X-Message-Number: 14729 Date: Wed, 18 Oct 2000 20:25:31 -0400 From: Thomas Donaldson <> Subject: more about brains and computers A reply to the various people who don't like even the SUGGESTION that our brains aren't computers: First, as I said before, I was making a suggestion not proposing a thesis. But I should still explain it a bit more, it seems. In terms of the issues raised, I will say first that I'd like a bit better definition of just what an "information processor" is, and what is "information". There is a subtlety here: any symbolic statement of the state of ANY machine, no matter what it does, constitutes information. That's clear. But is the actual state of the machine an expression of information? I am saying that it is not. The ability to set up symbols which EXPRESS the state of the machine is fine and useful, but those symbols remain a symbolic expression only. Moreover, even an ordinary computer tied in with some kind of sensory system and some kind of action system will basically use a symbolic system to express the state of its perception. Doing so isn't necessary and may turn out to be inefficient. Sure, with lots more power than our brain such a system might work just as well, but a lot of that power is spent on doing something which brains do by not acting symbolically. Finally, I will point out that no machine yet has the ability to constantly rewire itself in the way brains do. It's easy to see how to make such a brain if we assume only a small number of nerve cells: just set it up with all possible connections and then turn off some of those connections. But even the most primitive mammal has enough brain neurons that such a proposal becomes impossible in practice, even if it remains possible in theory. So more effort is needed. AS I said in my original message, we may yet build such a machine; whether it qualifies as a Turing machine is a question which needs answering, not one which is obvious. Is the world itself a Turing machine? I would say it is not. Best wishes and long long life to all, Thomas Donaldson Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=14729