self.
• Santideva (early 8th century AD)
– ‘Without exception, no suffering belongs to anyone . . If one asks why suffering
should be prevented, no one disputes that! . . .If you argue: for whom is there
compassion if no being exists? [our response is] for anyone projected through the
illusion which is embraced for the sake of what has to be done.’
The No-Self Theory
The No-Self Theory: There are no people, souls, selves, or human
beings. Whenever the word ‘I’ is used, it fails to refer to anything.
Likewise for ‘you’, ‘she’, ‘he’, and ordinary proper names, such as
‘Obama’. These never refer to anything. You do not exist. Neither do I.
How could this be? Sorabji’s discussion of Buddhist views of the self
might help answer this question. Here’s a possibly related answer. . .
Compositional Nihilism: There are no composite entities, objects that
have parts. There are no chairs, tables, or people. There are simple,
fundamental particles (electrons, quarks, . . .). Some such particles are
arranged table-wise. Others are arranged human-wise. But there are
no groups or collections of particles, which would be composite
entities if they existed. There are just the particles themselves.
Composite objects are just ‘useful fictions’.
René Descartes (1596-
1650)
French philosopher and
mathematician
Inventor of analytic
geometry – ‘Cartesian
coordinates’
Corresponded with
Princess Elisabeth of
Bohemia (1618-1680)
The Cogito
The Cogito as an objection to the No-Self Theory.
Latin:
Cogito, ergo sum.
English:
I think, therefore I am.
or: I think, therefore I exist.
The Cogito
In the Meditations, Descartes never uses the
expression ‘cogito, ergo sum’/ ‘I think,
therefore I exist’.
In parts of other works (e.g., The Principles
of Philosophy), he does.
The Cogito
“This piece of knowledge – I think, therefore
I exist – is the first and most certain of all
to occur to anyone who philosophizes in
an orderly way.”
Principles of Philosophy, Part I section 7
The Cogito
I have just said that I have no senses and no body, and I am so
bound up with a body and with senses that one would think that I
can’t exist without them. Now that I have convinced myself that
there is nothing in the world—no sky, no earth, no minds, no
bodies—does it follow that I don’t exist either? No it does not
follow; for if I convinced myself of something then I certainly
existed.
Cogito v1
1. I am convinced that there is nothing in the world.
2. If I am convinced that there is nothing in the world, then I exist.
---------
: . I exist.
(adapted from Feldman 1986: 59)
The Cogito
But there is a supremely powerful and cunning deceiver who
deliberately deceives me all the time! Even then, if he is deceiving me I
undoubtedly exist: let him deceive me all he can, he will never bring it
about that I am nothing while I think I am something.
Cogito, v2
1. I am deceived by something.
2. If I am deceived by something, then I exist.
-----------
: . I exist.
Cogito, v3
1. I think that I am something.
2. If think that I am something, then I exist.
------------
: . I exist.
(Feldman 1986: 60)
The Cogito
Cogito, v4
1. I think.
2. Whatever thinks exists.
---------
: . I exist.
The Cogito
Cogito, v4
1. I think. (‘think’ means roughly ‘am conscious’ or ‘am
undergoing mental activity’)
[If you think that you are walking/talking/deceiving
someone/surprising someone/holding a diamond, you
might be mistaken. But if you think that you are thinking,
there is no chance that you are mistaken. Inferential interp:
So (1) can be a metaphysical certainty for Descartes.]
2. Whatever thinks exists.
---------
: . I exist.
The Cogito
Cogito, v4
1. I think. (‘think’ means roughly ‘am conscious’ or ‘am
undergoing mental activity’)
2. Whatever thinks exists.
[If a thing has any properties or features at all, it exists. If
won’t have properties at all if it’s not there to have them. If it
doesn’t exist, it can’t have any properties or features at all.
Thinking is a property. So whatever thinks must exist.
Inferential interp: so (2) was a metaphysical certainty for
Descartes.]
---------
: . I exist.
The Cogito
Lichtenberg’s objection
“We should say ‘it thinks’ just as we say ‘it lightens’
[or ‘it’s raining’]. To say cogito is already to say
too much as soon as we translate it ‘I think’. To
assume, to postulate the I is a practical
requirement.”
Georg Chistoph Lichtenberg, The Waste Books, K
18.
Georg Christoph Lichtenberg
1742-1799, German
The Cogito
Lichtenberg’s objection, as stated by
Bertrand Russell:
“I think” is [Descartes’s] ultimate premiss. Here the
word “I” is really illegitimate; he ought to state his
ultimate premiss in the form “there are thoughts”
(1945: 567).
The Cogito
A reply to Lichtenberg’s objection:
According to Russell, when the cogito is carried out, what is certain ‘from this
perspective’ is just following proposition:
R There are thoughts or experiences
But more is certain than R. If only R were certain, then it wouldn’t be certain that
the following is false:
I, Zombie There are other people, who are all conscious and
have thoughts and experiences, and I exist, but I’m not
conscious and don’t have any thoughts or experiences
at all.
But it is certain that I, Zombie is false. That can be ruled out, from ‘in here.’ So
something more than R must be certain.
Philosophy
2018
The Self and Identity Through Time
A Personal Identity Game
Staying Alive
http://www.philosophersnet.com/games/identity.htm
Identity: Numerical v. Qualitative
Qualitative Identity = Exact Similarity
Numerical Identity = Being One and the
Same Thing As
Identity: Numerical v. Qualitative
A B
Are A and B exactly similar?
Are A and B one and the same thing?
Identity: Numerical v. Qualitative
A B
Are A and B exactly similar?
Are A and B one and the same thing?
The Indiscernibility of Identicals
(Uncontroversial)
For any thing x and any thing y, if x is numerically
identical to y, then any property that x has y also
has, and any property that y has x also has –
i.e., then x and y have exactly the same
properties.
Contrapositive (Equivalent): If there is a property
that x has but y lacks, or a property that y has
but x lacks, then x is not numerically identical to
y.
Indiscernibility of Identicals
As a slogan: “Having exactly the same
properties is necessary for numerical
identity.”
Indiscernibility of Identicals
Obama has the property being over six feet
tall.
Gilmore does not have that property.
So Obama and Gilmore are not numerically
identical.
Identity of Indiscernibles
(Controversial)
For any thing x and any thing y, if x and y
have exactly the same properties, then x
and y are numerically identical.
Slogan: “Having exactly the same properties
is sufficient for numerical identity.”
Personal Identity
What is the question?
(Q1) How can we tell whether a person x,
existing at one time, is numerically the
same as some person y, existing at a
different time?
Personal Identity
What is the question?
(Q1) How can we tell whether a person x,
existing at one time, is numerically the
same as some person y, existing at a
different time?
No. This is epistemology.
Personal Identity
What is the question?
(Q2) What makes it the case that a person x
existing at one time is numerically identical with
a person y existing at a different time.
When doing metaphysics, we want a theory to
specify the grounds of personal identity over
time, not merely to give us a reliable to guide
that lets us find out when it holds.
Personal Identity
What do we want from a theory of personal identity over
time? In other words, what is the question that a theory
of personal identity over time is supposed to answer?
Necessarily, for any x and y, and times t and t*, if x is a
person and exists at t, and y exists at t*, then x = y if and
only if ___________________________.
We want a theory of personal identity to fill in the blank in a
way that makes the resulting statement both true and
informative. (To avoid circularity, what fills in the blank
must not presuppose an understanding of the concept of
personal identity over time.)
Personal Identity
The Matter Theory
• Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the
matter that x is made of at t is the same
matter as the matter that y is made of at
t*.
Is being made of the same matter really
sufficient for personal identity? Is it
really necessary?
The Matter Theory
Case 1: The anti-matter gun. Let Person1 be the
person who exists at t1 and is composed at t1 of
parcel of matter M. A split second after t1, the
anti-matter gun annihilates the matter that
composed the tip of Person1’s left pinky
fingernail. Let Person2 be the person who exists
(in roughly the same place as Person1 was
located at t1) shortly after the anti-matter gun is
applied. Person2 is composed at t2 of parcel of
matter M*. Parcel of matter M is not the same as
parcel of matter M* (they merely overlap).
The Matter Theory
Argument A against the matter theory
1. If the matter theory is true, then Person1
is not numerically identical to Person2.
2. Person1 is numerically identical to
Person2.
--------------------
3. The matter theory is not true.
The Matter Theory
Argument A, if successful, shows that
sameness of constituent matter is not
necessary ???
sufficient ???
for personal identity over time.
The Matter Theory
Argument A, if successful, shows that
sameness of constituent matter is not
necessary
for personal identity over time.
The Matter Theory
Case 2. Oratorious, the famed Roman statesman,
is composed at t1 of matter M. He dies, his
corpse rots, and M is scattered all over Earth.
Two thousand years later, by wild coincidence,
M has once again taken the form a person,
George U. Bush: Bush is composed of M at t2.
Aside from the odd fact that he is made of M,
there does not appear to be anything unusual
about his history: records indicate that he
developed from a 7 pound infant born in 1943.
The Matter Theory
Argument B against the matter theory
1. If the matter theory is true, then Oratorius
is numerically identical with George U.
Bush.
2. Oratorious is not numerically identical
with George U. Bush.
---------------------------
3. The matter theory is not true.
The Matter Theory
Argument B, if successful, shows that
sameness of constituent matter is not
necessary ???
sufficient ???
for personal identity over time.
The Matter Theory
Argument B, if successful, shows that
sameness of constituent matter is not
sufficient
for personal identity over time.
Personal Identity
The Soul Theory
• Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the soul
that x has at t is the same as the soul that
y has at t*.
Personal Identity
What is a soul? To count as a soul (as philosophers use the term), a
thing
• must be immaterial / non-physical / not made of matter,
• must be capable of causing things to happen, and be capable of
being causally affected by other things,
• must be conscious or play some essential role in giving rise to
consciousness, and
• must be a substance (a thing, like a rock or a ghost) rather than an
event (something that happens or occurs, like an explosion or a
basketball game) .
Personal Identity
The Soul Theory
• Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the soul
that x has at t is the same as the soul that
y has at t*.
Personal Identity
The Soul Theory
• Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the soul
that x has at t is the same as the soul that
y has at t*.
Is there any evidence for the existence of
souls?
The No Evidence Argument
1. If the soul theory is true, then either souls exist, or in
no case is a person existing at one time numerically
identical with some person existing at a different time.
2. In some cases a person existing at one time is
numerically identical with a person existing at a
different time.
3. There is no empirical evidence for souls.
4. If there is no empirical evidence for souls, then souls
do not exist.
----------------------
5. The soul theory is not true.
The No Evidence Argument
1. If the soul theory is true, then either souls exist, or in
no case is a person existing at one time numerically
identical with some person existing at a different time.
If A then (B or C)
2. In some cases a person existing at one time is
numerically identical with a person existing at a
different time. Not C
3. There is no scientific reason to postulate souls. D
4. If there is no scientific reason to postulate souls, then
souls do not exist. If D then not B
----------------------
5. The soul theory is not true. Not A
The Instantaneous View
Each of us exists, but we are all instantaneous and do not
persist through time. No one who exists at one instant, t, is
numerically identical to anyone who exists at a later instant,
t*.
There is a person who exists tomorrow who looks like you,
remembers much of what you remember, and answers to
your name, but that person is not you. You exist only now.
Arguments for Instantaneous View?
Argument against it?
The Body Theory
Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the
body that x has at t = the body that y has
at t*.
The Body Theory
Problem 1: Corpses
The Corpse Argument Against the Body Theory
1. The body of the corpse in my casket = my body.
2. If (1) and the Body Theory is true, then the corpse in my
casket is me.
3. The corpse in my casket is not me. (I’ll be gone then.)
---------------
4. The Body Theory is not true.
The Body Theory
Problem 2: Sydney Shoemaker’s Brown-
Brownson case.
Brown’s brain is transplanted into
Robinson’s body. The person who wakes
up, call him ‘Brownson’, answers to the
name ‘Brown’ and can describe Brown’s
life but shows no knowledge of Robinson’s
life.
The Body Theory
The ‘Brownson’ Argument
1. Brownson does not have Brown’s body.
2. If (1) and the Body theory are both true,
then Brownson is not Brown.
3. Brownson is Brown.
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: . The Body theory is not true.
The Brain Theory
Necessarily, if x is a person existing at t
and y exists at t*, x=y if and only if the
brain that x has at t = the brain that y has
at t*.
The Brain Theory
Problem 1. Corpses and their brains
The Corpse Argument Against the Brain Theory
1. The brain of the corpse in the casket is my brain.
2. If (1) and the Brain Theory is true, then the corpse in
the casket is me.
3. The corpse in the casket is not me.
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.: The Brain theory is not true.
John Locke
1632—1704, English
A founding father of British Empiricism
Problem for Brain and Body theories: a version of
Locke’s “Prince and Cobbler” case
“Suppose the prince had previously committed a horrible
crime, knew the mind-swap would occur, and hoped to
use it to escape prosecution. After the swap, the crime is
discovered, and the guards come to take the guilty one
away. They know nothing of the swap, and so they haul
off to jail the person in the prince’s body, ignoring his
protestations of innocence. The person in the cobbler’s
body (who considers himself the prince) remembers
committing the crime and gloats over his narrow escape.
This is a miscarriage of justice! The gloating person in
the cobbler’s body ought to be punished. If so, then the
person in the cobbler’s body is the prince, not the
cobbler, for a person ought to be punished only for what
he himself did.” (Ted Sider, Riddles of Existence, pp. 14-
15)
The Memory Theory
Necessarily, if x is a person existing at t1
and y exists at a later time t2, x=y if and
only if y has memories at t2 of the
experiences that x had at t1.
The Memory Theory
Problem: The Brave Officer case.
Due to Thomas Reid (1710-1796, Scottish)
OldMan remembers fighting bravely on the
battlefield as an officer (BraveOfficer’s
experience).
BraveOfficer, while fighting bravely, remembers
stealing apples as a boy (Boy’s experience).
OldMan does not remember picking fruit.
The Memory Theory
Problem: The Brave Officer case.
Due to Thomas Reid (1710-1796, Scottish)
Assume that the Memory Theory is true
OldMan remembers fighting bravely on the battlefield as an officer
(BraveOfficer’s experience).
So: OldMan=Brave Officer (from Memory Theory)
BraveOfficer, while fighting bravely, remembers stealing apples as a
boy (Boy’s experience).
So: Brave Officer=Boy (from Memory Theory)
So: OldMan=Boy (from the transitivity of identity)
OldMan does not remember picking fruit.
So: Not-(OldMan=Boy) (from Memory Theory)
So: Oldman=Boy & Not-OldMan=Boy Contradiction
The Psychological Continuity
Theory
Necessarily, for any x and y and t1 and t2, if
x is a person and exists at t1 and y exists
at t2, then x=y if and only if there is a one-
way chain of memory connections linking x
at t1 and y at t2 – that is, if and only if x at
t1 is psychologically continuous with y
at t2.
The Psychological Continuity
Theory
Problem: Duplication
Suppose the two hemispheres of Tanya’s
brain (each of which encodes Tanya’s full
memory and personality) are transplanted
into two different brainless bodies. Each of
the resulting people, Righty and Lefty, is
psychologically continuous with Tanya
before the operation.
The Duplication Argument Against
PTC
1. If PCT is true, then Tanya = Righty and
Tanya = Lefty.
2. If Righty = Tanya and Tanya = Lefty,
then Righty = Lefty. (Identity is
transitive.)
3. Righty≠Lefty.
-----------------------
The PCT is not true.
The Non-Branching
Psychological Continuity Theory
Necessarily, if x is a person existing at t
and y exists at t, x=y if and only if x at t
and y at t* are related by ‘non-branching
psychological continuity’.
The Non-Branching Psychological
Continuity Theory
Problem: Extrinsicness
Suppose that I learn that I will undergo a fission operation tomorrow. According
to the Non-Branching theory, I survive if just one hemisphere ‘takes’, but I
don’t survive if neither takes, and I don’t survive if both take.
Righty, if he wakes up at all, will wake up in Room R, and Lefty, if he wakes up
at all, will wake up in Room L. According to the Non-Branching theory,
whether I wake up in Room R depends in part on what happens in Room L.
Assume all will go well in Room R. Then if all goes well in Room L, I won’t
wake up in Room R (or anywhere), but if the procedure in Room L fails,
then I do wake up in Room R. So whether I wake up in Room R depends
upon an ‘extrinsic fact’.
But whether some process supports my continued existence shouldn’t depend
upon extrinsic facts! It should depend only upon what that process is like
intrinsically.
The Non-Branching Psychological
Continuity Theory
A related odd feature of the Non-Branching
theory, as applied to the given case:
This theory tells us that in the given case,
‘double success’ is worse for me than
‘single success.’
The No-Self Theory
Roots in certain schools of ancient Indian Buddhism
• The Questions of Milinda (100s BC, record of conversation with
Nagasena), Milinda = Menander, Greek king of Bactria in today’s
Afghanistan
– The self is a conceptual construct, a designation, a convention, a
mere name
• Vasubandu (4th century AD): Reductionism? Eliminativism?
– ‘There is no self’, ‘There is no one called Caitra’.
• Nagarjuna (around 150 AD): rejects reduction of self, embraces
elimination of self.
• Santideva (early 8th century AD)
– ‘Without exception, no suffering belongs to anyone . . If one asks why suffering
should be prevented, no one disputes that! . . .If you argue: for whom is there
compassion if no being exists? [our response is] for anyone projected through the
illusion which is embraced for the sake of what has to be done.’
The No-Self Theory
The No-Self Theory: There are no people, souls, selves, or human
beings. Whenever the word ‘I’ is used, it fails to refer to anything.
Likewise for ‘you’, ‘she’, ‘he’, and ordinary proper names, such as
‘Obama’. These never refer to anything. You do not exist. Neither do I.
How could this be? Sorabji’s discussion of Buddhist views of the self
might help answer this question. Here’s a possibly related answer. . .
Compositional Nihilism: There are no composite entities, objects that
have parts. There are no chairs, tables, or people. There are simple,
fundamental particles (electrons, quarks, . . .). Some such particles are
arranged table-wise. Others are arranged human-wise. But there are
no groups or collections of particles, which would be composite
entities if they existed. There are just the particles themselves.
Composite objects are just ‘useful fictions’.
René Descartes (1596-
1650)
French philosopher and
mathematician
Inventor of analytic
geometry – ‘Cartesian
coordinates’
Corresponded with
Princess Elisabeth of
Bohemia (1618-1680)
The Cogito
The Cogito as an objection to the No-Self Theory.
Latin:
Cogito, ergo sum.
English:
I think, therefore I am.
or: I think, therefore I exist.
The Cogito
In the Meditations, Descartes never uses the
expression ‘cogito, ergo sum’/ ‘I think,
therefore I exist’.
In parts of other works (e.g., The Principles
of Philosophy), he does.
The Cogito
“This piece of knowledge – I think, therefore
I exist – is the first and most certain of all
to occur to anyone who philosophizes in
an orderly way.”
Principles of Philosophy, Part I section 7
The Cogito
I have just said that I have no senses and no body, and I am so
bound up with a body and with senses that one would think that I
can’t exist without them. Now that I have convinced myself that
there is nothing in the world—no sky, no earth, no minds, no
bodies—does it follow that I don’t exist either? No it does not
follow; for if I convinced myself of something then I certainly
existed.
Cogito v1
1. I am convinced that there is nothing in the world.
2. If I am convinced that there is nothing in the world, then I exist.
---------
: . I exist.
(adapted from Feldman 1986: 59)
The Cogito
But there is a supremely powerful and cunning deceiver who
deliberately deceives me all the time! Even then, if he is deceiving me I
undoubtedly exist: let him deceive me all he can, he will never bring it
about that I am nothing while I think I am something.
Cogito, v2
1. I am deceived by something.
2. If I am deceived by something, then I exist.
-----------
: . I exist.
Cogito, v3
1. I think that I am something.
2. If think that I am something, then I exist.
------------
: . I exist.
(Feldman 1986: 60)
The Cogito
Cogito, v4
1. I think.
2. Whatever thinks exists.
---------
: . I exist.
The Cogito
Cogito, v4
1. I think. (‘think’ means roughly ‘am conscious’ or ‘am
undergoing mental activity’)
[If you think that you are walking/talking/deceiving
someone/surprising someone/holding a diamond, you
might be mistaken. But if you think that you are thinking,
there is no chance that you are mistaken. Inferential interp:
So (1) can be a metaphysical certainty for Descartes.]
2. Whatever thinks exists.
---------
: . I exist.
The Cogito
Cogito, v4
1. I think. (‘think’ means roughly ‘am conscious’ or ‘am
undergoing mental activity’)
2. Whatever thinks exists.
[If a thing has any properties or features at all, it exists. If
won’t have properties at all if it’s not there to have them. If it
doesn’t exist, it can’t have any properties or features at all.
Thinking is a property. So whatever thinks must exist.
Inferential interp: so (2) was a metaphysical certainty for
Descartes.]
---------
: . I exist.
The Cogito
Lichtenberg’s objection
“We should say ‘it thinks’ just as we say ‘it lightens’
[or ‘it’s raining’]. To say cogito is already to say
too much as soon as we translate it ‘I think’. To
assume, to postulate the I is a practical
requirement.”
Georg Chistoph Lichtenberg, The Waste Books, K
18.
Georg Christoph Lichtenberg
1742-1799, German
The Cogito
Lichtenberg’s objection, as stated by
Bertrand Russell:
“I think” is [Descartes’s] ultimate premiss. Here the
word “I” is really illegitimate; he ought to state his
ultimate premiss in the form “there are thoughts”
(1945: 567).
The Cogito
A reply to Lichtenberg’s objection:
According to Russell, when the cogito is carried out, what is certain ‘from this
perspective’ is just following proposition:
R There are thoughts or experiences
But more is certain than R. If only R were certain, then it wouldn’t be certain that
the following is false:
I, Zombie There are other people, who are all conscious and
have thoughts and experiences, and I exist, but I’m not
conscious and don’t have any thoughts or experiences
at all.
But it is certain that I, Zombie is false. That can be ruled out, from ‘in here.’ So
something more than R must be certain.
