P.O. Box 797
								Sonoita, AZ  85637-0797

								June 19, 2000

Prof. David Chalmers
Philosophy Department
Room 213, Social Sciences Building
University of Arizona
Tucson, AZ  85721-0027

Dear Prof. Chalmers:

	Well, here's another one from Mr. At-Least-I-Thought-Of-It-Independently. One of Roderick
Chisholm's favorite topics for public talks, as well as for his undergraduate metaphysics course, was identity.
He would compare two identical wooden ships built at the same time. One would simply be maintained, so
that as each plank wore out, it would be replaced with an identical wooden plank. On the other ship, when
each wooden plank wore out, it would be replaced with an iron sheet of equal area. After 30 years, the
second ship's wooden planks are all replaced with iron. There could be some debate whether the two ships
are now identical, depending on how you define "identical". However, if a human could be cloned in two,
and the cells of one replaced over 30 years, then you talk to both after 30 years, there would be no question
after 30 years they are the same person. They would have the same personality, mannerisms, speech style,
memories, and all the other things that characterize a personality.

	I heard Chisholm give that lecture freshman year at a public talk, and again senior year in my
metaphysics course. It got me thinking about a problem of little practical consequence to us, but perhaps of
critical importance to future generations. On the TV show Star Trek, there is a device called the matter transporter
used to transport objects and people from the starship to planets, other starships. etc. Since TV shows do not
come with manuals, I have no idea how this thing is supposed to work, but my guess is that it uses the Heisenberg
uncertainty principle. By reducing the measurement error of the momentum of each atom in an object to very near
zero, it increases the uncertainty in its position. If by somehow figuring out when the particles are located where
we want them, we stop measuring their momentum so well and collapse the error on their position. Of course this
last sentence makes no sense, but let's ignore that for a moment. Transporting inanimate objects poses no
problems, provided they arrive at the other end with all the properties they had when they left.

	Let's assume that consciousness requires an underlying physical basis, a (for the time being) biological
underpinning that mediates between the "external" physical world and our conscious experiences. When we
transport a body by conventional means, our unique consciousness travels with it. But how do we know that
when we step into a matter transporter that we will be the one that will step out the other end, and not some
clone that is really someone else who will take up our life where we left off and live it until they enter another
transporter? And what experiment could we perform to find out? Again, though this problem seems to be
hypothetical to us, it could be a matter of considerable practical concern to future generations.

	And while we are mulling over that one, here's another. One of the fundamental tenants of science is the
interchangeability of elementary parts. Every electron having the same quantum numbers as another electron
should be identical in every respect. So as a thought experiment, let's imagine that instead of having our matter
transporter actually move matter, what it moves is information. Let's borrow Larry Niven's jumpshift machine and
assume that the way it works is you enter this thing that looks like a phone booth, you close the door, you dial a
phone number, and you suddenly appear in another similarly configured phone booth. This thing works by scanning
your body, detecting the quantum numbers for every electron and baryon, transmitting that information to your
destination machine, then disassembling your body and putting the particles in storage for someone else coming into
this machine.

	In the meantime, in the destination machine, it has received the message with the information on the
particles in your body. It uses this information and particles from objects and people it has previously disassembled
to reconstruct you from this information. It has very carefully rebuilt you with every particle in its proper place, with
its proper quantum numbers. Now it did use different particles, but all particles are interchangeable. Did your
consciousness move? Would you be willing to trust your life to such a machine? Or would such a machine merely
clone someone with your personality but a different consciousness? What would Penrose say about these problems?

	Here's what my intuition tells me. I think that when we extend our theory of physics to explain consciousness,
as I stated in my first letter that we need to do, there will be more "quantum numbers" or some such description of
elementary particles, or there will be some property that sticks to a particle that makes it unique so that it is not
interchangeable with other particles of the same type with the same quantum numbers. That will make it necessary
to move the matter to move consciousness. That is, to move the person, you have to move the entire person and not
merely transmit information about that person. Maybe that's wrong, but I doubt I will live long enough to know. I
would be very interested in knowing the result.


								Mark Trueblood