A Dialogue on Personal Identity and Immorality
The Set Up
- Gretchen is dying. Se has been in a motor cycle accident
- She is lucid, but here organs are failing
- in order to convince Gretchen that she may have an afterlife, Sam needs to show that it is possible that she survives her death
- Gretchen maintains that the key to survival after death is that you need to be the same person
- In order to be the same person there must be appropriate memory and anticipation
The First Night
- What is the grounds our everyday assumption about personal identity
- how do you know that the person you saw today is the same person you had lunch with last week?
- what is it that remains constant to continual and preserves us as the same person
The Kleenex Box
- Designed to show us that we use term "identical" in tow different ways:
- "Exactly similar": This is what we mean when we speak of identical twins
- " Strictly Identity" 1=1 Peter Parker is identical to Spiderman
- We are concerned with Strict identity
If there is the same body, when there is the same person:
1. Gretchen is identical to her body.
2. Gretchen's body will not survive her death
3. Therefore, Gretchen will not survive her death
Sam's First Attempt
- If there is the same soul, then there is the same person.
- The problem is how can we know that a person has, the same soul?
- Two Options:
- Same body, same soul
- same characteristics, same soul
The Case of the Chocolates
- Objection to same body, same soul
- we only learn by experience that what is on the outside is correlated with what is on the inside.
- We have no experience of souls.
The Blue River
Objection to Same Characteristics, Same Soul:
- The Blue River always appears the same, but it never has the same water in it.
- It is possible for someone to act the same without having the same soul
- The Final Blow
- We cannot even know in our own case that we have the same soul we did when we were born, last week, or even a few seconds ago.
Gretchen’s Objection to Same
1. If Sam's view is true, then P1 is identical to P2 if and only if P1 and P2 have the same soul.
2. If Premise 1 is true, then judgments about personal identity are judgments about souls.
3. Souls are unobservable.
4. If souls are unobservable, then judgments about souls are groundness.
5. Therefore, Judgement about souls are groundless.
6. Our judgments about personal identity are not groundless.
7. Therefore our judgment about personal identity are not judgments about souls.
. Therefore, Sam's view is false.
The Second Night
Sam begins with 2 objections to Gretchen's view. The 1st objection is based on our experience of knowing who we are before we open our eyes?
1. If Gretchen's view is true, then P1 is identical to P2 if and only if P1 and P2 have the same body.
2. If Premise 1 is true, then no one can make a judgment about who he is without making a judgment about his body.
3. We do sometimes make judgments about who we are without making a judgment about our body.
4 . Therefore, Gretchen's view is false.
Sam's Second Objection
Based on Kafka's Metamorphoses
1. If Gretchen’s view is true, then it is impossible to remain the same person while having a different body.
2. It is not impossible to remain the same person while having a different body.
3. Therefore, Gretchen's view is false.
A New Approach
- The Blue River
- Baseball Game Analogy
- We say a baseball game is the same if it perserves a certain ordering or relation between its parts.
- The way we judge a person as the same person should be done not on the basis of parts but on the relation of its parts.
The Four -Dimensional View of Persons
- A person is a collection of parts called "person-stages"
- Person-stages are stretches of consciousness ( and any physical parts that accompany them)
- No two person -stages are identical to each other\ ( they happen at different times and places)
- a person P1 is identical to a person P2 if and only if they share all and onlty the same person- stages.
How are Person-Steges Related?
- The Memory Theory (MT):
- "The relationship between two person-stages that make them stages of a single person is just that the latter one contains memories of the earlier one."
- The Memory Theory & Survival: In order for Gretchen to survive her death, there would have to be a conscious person whose person-stages contain the memories of Gretchen's life.
Gretchen's Objection to MT
- The Hypnotist Case
- We need to be able to distinguish real memories from apparent memories
- Sam's suggestion is that the person with the real memories is the one who actually did the thing- that is, the one I who is identical with the person who did the thing.
Dave's Causal Theory of Memory
CMT: A collection of person-stages comprise a person if the stages are connected by Appropriately Caused Memory (ACM).
- Gretchen will survive if a conscious heavenly person exists with here Appropriately Cause Memories (ACM)
- If God creates a person in Heaven tat has the same mental states that Gretchen had at the time of her death, the Gretchen will be identical with that Heavenly person and so will have an afterlife.
Personal Identity and Immorality
Gretchen’s Objection to Sam’s Thesis
- God could have created more than one duplicate of Gretchen in heaven.
- If he did so, then it seems that by the Transitivity of Identity, the two Heavenly Gretchens would have to be identical - that is, they would have to be ONE Gretchen
- Transitivity of Identity : IF A=B, and B=C then A=C
Gretchen’s Reductio ad Absurdum
1. Sam’s thesis is true
2. HG1 is not identical with HG2
3. HG1 has Gretchen’s ACM
4. Therefore, HG1 is identical with Gretchen.
5. HG2 has Gretchen’s ACM
6. Therefore, HG2 is identical with Gretchen
7. HG1 is identical with HG2. (By the Transitivity of Identity)
8. HG1 both is and is not identical with HG2.
9. Premise 8 is necessarily false.
10. Therefore, Sam’s thesis is false.
The Third Night
- After getting stuck on problems of the afterlife the previous night, they go back to simply trying to figure out the problem
The Case of Julia North
- Julia ran over by trolley while saving a child
- Julia’s body is destroyed, but her brain is good.
- Mary Frances Beaudine (the child’s mother) has a stroke while watching.
- Mary Frances’ body is good , but her brain is destroyed.
- Dr. Matthews transplants Julia’s brain into Mary Frances’ body.
- The resulting person had all of Julia’s memories and believes herself to be Julia.
- Everyone agrees that it is Julia that survives, except Mary Fraces’ husband.
Dave’s Objection to Gretchen’s View
1 The New Person is identical with Julia
2. If Gretchen’s view is true & the New Person is identical with Julia, then the New Person’s body is identical with Julia’s body.
3. The New Person’s body is identical with Mary’s body
4. Mary’s body is not identical with Julia’s body.
5. Therefore, the New Person’s body is not identical with Julia’s body.
6. Therefore, Gretchen’s view is false.
- She denies premise 1
- The New Person is Mary Francis Beaudine, but she survives deluded.
Dave’s Conventional Identity
- There are 2 Criteria by which we normal decide the issue of Personal Identity:
- Bodily Continuity
- Psychological Continuity
- In the case of Julia North, the criteria were not helpful.
- I this case, it is simply a matter of convention which we choose.
Gretchen’s Objection to Convention
- Suppose they were to take Gretchen’s brain and transplant it into a healthy body, and Dave convinces her she will be the survivor.
- She gets an upset stomach if she has aspirin, but the Dr. says it will save her a headache later.
- She takes the aspirin.
- The supreme court then decides that she won’t be the survivor - it will be the person whose body her brain goes into
Back to the MT
- It explains how it is possible to make judgments about personal identity without making judgments about bodies.
- It explains the importance of personal identity - what we value in a person, i.e., personality, belief, attitudes, convictions, etc.
- The Brain Rejuvenation Case:
- A new brain is made to exactly duplicate another in terms of psychologically relevant states.
- If Gretchen were to have such an operation would she be identical with the person who survives.
The Problem (Again)
- If two brains are crated, then it seems we have a case exactly like the one from the previous night.
- Brain A is a duplicate of Gretchen’s Brain
- Brain B is a duplicate of Gretchen’s Brain.
- If MT is true, then both Brain A and Brain. B are identical to Gretchen.
- But then by the transitivity of identity they are identical to each other
The Ad Hoc Suggestion
- Dave suggests we accept the following ad hoc suggestion:
- If one brain is created (Brain A), it is Gretchen. - If a second brain is created (Brain B), it is not Gretchen.
The Loss of the Virtues of MT
- Gretchen claims that although Dave’s view is not incoherent, it loses the advantages of the memory theory.
- One can no longer know who they are even if they can see their body, they need t have information about their brain,
- There is no reason to explain why Brain A should be more important to Gretchen than Brain B because they are psychologically indiscernible. They both have Gretchen’s character, memory, etc.
The End of Gretchen
- Dave begins to respond, but is cut short by Sam who tells him “It’s too late.”
Where Am I?
What is the point?
- An explanation of the possible answer and the problem with each to the question where am I, or where is the person located.
- Dennett wants to show that none of our simple theories of personhood are going to work
- The Supersonic Tunneling Underground Device is trapped under Tulsa, Oklahoma
- Dennett has been asked to dismantle the device
- The STUD released radioactive material that affects brain tissue.
- In order to disarm the STUD he must leave his brain behind
- Dennett’s brain is removed, and placed in a life-support system in Houston, Texas
- Radio links connect the neurons in his brain to the nerves in his head.
- There is no loss of information
- It is as if there is a mere stretching of nerves
Where is Dennett After the Procedure?
- Dennett is surprised to find that he feels as if he is where his body is
- He think “ Here I am in Houston, TX looking at my brain floating in a vat.”
- He names his Brain “Yorik,” his body “Hamlet” and he is ‘Dennett”
- When he switches the power off who is he then
- First Option:
Where Hamlet goes so goes Dennett
- This option seems to be refuted by the well-known brain switching thought experiment. If you were to switch your brain with another person, everyone agrees you’d go where your brain goes.
- Second Option:
Where Yorick goes, so does Dennett goes
- Dennett seems to be looking at his brain. His 1st person perspective seems to be located elsewhere
- He wonders if he were to commit a crime, whether they would just lock up his body, brain, or both.
- Third Option:
Dennett is wherever he thinks he is
- Is one’s point of view infallible? He thinks that the content of one’s point of view is not identical to the content of one’s point of view is not identical to the content of one’s thought or beliefs
- Example : Rides at Disneyland where you don’t move but you feel as if you are because of the scenes being played around you
- Sitting still in your car and think your moving when you actually aren’t
Is Dennett in Several Places?
- Perhaps he is scattered objects
- This leaves a couple of questions:
- Where are all of his parts?
- What is his current point of view?
Disarming the STUD
- He travels to Tulsa
- While working on the STUD, his radio receptors fail and he becomes disembodied
- His point of view switches to his brain in Houston, Texas
- He has no sense or now way to communicate
Is Dennett a Disembodied Soul?
- Dennett wonders if the switch in point of an argument for the existence of a soul which can travel instantaneously from one place to another
- Dennett awakens to find that he has a new body, which he names “ Fortinbras”
- His old body “Hamlet” died and is still lin Tulsa lying next to the STUD
- He feels exactly the same as before but his point of view has changed to the location of his new body
A Visit to Yorick
- When Dennett visits his brain in Houston he is surprised to learn the scientists made a duplicate of his brain as a computer
- The computer was run in tandem with Yorick for a while
- They all have the same outputs
- For some time he has been using the computer as his brain
- named the duplicate computer brain Hubert
- Dennett can switch between Yorick and Hubert with no noticeable change or lag with current mental operations
- The two brains are in sync , seems to be no doubt they either are, or controlling one person
- when he turns off the output from the brain who would he be?
Two Brains or Two People
- Dennett worries scientists will hook up the new brain to a new body
- Then who would he be?
- The scientist suggest he would be both
- Dennett worries how he would support two of him on his salary
- He takes the switches that allows him to go back and forth between Yorick and Hubert, so he will know if anything happens.
Where is Dennett?
Which, if any, of the theories is still standing?
- Same Body = Same Person?
- He has changed his body
- Same Brain = Same Person?
- He can switch back and forth between two brains
- Same Soul = Same Person?
- Whenever he turns off the connection between himself and his current brain, he
- Dennett is wherever he thinks he is?
- He has been wrong on several occasion he thought he was identical to Yorick, then Hamlet, then he thought he was Yorick when he was being controlled by Hunbert
- Dennett goes along quite happily for sometime occasional switching back and forth between his brain never knowing which he is currently hooked up to.
- However, he switches, and a new person - who has been “trapped” silently without a body and a voice appears
- The brains have diverged ever so slightly at first, but now are completely out of sync.
- There now seems to be two persons - each of whom believes themselves to be Dennett, but who are completely different
- Now each is aware of the existence of the other, they will both need their now bodies
- So the question is …..
Where is Dennett ???
The Paradoxes of Time Travel
What is the point?
- Lewis wants to show that some of the seemingly paradoxical aspects of time travel are not paradoxical at all - they are just strange!
What is Time Travel?
- Time travel involves a discrepancy between time and time.
- Any traveler departs at a certain time, travels for a certain time, and arives at a certain time.
- However, for the time traveler the separation in time between departure and arrival does not equal the duration of his journey.
- Lewis accepts the Four-Dimensional view Persons.
- He also does not think of space as separated from time, rather there is one thing - Spacetime.
- Change is the qualitative difference between temporal parts of something-things without parts cannot change.
- How can the same even be separated by two Unequal Amounts of Time?
- The arrival of Tim at 1920 is separated from his departure ain 2007 by 87 years AND by a mere 1 hour. How is this possible?
- Distinction between External Time and Personal Time.
- Roughly that which is measure by the time traveler’s wristwatch.
- More precisely, it is not time at all, but plays the role of time in the person’s life. It is that which assigns coordinates to the person’s life so that regularities hold which match those that commonly hold with respect to external time.
- His hair grows, memories accumulate, infant stages are followed by child stages, and later senile stages, etc.
Personal Identity: the time traveler who travels into the past and talks to himself looks like 2 persons - how is it that they are one and the same person?
- Four-Dimensional theory of persons
- It is two temporal parts of a person that are present at the same time - not two persons.
- The time traveler’s stage are connected in the same way everyone else’s stages are by - mental connectedness and continuity.
- The time traveler’s stages causally connected - the later stages in his personal time are caused by the earlier ones
- It seems as though time travel involves Backwards Causation - that thing in the future cause things in the past to happen. But he past is fixed and unchangeable
- Time travel does involve backwards causation, but there is no contradiction - what happens in the past does not both happen and not happen.
- There is a disagreement between “ earlier and later” in external and personal time for the time traveler.
- It seems that at least some Time Travel must involve Causal Loops - uncaused information preserving circuit in time. But Casual Loops are impossible - ever effect must have a cause.
- They are not impossible, just strange.
- Example of the time traveler who tells himself how to make a time machine - his older self knew because his younger self had been told the information. Is younger self knew ( after the conversation) because his older self had told him. Where did the information come in the first place? There is no answer.
-The Grandfather Paradox: It seems that a time traveler who travels back into the past is as able as anyone to do things, so he must be able to change the past. For instance, Tim should be able to travel to the past and kill his grandfather. However, the past is fixed and unchangeable.
The Grandfather Paradox
1. If time travel is possible, then Tim can kill his grandfather because he has the ability, opportunity, and motive.
2. If time travel is possible, then Tim cannot kill his grandfather because the past is fixed.
3. Therefore, if time travel is possible, Tim both can and cannot kill his grandfather.
4. Therefore, time travel is impossible
- Lewis claims the argument equivocates on the word “can” in premises (1) and (2).
- In one sense, it is correct to say that Tim can kill his grandfather - he has the ability. In the way that Lewis can speak which Dutch - ability does not imply success
- In the other sense, it is correct to say that Tim cannot kill his grandfather. It is logically impossible that grandfather live and not live.
- The world where time travel take place would be a strange world - perhaps very different from the way we imagine our world to be
- However, it is a possible world - time travel need not be paradoxical