Monthly Archives: June 2015

I tend to think that the psychological and physical theories of personal identity are both insufficient. There are cases where psychological continuity wouldn’t count as identity (say, we find a way to duplicate brains), and cases where physical continuity clearly fails (for example, most people would equate a complete brain-wipe with death.)

But if we assume that our theories are determinative for our own identity, we could do the following: we find a young, healthy physical continuity theorist and an elderly, unwell psychological continuity theorist, and offer them the following deal: the psychological continuity theorist gives all of his or her money to the physical theorist, and we then reprogram the physical theorist’s brain to be an exact match of the psychological theorist. The psych theorist then gets to live in the physical theorist’s body, at least on the psych theory, and the physical theorist gets a lot of money. Both would think of themselves as continuing to exist, so it’s a win-win.

Suppose a famous statue, say, Michelangelo’s David, was in need of restoration. The marble under the base was rotting (let’s just assume marble can rot). So the restorers dig out the rotten section, a part that would be completely invisible, and find that it goes deep. They have to hollow out the legs and torso and pretty much the entire statue. They never touch the surface, and from the outside the statue looks exactly the same. All the marks of Michelangelo’s work are there, and every surface element is the way it is because Michelangelo sculpted it that way. But the inside is completely gone. To stabilize the statue they refill the inside with a powdered marble and some fine liquid adhesive, which sets, providing what is essentially a new marble interior that bonds perfectly with the shell of the statue. Though the surface layer is untouched, the vast majority of the statue’s mass has been replaced, but of course, it was mass that was never seen by viewers.

Is this the same statue?

Suppose instead that the surface of the statue is rotting. Restorers carefully, piece by piece, remove the surface, but only the surface layer (say, no more than 1cm of depth). They replace it with replica finished by contemporary restoration experts, who are, of course, highly trained sculptors. In the end, it would be very hard to tell the difference between the pre- and post-restoration statue. The great bulk of the statue, of course, is unaffected: it’s only the thin surface layer, the parts that Michelangelo touched, that are affected.

Is this the same statue?

The continuity of the statue in the first case is perhaps analogous to what psychological identity theorist, or those who hold that the person is the brain, would hold about persons. Though the vast majority of the matter is removed, the person or statue retains identity, because there’s a special, relatively small part, which carries what is essential to identity.

The continuity of the statue in the second case is perhaps analogous to what an animalist would hold: the majority of the mass of the statue is undisturbed, and the statue would be able to continue to support its own weight, just as the person’s body remains undisturbed, and is capable of carrying on basic functions, if the cerebellum were removed and replaced with a duplicate. The persistence of the major, structural elements is what’s important, not the small element that is commonly (though, according to the animalist, mistakenly) thought to maintain the identity of the statue or person.

My guess is that almost everyone would say that it is the same statue in case 1, because what makes it the David are the elements that Michelangelo worked on. So, again I’m guessing on general response, the convention concerning the meaning of “same statue” is probably tied into the marks made by the artist. In the second case, I think there’d be more disagreement. This would correspond to studies on what people think counts as same person; they generally think of persons as constituted by mental content.

One important thing to note: a poll is not the same as metaphysics, but a person is very different from, say, an electron. The term ‘person’ is the result of social agreement about language usage over many years. Persons were not discovered and discovered in the way electrons were, and what does and doesn’t count as a person or the same person is subject to a lot more force of convention than what does and doesn’t count as an electron. So we do need to be sensitive to common usage, because if we wind up with a version of ‘person’ that is strongly at odds with that usage, we may well no longer be talking about persons, but about some other thing that we have invented for the purpose of, say, a consistent philosophical position.

Persons across time could have identity, unity, or connectedness:

1. Identity: Person at time T₁ and person and time T_1+n are the same person. They are identical.
2. Unity: Person at time T₁ and person and time T_1+n re two parts of one larger cross-temporal entity. The two “time slices” are not identical to each other, but are component parts of one, four-dimensional thing.
3. Connectedness: Person at time T₁ and person and time T_1+n have some other relation which connects them: they may share memories, or bodily parts, or be connected by a chain of overlapping memories, or overlapping bodily parts, or they may hold the same “office,” that is, they may hold the same place in social or political or legal relations. They are not strictly identical, but they may be the same person for specific purposes: for example, perhaps psychological and physical continuity would be sufficient for legal responsibility; or mere physical continuity would be sufficient for continued ownership of goods, etc.

On some level, 1 is impossible. Nothing has absolute sameness across time; the platinum-iridium kilogram bar, for example, seems to have grown lighter (or its duplicates grew heavier.) People under go much greater change than platinum-iridum bars. Absolutely strict identity won’t work for them, so we have to decide if personal identity is carried by some subset of the things that the person is made up of, or is, contra the strict notion of identity, amenable to some changes in virtual any part, etc.

The unity answer doesn’t really help, because it already assume that person at T₁ and person at T_1+n are slices of the same person, and that’s what we need to get at. That is: how do I know that these two person-slices are slices of the same person? Surely, even a four-dimensional person has conditions which he or she cannot survive, and must come to be and cease to be at various points in time. The rotting corpse of Johan is, for most purposes, not Johan. Nor are the various bits of matter, floating around in the early universe, which will eventually make up Johan’s body.

Connectedness seems to be the area of investigation for sameness of persons. What are the conditions of connection needed for a person to be the same person as something that exists at another time? This is, indeed, where most of the theories come down: animalism, physicalism, psychological theories, all say that some part of their preferred section of the person must be preserved, though by no means the entirety of that part. So no animalist claims that the entire body must be preserved; they focus on continuity conditions for living organisms, and must make some arbitrary choices for beginning and end points. Thus, Olson claims that a person is dead even if her brain is still functioning and we have some system of communicating with that brain (say, a neural implant hooked up to audio input and output systems that allow speech and hearing) if her body has died. So a brain transplant, on this account, is the end of a person. A sudden and complete memory wipe is probably the end of a person on psychological accounts, even if the body persists and can be rehabilitated.

The question then becomes: why are we asking about personal identity or survival? Is it to apportion blame, legal punishment, ownership of goods? To re-identify loved ones? To know if my memories are in fact my memories, and not the memories of some other that I’ve inherited?

Notably, when we do legally punish, under the vast majority of systems of laws we only punish people believed to be, in some important sense, identical to the person who committed the crime. I don’t punish a twin for her sister’s crime, for example. And we want to be our friend, the very person who has identity with the person we previously identified as our friend, not someone who merely looks and acts like him.

So it seems that, for some purposes, a kind of identity is called for, though it will not be strict identity. Strict identity may be, as David Shoemaker says, “the reddest of herrings.” But identity, more broadly construed, is central to our concerns.