Parfit on Identity and Continuity

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• Parfit is concerned to address whether we really need a theory of identity to answer important questions about the self, or rather whether we can get by with something else. He will argue that we can drop identity and use psychological continuity as our important and relevant theoretical concept.
• First, note that we should not be surprised that some things lack answers to all identity questions. We might conclude there is no interesting answer to a question like, is England the same country before the Magna Carta and after WWII. So, we should be open to the prospect that some human personal identity questions might have no answer.
• One argument that there should be answers to all our PI questions could go something like this: each experience either is mine or is not mine. So, there should always be an answer about whether some agent (which presumably has experiences) is me or not.
• Some thought experiments can cast doubt on this reasoning.
• What about division? Suppose that you could divide your brain. (Parfit means literally cut in half, but let us avoid the questions about which side has what skills, and stick with fission like an ameoba -- thus, assume you have an ameoba-like brain.) Then, each brain is transplanted to a new body. What happened to you? Are you (1) destroyed, (2) on of the two people, (3) both of the two people.
  • (1) Seems wrong. If you didn't have the other copy, you'd be very inclined to say you survived.
  • (2) is arbritrary -- which one are you?
  • (3) is our best option. But now note that this wrecks talk about personal identity, since there are two different objects that I want to say are the same person as one past object.
• Another thought experiment: I divide my mind, and then reunite the parts after each does some task. This suggests that the person has two series of thoughts, and then they reunite. There are two problems for PI: what is it to have two series of thoughts? What is it for them to reunite?
• Parfits suggestion: give up the language (that is, theory) of identity.
• But so much of our planning and so on is framed as being about identity. Parfit's response: this is true but is a contingent fact arising because in the past we did not have splitting and fusing minds. So, identity in some sense reliably tracked issues of survival and psychological continuity. But the prospect that we can start to divide the two things (continuity and identity) allows us to see that the former is not the essential thing at issue for most of our concerns (e.g., survival).
• Definition: q-memory: memory of something that may or may not be my past experience (that is, memory that does not presume identity).
• Definition: psychological connectedness: an intransitive relation of having overlapping memories.
• Definition: psychological continuity: a transitive relation of having a series of overlapping memories.
• Parfit considers other thought experiment cases. Fusion: one person joins into two. Extensive division: one person has a chain of ancestral and future "selves." Fissing and fusing folks: persons who divide and join. Immortal bodies with shifting personalities. In all such cases, Parfit argues we see psychological connectedness coming in matters of degree.
• Parfit wants to generalize: for each of us, our connnection to future selves is a matter of degree. Personal identity, an all or nothing relationship, must be abandoned as the relevant criterion for our concerns with things like survival, and replaced with psychological connectedness.
• In conclusion, Parfit makes a fascinating claim. Much of ethics is concerned with questions of egoism and altruism. Should I be concerned about myself alone, or others to some degree? But all of such considerations are based on assumptions of clear personal identity. If my future self is me only to some degree; if it has some psychological connectedness with my current self, but only to some degree; then it seems that egoism rests on a mistake. As a result, I should be attracted more towards accounts that weigh all interests equally, over those that tell me to weigh my interests alone or more heavily -- for after all, those future interests are "mine" only to some variable degree.