Thomas Metcalf

I've decided that brain persistence is necessary and sufficient for person persistence. This is not a view of personal identity per se, but I think it suggests a fairly plausible one, and I'll elaborate a bit later. For now, I want to say what's led me to this decision.

Reductionist views of person persistence seem to me to be almost inescapable. Lynn Baker's view of person persistence depending simply upon the persistence of a first-person perspective, independent of brain or pyschological continuity seems to me to be deeply unsatisfying. After all, by such a view, I have no way to tell whether the person typing the last word in this sentence is the same as the person typing the first word. We seem to think that we make reliable first- and third-person reidentifications fairly frequently, so I take part of what we mean by "person" to be something that can in fact be reliably reidentified. I believe this is strong support for reductionist views. (I think haecceity views fail for the same reason.)

Psychological continuity views of person persistence seem to suffer from a few problems. The most pressing of these, I think, is that they seem to require that a person's identity depend upon the identity of distinct synchronous persons. I'm thinking of the duplication problem here; suppose person A is destroyed while B and C, each with psychological continuity with A, are created. It seems that A must have survived, but there is no principled reason to say whether B or C is the next incarnation of A. And we can't say A has ceased to exist, either. Suppose C is scheduled to be created ten minutes after B. When B is created, B is identical to A. So A still exists. And A realizes that if C is created, A will cease to exist, because then there will be two people with psychology continuous with A's. If this is so, A's identity depends on whether C exists. But this is surely absurd. Who I am and whether I survive depends upon something about me, not about whether other people exist or will exist in the future.

I can think of a few objections to "brain persistence" views about person persistence, but if it ain't yet broke, I won't attempt to fix it. I would like to see objections to such a view, and defenses of psychological continuity views of personal identity. I realize I glossed the duplication problem with psychological continuity and the "unsatisfying" problem with non-reductionist views, so feel free to ask me to elaborate.

(I think what a "brain persistence" view suggests in the end about personal identity is that bodies constitute persons but are not identical to them, and the existence of a brain is the favorable circumstance that allows these bodies to constitute these persons. The two are spatially coincident but not identical.)

jpbrooks

Hello Thomas.

I tend to agree with you on this topic.
I found this interesting article on identity in The Philosophers' Magazine (TPM) website.

anonymousj

Just two quick questions, for the time being, the answers to which will, I hope, clarify your view for me.

1) Does your view mean that, if my brain is transplanted into Michael Jordan's brainless body, that new physical complex will be me. Or is it your view that I will persist as my brain, but only while my brain is in my body.
(I am formualting this in a way that might help me understand your last paragraph)

2) What is you view with respect to 'ship of Theseus' type questions? Suppose over a period of time, my brain is replaced piece by piece with human-made replacement parts (organic parts or non-organic parts or, ...) What will the consequences of your view be here?

anonymousj

Thomas Metcalf

Originally posted by anonymousj :

I think the person follows the brain. When the brain isn't in any body, then either the brain is constituting a person, or I think more plausible, no person exists until the brain is implanted. But if the brain has survived, the person has survived.

Good question. I'd say as long as the entire brain isn't replaced, you can still be around. Material objects get pieces taken out and replaced fairly commonly and we don't say they've ceased to exist. And I think if you're conscious during the above process, your entire brain will never be replaced, because you're constantly forming memories. Or, your brain will be replaced totally only if it happens all at once, in which case I'm willing to say you ceased to exist.

It's also a possibility that identity is indeterminate in a few cases when much of the brain but not all has been replaced.

mattbballman

tom,

This is certainly a definsible view that has been proposed by other philosophers. And it is consistent with a particular type of Christian theism as Christianity only requires that the eventual immortality of the individual require her physical body. As a result, various philosophical views have surfaced about mind/body dualism. But, per your article, many Christian philosophers accept this Thomistic theory that the body is part of what we call the "person" -- Descartes being an obvious objector. As famed philosopher Richard Swinburne says,

"Some dualists . . . seem sometimes to be
saying that the soul is the person; any living
body temporarily linked to the soul is no part
of the person. That, however, seems just false."
(R. Swinburne, "Dualism and Personal Identity",
from The Evolution of the Soul, rev. edn (Oxford:
Clarendon Press, 1997), p. 145).

On the other side of this debate are substance dualists who advocate mind-body dependence but suggest that the mind is the seat of the person. In this scenario, the person's survival is plausible. Such adherents include J.P. Moreland who himself says that,

"Regarding . . . scientific evidence for the
dependency [of the mind and body] . . . there
is also scientific evidence that mental states
causally effect brain states and, in any case,
substance dualist arguments, for example,
the modal argument and the argument from
libertarian freedom, seek to undermine its
justification."
(J.P. Moreland, "The Soul and Life Ever-
lasting", Philosophy of Religion, gen. ed.,
W.L. Craig (NJ: Rutgers U. Press, 2002),
p. 443).

Whatever one's opinion on the matter, both are consistent (Swinburne's and Moreland's in particular) with Christian eschatology.

matt