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Introduction to Personal Identity
Lecture 7
Dan Turton
• Office: MY715• Office Hour: Thurs 2:10-3:00pm• Email: [email protected]
• Phone: 04 463 5233 x 8651
Personal Identity Essay Question
• What is the best theory of personal identity and why?
• Explain and evaluate at least two common philosophical theories about personal identity, including ‘psychological continuity theory’.
• Apply these theories to at least one ‘whacky’ thought experiment and the real-life split-brain experiments as part of your evaluation.
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
• PROBLEM:– Need an earth-like
place to go to– If we’re recreated
exactly the same, we’ll just die again
Soul Liberation
• When we die, our soul leaves our body to live on somewhere else
• PROBLEMS:– What, exactly, is a soul?– If the soul is just the mental, then how
can it live on?– Is my soul (without my body) human enough to be me?
Cryogenics
• Being frozen until medical advances can fix all your ailments
• PROBLEMS:– Technological risk– The brain may be
too damaged
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?
Take Home Lessons
• Please don’t do any life-after-death experiments when you get home!
• He’s our best bet for life after death, so start saving now!
• The beauty of youth is fleeting – enjoy it while you can!
For Next Time
• Read:– Baggini, Julian: The Elusive I (p8)– Law, Stephen: Brain Transplants,
‘Teleportation’ and the Puzzle of Personal Identity (pp9-14)
• Get ready to discuss:– Two promising theories and the ‘whacky’
thought experiments that seem to refute them
Bodily Continuity
vs Psychological
Continuity
Lecture 8
Personal Identity Essay Question
• MAIN QUESTION: What is the best theory of personal identity and why?
• INSTRUCTIONS: Explain and evaluate at least two common philosophical theories about personal identity, including ‘psychological continuity theory’.
• INSTRUCTIONS: Apply these theories to at least one ‘whacky’ thought experiment and the real-life split-brain experiments as part of your evaluation.
Personal Identity
• We want our theory to be able to provide answers to questions like these:
• What makes me me?• 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!?!
The elusive ‘I’
• Who here thinks they exist?
• Cogito ergo sum
• Meditation time• Lets ‘find ourselves’
• Where am ‘I’ ?!?!
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 slept 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 re-splices 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?
Take Home Lessons
• This course is about tackling the big questions, not necessarily the relevant ones
• If you do something stupid quickly get soo drunk you lose your memory of it – then it wasn’t you who did it
• With a duplicator gun we could win the world cup
For Next Time
• Read:– Nozick, Robert: Personal Identity through
Time (pp15-26)
• Get ready to discuss:– Nozick’s more complex views on this topic
The Closest Continuer Theory
Lecture 9
Some Theories of P.I.
• CEBINS: Continued Existence of the Body Is Necessary for Survival– E.g. The Brain Theory
• CESINS: Continued Existence of the Soul Is Necessary for Survival– E.g. The Soul-Pellet Theory
• COMINS: Continuity of the Mental Is Necessary for Survival– E.g. Psychological Continuity/Stream Theory
• E.g. You have to remember being your previous self (and that previous self has to remember being a more-previous self and so on)
Nozick: Personal Identity through Time
• Bernard Williams’ main Principle for P.I.:
• The numerical identity of something cannot depend on facts about other things
• Because what makes you uniquely you is not dictated by facts about things other than you
The Vienna Circle (TVC)
• 3 of the 20 original members continued meeting in Istanbul
• Later, they hear that all of the other TVC members are dead and considered themselves as ‘TVC’
• Later still, they hear that 9 other members have been meeting in New York the whole time and realised that they were just an offshoot of the real TVC in NY
• Thus Williams’ principle is false
Closest Continuer Theory (CCT)
• What essentially makes me me through time is that I am always the (one) closest continuer of the previous me
• And that the closest continuer (CC) is close enough– I.e. too dramatic a change of an
essential property (even) in the cc will mean that the cc is not numerically identical with the original
The Vienna Circle (TVC)
• Later, the 3 hear that all of the other TVC members are dead and considered themselves as ‘TVC’– Because they are the closest continuer
of TVC
• Later still, they hear that 9 other members have been meeting in New York the whole time and realised that they were just an offshoot of the real TVC in NY– Because they are not the closest
continuer of TVC
The Ship Theseus
• A repaired ship is the CC of the original
• Until the old parts are all put together in ship B
More Specific on the CCT
• Being the closest continuer needn’t involve being qualitatively similar– Although it often will
• More important is that the CC is causally dependant (in the right kind of way) on the original– E.g. The CC has grown or developed out of the
original (or maybe) was caused by it
• There can be many factors that are relevant to being the CC, but they needn’t all be necessary (essential)
How Do We Discover the Dimensions of Closeness?
• Nozick: Introspect• We have intuitions about whether
something is numerically identical with something else
• We must analyse these intuitions to discover what makes something ‘closest’ to the original in each particular case
• PROBLEM: Intuitions might track accidental properties
The Duplicator Gun Case
• This device makes a perfect copy of anything shot with it but it doesn’t destroy the primary target
• CCT seems to work in this case
Modified Brain Transplant Case
• You’re dying of a heart attack, but your brain is transplanted into a healthy clone of your body
• The old body dies as the new one comes to life
• CCT says that the clone with your brain is now the real you
Conflicting Judgements
• What if our intuitions are different?• What if we disagree about what the
dimensions of closeness (the important properties) are?
• Nozick thinks we can eliminate most disagreement by comparing cases and going for consistency
• But maybe the CCT is too flexible
Brain Splitting Case
• You have ½ of your brain transplanted into a clone of yourself
• Both you and the clone live on with full psychological continuity
• CCT says that you are still you and the clone is a different person
Random Cosmic Occurrence Case
• A random chemical reaction on a distant planet creates a perfect copy of you exactly as you die– But not caused by you in any way
• CCT says it’s not you because it isn’t caused by you
Teletransporter Case Revisited
• You’ve been teletransporting to work (on a very distant planet) for 3 years
• Nozick: teletransporting probably destroys you because if Person A was not destroyed then Person B would not be the Closest Continuer– So on the CCT, Person B is probably not close enough
to Person A to be numerically identical to them
Mono-Relatedness & Jumping
• More specifically, CCT entails that numerical identity can only pass between pairs of closest continuer and closest predecessor
• Strangely, this allows ‘jumping’ if being temporally connected is not set as a dimension of closeness
Overlap Brain Splitting Case
• You have ½ of your brain transplanted into a clone of yourself
• Both you (A) and the clone (B) have full psychological continuity
• But you slowly die• Nozick/CCT says that A is you
until A dies, then you jump to B – depending on how long it takes A to die!
Overlap Brain Splitting Case 2
Nozick on the Overlap Problem
• The CCT is a good theory, but cases of overlap seem to show that it’s wrong
• The problem is that we want to claim that D is a later A, but we can’t when they overlap– Because D is closest to C, A is closest to B, and B
and C exist simultaneously so they cannot be numerically identical
3 Different Types of Theory of Personal Identity
1) Intrinsic Abstract Structural* E.g. Soul-Pellet Theory
2) Relational* E.g. Psychological Continuity Theory
3) Closest relative* E.g. Local Closest Continuer Theory and
Global Closest Continuer Theory
The Soul-Pellet Theory
• What essentially makes me me through time is that all of the ‘me’s have my one unique soul
• PROBLEMS:– What is a soul?– How does it know where to go in
the reduplicator case?– What if it didn’t pay attention and
lost your body?
Nozick’s Parting Shots
• CCT is the best, but it has major problems:– Overlap– weighting/lexicaltiy of dimensions of closeness
• There are no fixed facts to construct dimensions of closeness for people because:– The essential properties of unique individuals will
vary through time and across individuals– And, the essential properties of unique individuals
are “partially determined” by our own conceptions of what it means to be ourselves
For Next Time
• Read:– Parfit, Derek: Divided Minds and the
Nature of Persons (pp27-31)
• Get ready to discuss:– An introduction to the scientific findings in
split-brain cases and a discussion of what Derek Parfit thinks this means for personal identity
How Many People Am I?
Lecture 10
How to Argue that a Theory is the Best Theory in the Essay
• Explain at least 2 different theories• Apply the theories to examples
1st) Use a real-life example2nd/3rd) Use 1+ whacky thought experiments2nd/3rd) Use the split-brain case
• A good theory will give an answer in each case (who is the same person?)
• The best theory will give the right answer in most of the cases
• 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)
Closest Continuer Theory (CCT)
• What essentially makes me me through time is that I am always the (one) closest continuer of the previous me
• And that the closest continuer (CC) is close enough– I.e. too dramatic a change of an
essential property (even) in the CC will mean that the CC is not numerically identical with the original
More Specific on the CCT
• Being the closest continuer needn’t involve being qualitatively similar– Although it often will
• More important is that the CC is causally dependant (in the right kind of way) on the original– E.g. The CC has grown or developed out of the
original (or maybe) was caused by it
• There can be many factors that are relevant to being the CC, but they needn’t all be necessary (essential)
How Do We Discover the Dimensions of Closeness?
• Nozick: Introspect• We have intuitions about whether
something is numerically identical with something else
• We must analyse these intuitions to discover what makes something ‘closest’ to the original in each particular case
• PROBLEM: Intuitions might track accidental properties
The Duplicator Gun Case
• This device makes a perfect copy of anything shot with it but it doesn’t destroy the primary target
• CCT seems to work in this case
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 partition, each hemisphere was exposed to a different stimuli
• Each hand responded as though there is a separate stream of consciousness in each hemisphere
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 split-brain 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
• Read:– Puccetti, Roland: Brain Bisection and
Personal Identity (pp32-40)– Gillet, Grant: Brain Bisection and Personal
Identity (pp41-43)
• Get ready to discuss:– More views on what the split-brain cases
mean for personal identity
How Many People Am I?
Lecture 11
Why Whacky Thought Experiments & Unusual Real
Cases are Important• Why not focus on just real & normal cases?• All of the theories that we discuss give plausible
answers to the real & normal cases• So, all of these theories seem pretty good, but some
contradict each other! They can’t all be right (or best) – so which is the best?
• To find out, we use more unusual and even currently impossible thought experiments
• If a theory is truly correct, then it will have the right answer even in theoretical cases (cases that might never happen but could happen in the future or on other planets etc.)
How Many People in Split-Brain Cases?
• PARFIT: none– Bundle Theorist / No Self View– In fact, there was always none!
• PUCCETTI: two– Dual Persons Theory– In fact, there was always two!
• GILLETT: one– A mixture of theories– Obviously, there was only 1 before too!
How
Vis
ual F
ield
s
Rea
lly W
ork
The Actual Experiments
Brain Bisection and Personal Identity
Roland Puccetti
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!
Puccetti vs. Eccles
• Eccles: The sub-dominant hemisphere (SDH) is not conscious, – The SDH processes but doesn’t communicate – so
it’s like a dumb animal
• Puccetti: The SDH is conscious– When the whole of dominant hemisphere is
removed, people still consciously live on– The sub-dominant hemisphere does have
rudimentary language capacity, but it can’t control speech and often not writing
– E.g. Abstract concepts can be recognised• E.g. Being instructed to retrieve objects that ‘go with’
pictures – see hammer, retrieve nail etc.
What ‘Goes With’ What?
• When asked to point to the picture that ‘goes with’ what they see…
• Each hand goes for a different picture!
Hemispheric Conflicts
• Surely the two consciousnesses will argue all the time like siblings?
• Sperry: they experience very similar things, so will have similar tastes
• We perform lots of activities unconsciously (walking home etc)
• Bodily status often dictates primary drives like being hungry and both hemispheres have access to this info
• But conflicts can occur – e.g. wife beckoning and pushing away
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– Probably because the
dominant hemisphere doesn’t remember seeing the plant before
Hemispheric Self-Centeredness
• When asked how they managed to point out the key, participants (left brain) claim not to know or make up some story
• They do not admit to the presence of another self in their body!
• If either hemisphere knows, then it is definitely the SDH because it hears words come from it’s body that are not from itself
Two Minds in One Person!?
• Bogen: each of us “has two minds in one person”
• Puccetti: one person can’t have two minds unless we change our notion of ‘person’
• If we allow for two minds in one person then a person can simultaneously believe that he is seeing red and seeing blue, while also believing that he is not seeing red and seeing blue!
Two People from One Person!?
• How can chopping my brain in half create 2 people, when there was just one?– How do I know which is
the new one?
• Puccetti: Easy, there have always been two people in each of our bodies!
Lefty: ‘Pleased to meet
you’
Righty: ‘Please
d to meet you’
Dual Persons Theory
• In essence a person is a mind– Add in some kind of COMINS theory here– E.g. Psychological Continuity
• From the time of birth, each of our hemispheres start to specialise in certain tasks and develop distinct proficiencies, but…
• Because they are stuck in the same body, these two people have very similar personalities.– They have had very similar experiences and have
made very similar memories
Who am I?
• OK, two people in one body… but which one am I !?
• Puccetti: To even consider such a complicated question, you must be your dominant (verbally proficient) brain hemisphere
• Who will write your essay?– Hopefully your dominant hand & brain!
• But who painted my paintings?– Your SDH (right). So say thank you!
Brain Bisection and Personal Identity
Grant Gillett
Gillett on the Experiments
• The resulting behaviour would normally be thought of as 1 stream of consciousness per hemisphere
• But, in real life situations, the patients are pretty much normal – Probably because the hemispheres
do find ways to communicate– E.g. In real life, they would look at
things with both visual fields
Gillett on the Experiments 2
• What we should focus on is the one person who realises that they have performed strangely in the tests
• They don’t think that another person inside their body is messing things up for them!
• It’s important to note that we can’t tell what (or even if!) the right brain is consciously thinking
• We do lots of things without really consciously thinking about it – e.g. recognising colours
Gillett on the Experiments 3
• A mind is a conscious rational thinker– This involves self-ascribing thoughts which
involves “complex conceptual connections”
• The right brain by itself doesn’t have the language capacity to do this
• The best explanation is that one mind/person is having more trouble than it used to integrate all of the information its sensory organs gather
How Many People in Split-Brain Cases?
• PARFIT: none– We are a constantly changing bundle of
mental states so there are no ‘people’• PUCCETTI: two
– Each hemisphere has its own stream of consciousness (before and after brain-bisection)
• GILLETT: one– One mind is conceptually aware of
compiling our complex functioning (before and after brain-bisection)
Does Each Hemisphere Have Its Own Sense of Self?
• Michael Gazzaniga• Forty-five years of split-brain
research and still going strong– In Nature Reviews Neuroscience
• Each certainly can be independently aware of things
• But, no “clear-cut” evidence that each has a “full sense of self”
• But, the left hemisphere is more important in self-recognition
Recognising Yourself
Test on Friday!!
• See qn on Blackboard– It’s on David’s section: Consciousness &
the Mind/Body problem
• Do a practice run!• Any questions?
• Next week is Jay Shaw– Topic: Nature of Human Beings, Law of
Karma and Concepts of Harmony
