X-Message-Number: 9243
From: Thomas Donaldson <>
Subject: Re: CryoNet #9238 - #9239
Date: Wed, 4 Mar 1998 23:56:43 -0800 (PST)

Hi everyone!

Well, Mike! What is this digital business and why is it important? I even 
gave you a reference to a paper in which a machine was described which was
PROVABLY not a Turing machine (a neural net with incommensurable lengths of
message-paths between nodes). What did you think of it? You must have
reasons to brush off something like that so easily.

Moreover, in what way is being digital important to understanding how we
work? Sure, we need to know how we work on lots of levels. But just what 
do we gain by assuming that on one of these we may be "digital" --- which
seems to me to be (simply put) the notion that a good model for how we
work on that level would basically have us working always in integers, 
like a complex collection of cubic blocks on a 3 dimensional surface.

Yes, it is useful to model some things in computers, and computers are
digital. But our models are models, not the real thing. And if the 
connections between our neurons are incommensurable, then we probably 
can't be modelled by Turing machines. This is not a disaster, it simply
says we have to use other models. It does not require much ingenuity to
provide such models.

As you may remember me saying on other occasions, I have no problem with 
the idea that we may somehow and someday construct a "brain" capable of
the same kind of thinking that we do and the same kind of perceiving, too.
But I think we are on very shaky ground if we blithely assume that 
this "brain" will be a digital computer of any kind. I will make that 
a much stronger statement: a very good way to misunderstand completely
how humans or other animals work is to assume that their brains act like
computers. Sure, some parts of our brains can be modeled with computer
models, but the model is not the thing.

I look forward to your answer.

			Best and long long life to everyone,

				Thomas Donaldson

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