Archive for the ‘David Lewis’ Category

Anticipation and the Extreme Claim

Wednesday, November 23rd, 2011

The Apparent Rationality of Prudential Concern

Consider the following apparently straightforward inference:

I do not expect to die soon. Therefore I expect to be alive in the future. I expect I will have experiences in the future. I anticipate having experiences in the future. Because experiences can be pleasant or unpleasant, I have reason to care about the quality of those experiences.

Notice the flow of argument: from a straightforward prediction of fact—that my death is not imminent—and the seemingly innocuous observations that persons persist through time, that persons have experiences, and that experiences vary in quality, to the conclusion that I have a reason to care about the quality of my future experiences. The steps in the argument seem innocent and deeply familiar. These ideas are so closely linked as to seem inseparable.

I suggest they seem inseparable because the core concept of a person is that of a subject of experience that persists through time. Because experiences can be pleasant or unpleasant, we think a subject has reason to care about their quality in the future.

By “subject of experience” I just mean whatever has experiences. I am not claiming that the concept of a person is that of a Cartesian ego, or a spiritual substance, or a biological organism, or its brain, or any sort of psychological entity. I claim only that the concept of a person is of something that has experiences. This claim is uncontroversial.

The above argument illustrates how a motivational idea—having a reason to care about something—can be embedded in what appears to be a straightforward factual description. (more…)

Kolak: I Am You

Friday, September 30th, 2011

People who think deeply about the puzzle cases of personal identity have come up with a variety of bold and radical responses. Like Alexander hacking through the Gordian knot, Parfit wielded an analytical scalpel to divide personal identity from what matters in personal survival, reaching the conclusion that ordinary survival is about as bad as being destroyed and replaced by a replica. Robert Nozick was so impressed by the difficulties posed by fission cases that he decided personal identity must depend on extrinsic factors: you are identical to whatever person is your closest continuer at any future time, a thesis with the odd consequence that, if your closest continuer after fission dies, you may suddenly find yourself being someone who until that time was someone else, your second-closest continuer. David Lewis’ solution to was to abandon the tried-and-true principle that persons can be counted by counting heads. Since there are two persons after fission, there were two all along, even though, before fission, they occupied the same body and were unaware of their duality. (Bizarre though it sounds, I support Lewis’ solution as one that inflicts the least damage to the traditional concept of a person.) Thomas Metzinger’s analysis led him to conclude that “no such things as selves exist in the world.”

In his book, I am You, Daniel Kolak offers yet another radical theory of personal identity: There is only one person, and that person is all of us.  What are commonly understood to be boundaries between individuals, he says, do not “merit the metaphysical significance ordinarily accorded to them.”

Our borders do not signify boundaries between persons. We are all the same person. [Kolak, 2010, p 1] (more…)

Gappy Things That Branch and Change

Thursday, January 14th, 2010

IdentityImagine, in the early days of books, a small library consisting entirely of original manuscripts.  Some of them are very old, and have been attacked by mice.  Some have deteriorated so much that their pages crumble to dust when the custodian of the library tries to read them.  He mourns the loss of these books, and contemplates the inevitable decay of the remaining books with sorrow.  To be sure, new manuscripts are occasionally added to the library, but they cannot replace the volumes that are lost forever.  This goes on until, one day, the young assistant librarian has an idea.  “This book will be unreadable in five years,” he tells his elder.  “But I can read it now.  If I copy the words of this book onto sheets of new vellum, and bind them in a strong new binding, we will be able to read it for many decades to come.”  The old librarian tenderly strokes the cracked spine of the crumbling volume, and shakes his head.  “What good is a copy?  It wouldn’t be the same book.”

In the previous post, I summarized one of Derek Parfit’s main arguments that personal identity – being the same person over time – is not what matters in survival.

Human fission – one person ‘splitting’ into two – is clearly imaginable.  It is physically possible, and is not far from being technically possible.  Parfit argues compellingly that fission would preserve what is important in survival.  Specifically, if Parfit knew that both of his cerebral hemispheres were about to be separately transplanted into two separate bodies, he would have the same rational justification for anticipating the experiences of both of the post-op survivors as each of us has for anticipating his or her own future experiences.  This, despite the fact that the original Derek Parfit ceased to exist when he was divided.  In this case, ceasing to exist is very unlike ordinary death.  Ceasing to exist just consists in the fact that the two post-op survivors are different persons from one another, and neither one is the same person as the pre-op Derek Parfit.  Loss of identity of this kind does not matter. (more…)