[NetBehaviour] Free Will and Identity.
marc.garrett at furtherfield.org
Wed Nov 7 02:10:41 CET 2007
Free Will and Identity.
Identity: who am I?
Every year 98% of the atoms of my body are replaced: how can I claim to
be still the same person that I was last year, or, worse, ten years ago?
What is (where lies) my identity? What is "my" relationship to the
metabolism of my body?
Derek Parfit once proposed a thought problem: what happens to a person
who is destroyed by a scanner in London and rebuilt cell by cell in New
York by a replicator that has received infinitely detailed information
from the scanner about the state of each single cell, including all of
the person's memories? Is the person still the same person? Or did the
person die in London? What makes a person such a person: bodily or
psychological continuity? If a person's matter is replaced cell by cell
with equivalent cells is the person still the same person? If a person's
psychological state (memory, beliefs, emotions and everything) is
replaced with an equivalent psychological state is the person still the
same person? The question eventually asks what is "a life": is it a
continuum of bodily states, whereby one grows from a child to an adult,
or is it a continuum of psychological states? Or both? Or none?
The most obvious paradox is: how can reality be still the same as we
grow up? Do two completely different brains see the same image when they
are presented with the same object? If the brains are different, then
the pattern of neural excitement created by seeing that object will be
completely different in the two brains. How can two completely different
brains yield the same image in the two brains? The logical conclusion is
"no, the tree I see is not the tree you see, we just happen to refer to
it the same way so it is not important what exactly we see when we look
at it". But then how can we see the same image yesterday, today and
tomorrow? Our brain changes all the time. Between my brain of when I was
five years old and my brain of today there is probably nothing in
common: every single cell has changed, connections have changed, the
physical shape of the brain has changed. The same object causes a
different pattern in my brain today than it did in my brain forty years
ago. Those are two different brains, made of different cells, organized
in different ways: the two patterns are physically different.
Nonetheless, it appears to me that my toys still look the same. But they
shouldn't: since my brain changed, and the pattern they generate has
changed, what I see today should be a different image than the one I saw
as a five-year old. How is it that I see the same thing even if I have a
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