MovieChat Forums > Reign in Darkness (2002) Discussion > Be my baby

Be my baby

posted 17 years ago by tripleaaa7
5 replies | jump to latest

4/23/06

What Is It Like to Be a Bat?

Thomas Nagel

- What is the point
- Nagel argues that current theories that attempt to reduce th mental to the physical fai because they cannont account for the uniquely subjective experience of consciouness

The Mind Body Problem
- How are the mind and body related?
-The Substance Dualist says they are two completely separated substances that unite while a human being is alive
- The Non-Reductive Physicalist say that the mind is produced by having certain brain states, bt the mind not reducible to those states.
- The Reductive Physicalist says that the mind is identical to the brain or certain brain states.
Nagel’s Aim
- Nagel’s argument is directed at the Reductive Physicalist
- He is going to claim that there is something special about consciousness that cannot be explained by mere physical processes
The Claims of the Reductive Physicalism
- There is nothing that is not a physical substance
-there are no immaterial minds, angels, spirits, ect.
- All mental states are ultimately reducible to brain states. That is, mental states just ARE brain states
-Even though we cannot now understand how mental states rduce to physical states, with the development of neuroscience we will come to understand more and more about how the reduction works
Qualia
- The term ‘Qualia’ refers to the phenomenological feel of experience, or as Nagel puts it “the what it is like” of our internal states
- Ex. What it is like to eat peanut butter or marmite.
The Qualia of Consciousness
- If all experiences have a phenomenological feel, then it seems that consciousness has one too.
- There is a what it’s like to be you
- There must be a what it’s like to be a bat
- We can never understand what it is like to be a bat for a bat. No amount of facts about bats will help with this.
- We will have no concepts by which we ca understand how a ting so radically different from us experiences the world.
What it is like to be a bat?
1. If bats have conscious experiences, then there is something that it is like to be a bat.
2. Knowing all the physical fact about bats will never allow you to conceptualize what it is like to be a bat (for the bat)
3.Therefore, no reductive physicality account can explain all of what it is to ave a mind on consciousness.
The Essentially Subjective Nature of Consciousness
- Consciousness is different from other things that we might think are reducible to some more fundamental level (like physics).

-Normally, a reduction leaves out the subjective nature of a thing and tries to get closer to what is objectively true of that thing
- The lightning example:
- When we want to get aclearer on what lightning is we abstract from any particular experience of lightning and reduce it to its physical components
- Lightning appears to us as flashes of bright white across the sky.
- But lightning has an objective character that is independent of the kind of creature tat is experiencing it
- Consciousness seems to be different in an important way:
- The more objective you get about consciousness the further you seem to get what it essentially is.
Human Consciousness
- All human beings likely share the same type of conscious experience since we have the same perceptive and cognitive faculties
- However, we still think that there is a difference between what it is like to be me and what it is like to be you.
The Upshot
- It seems that consciousness can never be fully captured outside of the subjective standpoint of the conscious being
- This might indicate that the correct view of the mind-body relationship is Non-Reductive Physicalism or Dualism.

[–] tripleaaa7 17 years ago

Alexander Rodriguez
5/27/07
HIST 101
MWF 8:00-8:50
Chapter 13 Write-Up

Boom!!! The death toll left behind by the atomic bombs that dropped by the United States on Japan were astronomical. Over 100,000 thousand people either died from the injuries sustained or radiation poisoning. Some in the world saw this as genocide to take out the Japanese people, but others thought this was a necessary action to finally end World War II. Many historians to this day question whether just ending the war was the true intention of these nuclear weapons. In the society today, some may say this was terrorism committed by the US because they targeted the civilians instead of the armies. What kind of door has this event opened? Could it be the door that ends mankind? Now, I would just like to analyze the whole project of the atomic bombs and the decisions drop them.

This chapter begins with the test of the first bomb in the desert of Mexico. Through this atom bomb test, the United States confirmed the power of the bomb and what it could do before and after it went off. Of course, the scientists were overjoyed by this, even wiring the president the news of the test’s success. This brings up the moral question whether they should be happy about creating something meant to kill. They have created a new weapon 100,000 times deadlier than a gun, with enough of these atom bombs civilization could end in an instant. Also the cost of making 3 atom bombs was about two billion dollars. America could have used that money for something more beneficial to itself. This just tells you that the cost of war is high whether it is the cost of lives or money. These are just my thoughts on the idea of the cost and moral issue of the bomb.

The overarching topic is not the dropping of the bomb itself, but the decision to do so. The rational actor theory is used on Truman; this means that Truman gave the sole decision to drop the bomb. In my opinion, although the executive order of dropping the bombs had to be made by Truman, the whole question of being bombs in the first place was not his. If there were no secret plans to build the bomb, there would be no bombs in the first places to drop. The atom bomb project had started with the preceding president, Roosevelt, who kept his vice president Truman completely in the dark of the entire project. Wouldn’t it make sense to tell your number two man about what was later named The Manhattan Project?

Let us continue by discussing and analyzing the development process of the bomb itself. Roosevelt, in my opinion, should be used as the example of the rational actor instead of Truman. Initially, it was Roosevelt choice to finance the project after hearing what the top scientists such as Albert Einstein said about creating a fission bomb. It was Roosevelt that decided to start the Uranium Committee that became the S-1 when the priority of the bomb rose. It was Roosevelt who met with Churchill to discuss the political implications the bomb would have. The decision to drop the bomb was not made by Truman it was given to him following the death of Roosevelt. Your not going to spend two billion dollars on a project that you wouldn’t actually apply. Those that knew about the bomb before Truman, who found out about it when he became president, knew that there was no alternative but to use them. What was Truman supposed to do, keep these bombs in storage hoping they would never be used even though it was costly?

Try no to misinterpret me, I’m not saying that Truman had little to do with the decision, but the probable aftermath of dropping the bomb may also have led to it. Of course, the most openly stated reason to drop the bomb was to a finish to the war. The two atomic bombs did just that as the Japanese surrendered soon after. Many people believe the bombs didn’t just explode, but they sent a message to the world. Maybe the main objective of the bomb was to show the Russian of the militaristic power the United States had at their disposal. Some historians may say that instilling fear in others over the world, more specifically Russia, was the true intent of the atomic bombs. The whole arms race between the US and Russia began to start being dubbed the Cold War.

Today, almost everyone that knows of the atomic bomb lives in fear that another one can be dropped again. I believe that dropping atomic bomb in the present could lead to another dropping and another. Espe

[–] tripleaaa7 17 years ago

Alexander Rodriguez
5/27/07
HIST 101
MWF 8:00-8:50

Chapter 13 Write-Up

Boom!!! The death toll left behind by the atomic bombs that dropped by the United States on Japan were astronomical. Over 100,000 thousand people either died from the injuries sustained or radiation poisoning. Some in the world saw this as genocide to take out the Japanese people, but others thought this was a necessary action to finally end World War II. Many historians to this day question whether just ending the war was the true intention of these nuclear weapons. In the society today, some may say this was terrorism committed by the US because they targeted the civilians instead of the armies. What kind of door has this event opened? Could it be the door that ends mankind? Now, I would just like to analyze the whole project of the atomic bombs and the decisions drop them.

This chapter begins with the test of the first bomb in the desert of Mexico. Through this atom bomb test, the United States confirmed the power of the bomb and what it could do before and after it went off. Of course, the scientists were overjoyed by this, even wiring the president the news of the test’s success. This brings up the moral question whether they should be happy about creating something meant to kill. They have created a new weapon 100,000 times deadlier than a gun, with enough of these atom bombs civilization could end in an instant. Also the cost of making 3 atom bombs was about two billion dollars. America could have used that money for something more beneficial to itself. This just tells you that the cost of war is high whether it is the cost of lives or money. These are just my thoughts on the idea of the cost and moral issue of the bomb.

The overarching topic is not the dropping of the bomb itself, but the decision to do so. The rational actor theory is used on Truman; this means that Truman gave the sole decision to drop the bomb. In my opinion, although the executive order of dropping the bombs had to be made by Truman, the whole question of being bombs in the first place was not his. If there were no secret plans to build the bomb, there would be no bombs in the first places to drop. The atom bomb project had started with the preceding president, Roosevelt, who kept his vice president Truman completely in the dark of the entire project. Wouldn’t it make sense to tell your number two man about what was later named The Manhattan Project?

Let us continue by discussing and analyzing the development process of the bomb itself. Roosevelt, in my opinion, should be used as the example of the rational actor instead of Truman. Initially, it was Roosevelt choice to finance the project after hearing what the top scientists such as Albert Einstein said about creating a fission bomb. It was Roosevelt that decided to start the Uranium Committee that became the S-1 when the priority of the bomb rose. It was Roosevelt who met with Churchill to discuss the political implications the bomb would have. The decision to drop the bomb was not made by Truman it was given to him following the death of Roosevelt. Your not going to spend two billion dollars on a project that you wouldn’t actually apply. Those that knew about the bomb before Truman, who found out about it when he became president, knew that there was no alternative but to use them. What was Truman supposed to do, keep these bombs in storage hoping they would never be used even though it was costly?

Try no to misinterpret me, I’m not saying that Truman had little to do with the decision, but the probable aftermath of dropping the bomb may also have led to it. Of course, the most openly stated reason to drop the bomb was to a finish to the war. The two atomic bombs did just that as the Japanese surrendered soon after. Many people believe the bombs didn’t just explode, but they sent a message to the world. Maybe the main objective of the bomb was to show the Russian of the militaristic power the United States had at their disposal. Some historians may say that instilling fear in others over the world, more specifically Russia, was the true intent of the atomic bombs. The whole arms race between the US and Russia began to start being dubbed the Cold War.

Today, almost everyone that knows of the atomic bomb lives in fear that another one can be dropped again. I believe that dropping atomic bomb in the present could lead to another dropping and another. Eventually the bombings may beginning a nuclear war that would end humanity. The decision not only effect the past, but it has lain the seed of nuclear weapons of the present. In closing, the weapon of mass destruction of today are sign of national power, and they will continue to be built until peace can be achieved.

[–] tripleaaa7 17 years ago

Persuasive Speech

Every measure of precaution must be taken in order for this countries safety. I’m firm believer that our government must make sacrifices to achieve the greater good. If collateral damage is necessary for the safety of this nation, then so be it. I assuming the majority of you disagree with the way our president has dealt with the overarching terrorism issue. However, I believe one of his decisions took a huge step forward national security. This is the US Patriot Act, which has stirred up some controversy in the past year. To clarify, the US Patriot Act give the government the ability to monitor telephone conversations, emails, records, etc. which would make it difficult for terrorist actions to be committed on domestic soil. I wholeheartedly would agree with this plan, but according to recent polls done by various political site and magazine only 50% of Americans would agree with me. Those against it believe that the Patriot Act would take away their civil liberties, thus giving many Americans the impression they are losing their rights from the government especially the rights of privacy. This is the collateral damage I was talking about. Today, I would just like to tell you why it is necessary for all of us to adopt a favorable stance on the Patriot Act. If you care, about your own life as well as those of your fellow American you will agree with me.

Following the 9/11 terrorist attacks, the United States citizens felt vulnerable. Many asked the question how something like this could happen. According to www.romm.org, after further investigation of the attacks it was widely speculated that the US government knew of this attack beforehand, but they disregarded it on the basis of lack of evidence. As a result, approximately three thousand people lost their lives that day and a sense of insecurity tingled down every American‘s spine. Of course, the American people were quick blamed the government for its lack of investigation of these attack threats. I know this story is sort of cliché, but it’s a perfect example that if the government knew more something could have been done. We can’t change the past, but we can shape the future?

The Patriot Act is the perfect solution to insure that a cataclysmic event like this will never occur again. By supporting the this act, your decreasing the likely hood of another terrorist attack. The Act would cultivate cooperation between CIA and FBI, thus allowing the facilitation of information to narrow down possible domestic threats. It would facilitate the detection and prevention of the money laundering and the financing of international terrorist organizations. Protecting of the borders, by increasing the difficulty for anyone entering the country that is suspected of or related in any way to terrorism. Also any aliens in the country within the country already that have suspect terrorist ties shall be detained until it be deemed safe for them to reenter American society. Your probably thinking that taking away these particular individuals’ freedom is wrong without prior conviction, but like I said before just because there is little evidence there is still reason to investigate. The government does not want to commit the of carelessness again. Its about being better safe than sorry. As said before the side criticizing the Patriot Act fears that it gives the government too much power allowing it to violate American’s 4th Amendment rights.

[–] tripleaaa7 17 years ago

Sources

<http://www.mrdowling.com/707-leaders.html>;

<www.amazon.com>

<www.strategypage.com/militaryforums/47-880.aspx>;

<www.fatima.org/essentials/whatucando/communismalive.asp>;

<www.csun.edu/~kaddison/kraus.htm >

[–] tripleaaa7 17 years ago

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

The Challenge
- 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

Gretchen's View
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

Soul Swapping
- 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).

Sam's Thesis:
- 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.

5/2/07

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.

Gretchen’s Response
- 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.

Gretchen’s Objection
- 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.”

5/7/07

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

STUD
- 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

The Procedure
- 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

3 Options
- 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

Fortinbras
- 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

Hubert
- 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
becomes lifeless.
- 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

Divergence
- 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 ???

5/9/07

The Paradoxes of Time Travel
David Lewis

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.

Some Assumption
- 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.

1st Paradox
- 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.
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

3rd Paradox
- 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.

4th Paradox
- 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.

5th Paradox
-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

Equivocation
- 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.
Conclusion
- 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