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From: cohenb@slc.com (Bruce Cohen)
Subject: Re: What's going on?
In-Reply-To: A.R.Diller@cs.bham.ac.uk's message of 3 Jul 1995 12:47:58 GMT
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Organization: GemStone Systems, Inc.
References: <3r6klu$jnk@seralph9.essex.ac.uk> <agapow.803362346@latcs1.lat.oz.au>
	<3s1nkf$3eg@decaxp.harvard.edu> <agapow.804132037@latcs1.lat.oz.au>
	<3t8otu$5k0@percy.cs.bham.ac.uk>
Date: 04 Jul 1995 18:45:52 GMT

In article <3t8otu$5k0@percy.cs.bham.ac.uk> A.R.Diller@cs.bham.ac.uk
(Antoni Diller) writes:

>> In article <agapow.804132037@latcs1.lat.oz.au>, p-m agapow
>> <agapow@latcs1.lat.oz.au> wrote:
>> 
>> >Emergence is behaviour on one level that cannot >be anticipated or
>> reduced to behaviour on a lower level.
>> 
>> It's not just that; there's also the phenomenon known as `downwards
>> causality' (by Donald Campbell in the 1960s and 1970s), ie, the
>> objects at a higher level can causally affect objects at a lower
>> level. Eg, if the mind is an emergent entity, then what is important
>> is whether or not it can causally affect, say, the behaviour of brain
>> cells and neurons---out of which it is ``made''.  I think that
>> downwards causality is what is really important in anti-reductionism.

I agree.  I believe you can take this idea of downwards causality a bit
further.

If you think about the structural organization of systems, it seems a
reasonable conjecture that the hallmark of complex, adaptive,
self-organized systems (perhaps autopoietic systems as well, though I
expect that's somewhat controversial) is that its structure is a
heterarchy rather than a strict bottom-up or top-down hierarchy.  In a
heterarchy (I've heard them called "tangled hierarchies" and the name
seems apt). causality usually goes both up and down.

A classic, and well-studied, example of heterarchy is the human visual
system, in which inputs to the retina stimulate nerve impulses (I'm
tempted to say "output data flow", but that gets into arguments about
computational models I'm not concerned with here) to go to low-level
processing systems (edge detectors and whatnot) and the outputs from
them go to higher-level processors.  At the higher levels there are
feedbacks which go back down to the lower levels to modulate their
sensitivity to characteristics of their inputs.  You can follow this all
the way up to conscious processes and bac down through motor control of
the head and neck to control where the retinas point
-- 
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"Only a proper understanding of the constraints imposed by the
properties of our space and of the rich repertoire permitted within
these constraints allow the achievement of a balanced disciplined
freedom."  - Arthur Loeb in "Concepts and Images"
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Bruce Cohen, GemStone Systems, Inc.              |   email:  cohenb@slc.com
15400 NW Greenbrier Pkwy, Suite 280              |   phone: (503)690-3602
Beaverton, OR USA 97006                          |   fax: (503)629-8556
