FISers,
Jerry Chandler has said of me:
"As I read your post, you seem to be involved with an internal debate
with yourself."
Stan, too, has patiently persuaded me toward accepting a hierarchical
infostructure in living systems.
I am now more inclined to agree with them. I seem to be operating in
a closet on this issue of "biological hierarchy." I have been
opposed to it for one simplistic reason�"downward causation." This,
to me, in my naive way of fumbling with the concept, has suspiciously
spiritual implications. But then today I am gratefully blind-sided
and humbled by John Collier's post (below) that introduces far much
more fresh thinking on these matters of hierarchy and downward
causation than I had ever imagined. So I have downloaded many of
John's papers on these subjects, noticing that Stan Salthe is cited
in them. I need to read more of his stuff, too. (These guys are
heavyweights and I'm Peewee Herman!) I intend to become educated in
this field that I really know nothing about. After that I may have
something more relevant and useful to say about hierarchy and
biological evolution. There seems to be more emergent properties in
biological systems than I previously recognized. Time to read more
and say less.
Best regards, Richard
On Nov 22, 2006, at 5:10 AM, Pedro Marijuan wrote:
> Dear John and colleagues,
>
> As usual I am having too short a time (will attempt to answer
> properly next week, also to James and Jerry), but your reflections
> connecting with mechanics and computability have initially reminded
> me a rather obscure paper by Michel Conrad and Efim Liberman, where
> they discuss in a philosophical annex the nature of physical law in
> connection with the Church-Turing principle of computability. I
> could never make complete sense of their speculations (quite deep
> ones)... it is the same type of reasoning you are making:
> peripherally relevant as you say. I will try to quote from Michael
> and Efim next week
>
> Thanks for the stuff.
>
> Pedro
>
>
> At 20:10 17/11/2006, you wrote:
>> Dear colleagues,
>>
>> Pedro has pointed out a real problem, I think. I have a few words
>> to say
>> on it that may be of some help in sorting out the issues. They derive
>> partly from my trying to make sense of Atlan's use of computational
>> language along with his claim that some biological (biochemical
>> really)
>> stuctures have "inifinite sophistication". A structure with
infinite
>> sophistication cannot be computed from the properties of its
>> components. Sophistication, as far as I can tell, is a measure of
>> computational depth, which depends on the minimal number of
>> computational steps to produce the surface structure from the
>> maximally
>> compressed form (Charles Bennett). Atlan has made the connection, but
>> also noted it is not fully clear as yet, since Bennett's measure is
>> purely in terms of computational steps, and is relative to maximal
>> compression, not components. Cliff Hooker and I noted these problems
>> (before we knew of Atlan's work -- well, I did, but it was presented
>> poorly by one of his students -- see Complexly Organized Dynamical
>> Systems, Open Systems and Information Dynamics, 6 (1999): 241-302.
>> You
>> can find it at
>> http://www.newcastle.edu.au/centre/casrg/publications/Cods.pdf).
The
>> question relevant to Pedro's post is why is computation relevant if
>> common biological systems have infinite sophistication, and thus
>> are not
>> effectively computable, even if they have finite complexity?
>>
>> Here is my stab at an answer: the notion of mechanical since
>> Goedel and
>> Turing (I would say since Lowenheim-Skolem, since Turing's and
>> Goedel's
>> results are implicit in their theorems) breaks up into to notions,
>> stepwise mechanical and globally mechanical. A globally mechanical
>> system can be represented by an algorithm that halts on all relevant
>> inputs (Knuth algorithm); these are computable globally. The stepwise
>> ones have no global solution that is effectively computable, but are
>> computable locally (to an arbitrarily high degree of accuracy). The
>> difference is similar to that between a Turing machine that halts
>> on all
>> relevant inputs and one that does not. Both are machines, but only
>> the
>> latter corresponds to Rosen's restricted notion of mechanical. So
>> computation theory can help us to understand the difference between
>> things that are stepwise mechanical, and things that are not.
>> Things of
>> infinite sophistication are not globally mechanical. I will say
>> without
>> proving that they correspond to Rosen's systems that have analytical
>> models but no synthetic models. They may still be mechanical in the
>> weaker sense. In fact I have not been able to see how they cannot be
>> mechanical in this way.
>>
>> Consequently, there are Turing machines that are mathematically
>> equivalent to systems of infinite sophistication, but they do not
>> halt.
>>
>> So you are probably wondering how processes of this sort can occur in
>> finite time. The answer is dissipation. I'll not give the solution
>> here,
>> as my coauthor on another paper just came into the room and asked
>> me how
>> it was going, and I said I was writing something else that was
>> peripherally relevant :-) A case in point is given in my
>> commentary on
>> Ross and Spurrett in Behavioral and Brain Sciences titled Reduction,
>> Supervenience, and Physical Emergence, BBS, 27:5, pp 629-630. It is
>> available at
>> http://www.nu.ac.za/undphil/collier/papers/Commentary%20on%20Don%
>> 20Ross.htm
>> as well as the BBS site.
>>
>> All spontaneously self-organizing systems (see the Collier and Hooker
>> CODS piece) are only locally mechanical. I won't prove that here, but
>> there is a clue in the BBS commentary.
>>
>> Cheers,
>>
>> John
>>
>>
>> Professor John Collier
>> Philosophy, University of KwaZulu-Natal
>> Durban 4041 South Africa
>> T: +27 (31) 260 3248 / 260 2292
>> F: +27 (31) 260 3031
>> email: collierj@ukzn.ac.za
>> http://ukzn.ac.za/undphil/collier
>
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Received on Wed Nov 22 19:18:57 2006
