phil105: the big questions trimester 3 - 2011. what is philosophy? using reason & rational...

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

Topics

• Week 1: Personal identity• Week 2: The good life• Week 3: The meaning of life

Dan

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 untilmedical 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 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?

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

How

Vis

ual F

ield

s

Real

ly W

ork

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 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

• 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)