problems

1. what we take ourselves to be

Derek Parfit makes a distinction between two reductionist accounts of personal identity:

The Physical Criterion. What is necessary and sufficient for the continued existence of a person is the non-branching continuity of enough of their brain and body.

The Psychological Criterion. What is necessary and sufficient for the continued existence of a person is the non-branching continuity of enough of their psychology with an appropriate causal history.

A

Consider the cases described below and explain what each criterion predicts in each case. Please justify your answer.

1. A person is scheduled to undergo a procedure in which the brain is removed and placed in the body of a recently deceased donor. The person that ensues shares the same memories, personality traits, and intentions as the original person.

2. A “jewel” is a diminute computer implanted on the brain of a person early on in life. The jewel continuously monitors and mirrors the brain activity until it learns to replicate its patterns perfectly over time. A switch takes place in the early thirties whereby the biological brain is removed in order to let the jewel expand and take complete control with seamless continuity of consciousness.

   This is the case Greg Egan describes in “Learning to Be Me”.

3. A person steps on the teletransporter with the aim and expectation to travel to Mars. The scanner destroys the original brain and body, records the complete physical and psychological state of the person, and sends a signal to Mars where another device immediately reconstructs a replica of the original brain and body. The replica is psychologically continuous with the original person, and this continuity has an appropriate causal history.

   This is the simple teletransporter case Derek Parfit describes in Reasons and Persons.

4. A person steps on the teletransporter, but the scanner leaves the original brain and body intact. One replica is built on Mars, which is psychologically continuous and strongly connected with the original person and this continuity and connection has an appropriate causal history.

   This is the branch-line teletransporter case Derek Parfit describes in Reasons and Persons.

5. A person steps on the teletransporter just like in the simple teletransporter case, but there is a malfunction and the signal is sent to more than one place after the original brain and body is destroyed. Two replicas are simulatenously built on Venus and on Mars. Both are psychologically continuous and strongly connected with the original person and this continuity and connection has an appropriate causal history.

B

What matters in survival, according to Parfit, is not numerical identity but rather psychological continuity. Consider the following two variations on the simple teletransporter case:

1. You are told that there is a substantial risk of malfunction in the simple teletransporter case whereby the signal may be sent to more than one planet, maybe as high as 30%. You are offered the chance to minimize the risk of malfunction by paying more than twice as much what you would have paid to use the teletransporter.

   • Would it be rational for you to pay the premium according to Parfit?

   • Would you pay the premium?

2. You are given the choice between the simple teletransporter case and the branch-line teletransporter case. That is, you can decide whether to have the scanner destroy your body and brain and have your replica in Mars continue to live a rich and fruitful life or to have the scanner save your body and brain in which case you will live on for just a few weeks here on Earth.

   • What is the rational choice to make according to Parfit?

   • Would you make that choice?

3. Not only is there no risk of malfunction, but you know you can maximize the destinations to which the signal is sent if you bribe the technician. No one else will be negatively impacted by your action if you do. Once you bribe the technician, she will send the signal to five different planets resulting in the production of five replicas, all of whom will be psychologically continuous and strongly connected with you.

   • Would it be rational for you to bribe the technician according to Parfit?

   • Would you consider the bribe?

2. survival and identity

Identity and survival may come apart in cases of fission and fusion.

A

Consider David Lewis’ account of fission. Even before division, we had two persons, Alpha and Beta, who share all of their stages up to the time of division. Assess the following objections:

1. Before fission, there appears to be only one person in the room. When I promised to donate 1M if I win the lottery, I thought I made a promise to one person. Yet, according to Lewis, there are at least two as opposed to one person.

   • How many promises did I make?

   • How am I supposed to discharge my promise(s) if I win the lottery after fission?

2. How can I even know I made only two promises? On Lewis’s view, there may well be many more than two persons in the room.

   • Is there some way to constrain the number of persons in the room? Must it be a power of 2? Finite? Both? None of the above?

B

Consider a case of fusion. Alpha and Beta are two persons with two distinct bodies and and different psychological states. Though some complicated procedure, they are neurologically merged into someone, whose person stages are psychologically connected and strongly continuous with person stages of both Alpha and Beta. The post-fusion person stages have first-person access to many of Alpha’s and Beta’s memories, and a personality that is a combination of both.

1. Alpha and Beta appear to be the only persons in the room before the fusion takes place. Consider a person-stage emerging from the operation. How many persons does that stage belong to? Where were they prior to the operation?

2. Is Alpha identical to Beta?

3. Is the post-fusion person stage part of Alpha or Beta?

4. Suppose I promised Alpha and Beta 1M each if I win the lottery after fusion. Am I simply off the hook if I win the lottery after fusion? If not, how much money should I give a post-fusion person stage in order to fulfill my promise?