X-Message-Number: 9267
From: Thomas Donaldson <>
Subject: Re: CryoNet #9260 - #9261
Date: Thu, 12 Mar 1998 01:30:19 -0800 (PST)

Hi Mike!

Hey! I hope you read my message in THIS Cryonet, and will put up the reference
I gave you. Then we can really have a discussion. As I said, I've got the
original reference packed away by now.

Sorry, but the implied idea that if I don't believe we are finite Turing 
machines I must therefore believe that we run by supernatural means just 
doesn't ring any bells with me. If finite nonTuring machines can exist, then
that is sufficient.

Just what would be wrong, metaphysically, if the Church-Turing thesis failed?
You should understand that PCs and Crays will go on working just as before,
and people will still write programs, and still think about AI. (In fact,
a counterexample may mean more for AI than for any other computer 
discipline).

If by digital, you simply mean that our own experiences are discrete and
finite, I will freely admit some kind of finitude, but discreteness is
going to (at least) require more argument. Consider vision, and our memory
of scenes: we don't obviously see things discretely, we see them as 
continuous. Yes, a sufficiently good monitor (better than any yet made)
could produce a discrete image so fine that we could not tell the difference
between it and looking through a window at a real scene, but that only tells
us that our vision can be fooled, not that it is discrete. (I don't claim
this is a complete argument, but it does raise problems in my mind with 
the notion that our experiences are discrete).

Or again, since we have a finite number of neurons then you may simply
say that a particular event produces a discrete set of states of our
neurons. But neurons are not digital, if anything they are analog. Nor can
we argue simply that the molecules in our neurons will take on a discrete
set of states --- space is at least apparently continuous, and an enzyme
can rotate (among other things). Even though nerve transmitters are 
released in small packets approximately the same in content, each packet
is part of a larger pattern of release, and does very little if released
alone.

Yes, this could go on and on, but I won't do that. But even though 
our experience is not obviously discrete, even if it were you'd have to
go further to argue that it was digital in the sense that computers are
digital. For our experience may be discrete, but the individual "atomic
events" which make it up need not be commensurable, so that we could not
analyze it as made up of different multiples of some common basic "atomic
experience". Though atoms are discrete, energy levels need not be
commensurable, nor need their positions be commensurable. After all,
photons come with many different energies.

Yes, there is more to be said on both sides. But it's getting late and
I've had a long day. I'll leave this discussion by pointing out that
as yet, general relativity and quantum mechanics remain unreconciled.
So think a bit: there must be some wider theory that includes the 
phenomena explained by each of them, though it may disagree experimentally
with both. If we base our ideas of human survival upon either or both,
we may awaken from our suspension to find both theories, and all the 
philosophies built upon them, to be history only, and dismissed by the
people of that time as we now dismiss phlogiston. And I would not be
surprised if the Church-Turing thesis, too, had become a forgotten
byway which had finally failed to deal with all the devices and 
phenomena we will learn to create.

		Best wishes, and long long life,

			Thomas Donaldson

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