From: erlebach@Informatik.TU-Muenchen.DE (Thomas Erlebach)
Subject: Simulated Brain
Originator: erlebach@hphalle3a.informatik.tu-muenchen.de
Organization: Technische Universitaet Muenchen, Germany
Date: Tue, 29 Sep 1992 15:18:01 GMT


In the first part of this text I will explain what I think about
the human brain, the second part will contain some questions that
come to my mind when I think about this subject. I haven't read
much about the philosophical perspective of this topic, so I hope
that some of you find my thoughts interesting, although I am afraid
that much of it might have been thoroughly discussed already.
(I am just about to begin reading this newsgroup.)

After reading some articles and books on psychology and on the anatomy
of brains I have come to the conclusion that the human brain is nothing
but a very complicated, highly developped machine.
Adding to that, I don't think that there is a soul or something that
resides in my body and that could live on when I die. In other words,
I am not in favour of the theory of dualism of mind and brain.

Arguments to support my opinion:
- In a human brain there are regions which perform tasks like
  memorizing things, understanding language or recognizing faces.
  People who suffered damages to parts of their brains often lack
  just one of these abilities while everything else still works.
  There have been cases when patients lost the ability to have
  emotions after having certain brain surgery done, others had
  a quite different character after such an operation (I speak
  of operations that were done quite a time ago in hopeless
  cases like heavy epilepsy).
  If all these human qualities are capabilities of our physical
  brain, why should there be a non-physical entity like a soul ?
  As most people think a soul would live on after the physical
  death, and it would have the character and the memory of the
  person it was. If the soul has a memory itself, why should the
  physical brain have a memory on its own ?
- Examination of the anatomy of brains has revealed a lot of
  neurons with a very high number of connections between them.
  Although we don't understand too much about the way a brain
  recognizes faces (for example), we have quite a good impression
  on how a neuron works: it gets input (electric pulses) from
  other neurons, and if the input matches certain conditions (if
  the sum of all inputs is above a certain value ?) a neuron
  sends electric pulses to other neurons it is connected with.
  This is basically the same in insects, fish or humans, only
  the grade of connectivity and the structure differ. There is
  nothing magic in brains, they are just complicated biological
  machines.

Conclusion:
  Since a brain is a kind of machine, it is possible to simulate
  a brain on a computer. All you need is:
      1. complete understanding of the way a brain works
      2. a computer fast enough and with enough memory to simulate
         that brain
  Of course both of them are not available now, but I don't think
  there is any reason why it should be impossible to have them in
  the future. Anyway, this is just a thought experiment for now.
  With computer I mean something like a super-PC: just one CPU and
  memory and I/O-stuff, no fancy new brain-like architecture, only
  a hyper-fast version of an 80486 CPU and a hyper-large memory.
  All you have to do is: Get a model of the brain into the computer
  (which will be rather difficult, too, but not impossible I think)
  and write a program that simulates that brain. You can add various
  input/output devices, but the details are not important here.
  To make it simple let us assume you can talk with that simulated
  brain (it gets your voice as input and speaks to you).

Questions arising:
------------------
1. Does the simulated brain have the same capabilities, qualities,
   thoughts and feelings as a biological brain ? From reasonable
   thinking I come to the answer: yes, although I'm having great
   difficulties imagining that.
2. We consider it a very bad thing to murder a human being. How
   about turning off the computer that simulates a brain and
   destroying the disk on which the model of the brain is stored ?
   Isn't that the same as murdering your neighbour ?
   Again I think the answer is: yes, but again it is hard for me
   to think of turning off a machine as murder.
3. Somebody dies and you examine his brain until you can get a model
   of it into the computer. Then you start the simulation and talk
   to the dead (?) person. He tells you about the feelings he had
   when he died. Is this a possible scenario ?
4. Suppose I could get a model of my brain into the computer
   without destroying it (my brain). When I start the simulation,
   I exist two times: biologically and in the computer. What do
   you think about that ?


Thank you for reading this text. If you have any answers, thoughts,
comments, criticism or whatever about this article, I would be glad
if you posted them or sent them to me in e-mail. I am really curious
what you think about this.

                                  Thomas Erlebach


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- erlebach@informatik.tu-muenchen.de                                  -
- "A fanatic does what he thinks the Lord would do if He knew the     -
- facts of the case."                - Finley Peter Dunne             -
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