PHIL105:
The Big Questions
Trimester 3 - 2011
What is Philosophy?
• Using reason & rational
argument to answer the
big questions
• The big questions are:
– The very important ones
– Hard to answer even when
we have all or most of
the relevant facts
Introduction to
Personal Identity
PHIL105 – T3, 2011
Lecture 1
Personal Identity
• Who am I?
• What makes me the same
person through time?
• What happens to me if
I’m copied?
• What about people who
have their brains
chopped in half!?!
• Hard questions, even if
we have all of the facts
Terminology
• Numerical identity
– A (literally) unique thing
• Qualitative identity
– Looks, feels, tastes (etc) identical
• Essential properties
– Required for numerical identity
• Accidental properties
– Can change without affecting
numerical identity
Personal Identity & the
Afterlife
• It can comfort us to think that
our loved ones live on somehow
after death
• But what would that really entail?
Reincarnation
• You are reborn into a new body
after death
• PROBLEM: Reincarnations don’t
seem to be the same person
Resurrection
• You (and your body)
come back to life
after you die
• PROBLEMS:
– Need an earth-like
place to go to
– If we’re recreated
exactly the same,
we’ll just die again
– Some of your atoms
will be part of other
organisms
Soul Liberation
• When we die, our soul
leaves our body to live on
somewhere else
• PROBLEMS:
– What, exactly, is a soul?
– What would your soul be like?
– Is a soul just the hard drive that our
memories, beliefs, and personality are
written on to?
– Is your soul without your body really you?
Cryogenics
• Being frozen until
medical advances
can fix all your
ailments
• PROBLEMS:
– Technological risk
– The brain may be too damaged
– Ice-cream headache
Cyborgs
• Use technology
to keep us
alive!
• PROBLEMS:
– Will it ever
work?
– How will we
know?
Personal Identity & the
Accident Victim
• Brain damage and
amnesia could
drastically
change what a
person is like
• But, would it
change who they
are?
COMINS
• Continuity of
the Mental Is
Necessary for
Survival
• VERDICT: Mr Edward’s son has not
survived the accident
• PROBLEM:
– How much and what type of ‘the
mental’ has to continue and how must
it continue?
CEBINS
• Continued Existence of
the Body Is Necessary
for Survival
• VERDICT: Mr Edward’s
son has survived the
accident
• PROBLEM:
– This may be necessary,
but is it sufficient for a
person to survive?
CESINS
• Continued Existence of
the Soul Is Necessary for
Survival
• VERDICT: Mr Edward’s son
has survived the accident
• PROBLEM:
– If it’s not the body or the
mental… what, exactly, is
the soul again?
Summary –
What Makes Us Survive?
•
•
•
•
•
•
•
Continuation of mental
Continuation of body
Continuation of soul
A combination
Has Martha’s Mum survived?
Has Edwards’ son survived?
Maybe we don’t survive?
Philosophy Clinic:
How to Argue that a Theory is
the Best Theory
• Explain the main theories and their main
strength
• Apply the theories to real and whacky examples
• A good theory will give an answer in each case
(who is the same person?)
• The best theory will give the right answer for a
good reason in most of the cases
• Good reasons for right answers are generally
consistent with our reflected-upon intuitions
• But you can also explain why some particular
intuitions are wrong (and your theory is right)
The elusive ‘I’
• Who here thinks
they exist?
• Cogito ergo sum
• Meditation time!! ??
• Lets ‘find
ourselves’
• Where am ‘I’ ?!?!
For Next Time
• Read:
– Law, Stephen: Brain Transplants,
‘Teleportation’ and the Puzzle of
Personal Identity
– Parfit, Derek: Divided Minds and the
Nature of Persons
More on Personal
Identity
PHIL105 – T3, 2011
Lecture 2
Personal Identity
• We want our theory to provide
answers to questions like these:
• What makes me me?
• What makes me the same person
through time?
Terminology
• Numerical identity
– A (literally) unique thing
• Qualitative identity
– Looks, feels, tastes (etc) identical
• Essential properties
– Required for numerical identity
• Accidental properties
– Can change without affecting
numerical identity
Sci-Fi Disclaimer
• The following ‘whacky’
thought experiments may
never be possible in real
life
– But, then again, they might!
• Regardless, a good theory of
personal identity should be
able to answer theoretically
possible as well as actually
possible problem cases
Animal Theory
• In essence, each
person is a living
animal
• What essentially
makes me me
through time is that
I am the very same
living creature as
the one in the
photos
Brain
Transplant
Case
• A brother and
sister have
their brains
swapped while
they sleep one
night
• Problem for the
Animal Theory
Brain Theory
• In essence, each
person is their
unique living brain
• What essentially
makes me me
through time is
that I have the
very same brain as
the ‘me’s in the
photos
Brain
Recorder Case
• This device resplices the existing
brain bits so that a
pre-recorded
personality (etc) can
be downloaded into
the (same) old brain
• Problem for the Brain
Theory
Stream Theory
• AKA: Psychological Continuity Theory
• In essence, each person is (the right
kind of) continuation of psychological
properties
• E.g. What MIGHT essentially makes me me
through time is that my memories are
psychologically continuous
The Reduplication Case
• This device makes perfect copies of
anything put in cubicle A (in c. B)
but the original is vaporized
• A new model also makes a duplicate
in cubicle C
• Problem for the Stream Theory?
Modified Stream Theory
• In essence, each person is (the right
kind of) continuation of psychological
properties
• Except when two or more people are
psychologically continuous (in the
right kind of way) from one person
– In which case, none of those later people are
the same person as the original person
The Duplicator Gun Case
• This device makes a perfect copy of
anything shot with it but it doesn’t
destroy the primary target
• Problem for the Modified Stream
Theory
They All Seem Wrong!
• The Animal Theory
– Gets the brain transplant and
recorder cases wrong
• The Brain theory
– Gets the brain recorder case wrong
• The Stream Theory (AKA the
Psychological Continuity Theory)
– Gets the reduplication and
duplicator gun cases wrong
• The Modified Stream Theory
– Gets the duplicator gun cases wrong
The Teletransporter Case
• You have been ‘teletransporting’ to work
(on a very distant planet) for 3 years
• You are at work when you are informed that
the ‘teletransporter’ really works like the
reduplicator (it copies & kills you)
• Do you get in and ‘teletransport’ home?
Why? Why not?
Divided Minds and the Nature
of Persons
• Derek Parfit
• Split-brain cases tell us
something interesting
about personal identity
• There are no ‘persons’ in
a split-brain case
• But there were no
‘persons’ before the
brain was split either
Why Chop Your Brain in Half?
• Suffers of severe epilepsy had
their corpus callosum chopped
in half to prevent seizures
spreading across hemispheres
• This means that the two halfs
of the brain cannot
communicate directly with
each other
• The resulting body acts as
normal in most cases and
suffers from less debilitating
seizures
The Experiments
• Left hemisphere
controls right eye &
hand (& speech in
right-handers)
• Using a special
technique, each
hemisphere was
exposed to a
different stimuli
• Each hand
responded as though
there is a separate
stream of
consciousness in
each hemisphere
More Info on the Actual
Split-Brain Experiments
• A picture is flashed in the
left visual field (for a
right-hander) so fast that
the right eye can’t see it,
but the left eye can.
• When asked, the person says
they couldn’t see the
picture
• But the ‘locked-in’ right
hemisphere did see it!
What ‘Goes With’ What?
• When asked to
point to the
picture that
‘goes with’
what they
see…
• Each hand goes
for a different
picture!
Does Each Hemisphere Know
about the Other One?
• They seem to ignore or be unaware of
each other
• Before the op. patients can name objects
on both sides, but only on one side after
the op.
• Interestingly, they
don’t complain about
the loss
The Ego Theory
• What essentially makes me
me through time is that all
of the ‘me’s are the same
subject of experiences (ego)
• What unites the many
experiences I have had in
my life is that I was the one
having them all
• The Cartesian View is an
example of this (my ego is
my soul)
The Bundle Theory
• We cannot explain our survival
through time by referring to a
‘person’
– Because no ‘person’ (subject of our
experiences) exists!
• There are just bundles of mental
states (experiences) tied together
by the causal relation of memory
(experiencing remembering
previous experiences)
• We call these bundles ‘lives’
The No Self View
• Buddha was the first
bundle theorist
• His No Self View is a
type of bundle theory
• People have ‘nominal
existence’ (we
sometimes talk as if
they exist), but only the
parts that make them up
really exist
Parfit: What We Believe
Ourselves to Be
• Science tells us that:
– There is no evidence for the Ego
Theory
– There is evidence for the Bundle
Theory
• Most of us believe something like
the Ego Theory to be true
• Unfortunately, most of us hold
false beliefs about who we are!
• Me: But does science tell us that?
Replacing Your Cells Case
• A high-tech alien is going to
replace some of your cells
with identical replicas (all at
once)
• If it changes 1% of your cells,
are you the same person?
• What if it changes 100% of your
cells?
• There are answers to these qns
How We are Not What We
Believe
• How could we even know if 49% or
50% (or whatever) replaced cells is
the right place for the line?
• It is implausible that a few cells
will make the difference in the
Replacing Your Cells Case
• But that is what our natural
beliefs/intuitions force us to say!
• Therefore, we should embrace the
Bundle Theory
Bundle Theory Applied
• When applied to all of the cases, the
Bundle theory rejects the question, ‘what
happens to you?’
• The Bundle Theory can explain what
happens, but it doesn't refer to persons
(because they don’t really exist)
• If ‘50% of your cells are replaced,’ then
50% of that bodies cells are replaced
• You don’t end or survive because you
were never there in the first place!
• These cases only raise worries because
we don’t properly understand the nature
of persons
PARFIT: Split-Brain Cases
and the Ego Theory
• The Ego Theory says that all of
the experiences in the splitbrain case are being had by the
one ego/person (but in 2
streams)
• The Ego Theory is wrong
because it ignores the disunity
between the two streams of
consciousness
• The ego can’t just split in two
– Because it is supposed to be the
one unique persisting essential
element of a person
PARFIT: Split-Brain Cases
and the Bundle Theory
• On the Bundle Theory, bodies
normally have an awareness of
having several different
experiences at any one time
– There is no ‘I’ (an independently
existing & persisting thing)
required for the explanation
• In the split-brain case, there
are two separate states of
awareness of experiences
– But neither of those states is a
unique, independently existing &
persisting ‘I’ (they don’t exist)
Parfit: Split-Brain Cases 1
• While both the Ego Theory and
the Bundle Theory can explain
our normal awareness of
experiences…
• Only the Bundle Theory
provides a good explanation
for the split-brain cases
• Combined with the lack of
scientific evidence for the Ego
Theory, we should accept the
Bundle Theory
• Which means that our belief in
our persisting ego/self/I is
false!
Parfit: Split-Brain Cases 2
• When someone’s brain is divided,
two streams of consciousness are
created
• Neither of the streams is the same
person as the original
• But, this is just like ordinary
survival!
– We are just bundles of mental states
tied together by remembering what the
previous experiences were like
– So, with every new experience, who we
are changes (our old numerical
identity dies!)
For Next Time
• Get ready to discuss:
– The Good Life
• Read:
– Singer, Peter (ed.) (1994). Excerpts of
Ultimate Good, in Ethics, pp. 199-205,
211-242, Oxford University Press.
(Read all except Nozick, pp. 228-229)