Reacting first to Bill, then to Loet, then to Bob
Concerning Bill Hall's posting, I note that Popper's three worlds can
be neatly repreented in the specification hierarchy format:
{World 1 {World 2 {World 3}}}
vis
{physico-chemical dynamics {biological processes {sociopolitical projects}}}
That is, each higher world depends upon the lower ones, and in turn
integrates them locally.
----------------------------
Replying to Loet -
> S: The material reason that Shannon information cannot be used to
calculate information carrying capacity in biology (or for any
dissipative structures), is that there is no way way to find the
complete repertoire of any such system. Thus, it is not
technologically 'useful'. However, it does carry conceptual weight
nevertheless. It can be used to roughly assess relative
configurations. Thus, a tornado has more possible macroscopic
conformations than does a bird, and this has more than a snail.
In my opinion, Stan, this is confusing. For the computation of the
Shannon-type information one only needs the number of categories at specific
moments of time (log(N)). Both the maximum entropy and the observed
complexity can be expected to change over time (Brooks & Wiley, 1986). Of
course, one cannot specify all possible repertoires in the future, but in
anticipatory systems the possible repertoires at each moment can again be
specified, in principle.
Thus, we may hold to information theory. This is desirable for reasons of
parsimony and because there is no alternative. As I have argued before, the
organization of the Shannon-type information can be modeled by allowing for
a second degree of freedom in the probability distribution, or in other
words to distinguish an organizing variable versus an organized uncertainty.
In addition to the Shannon-type information, one can then also most easily
compute the mutual information as a representation of the organizational
(and historical!) constraints.
S: My reply is that the difficulty (?impossibility) of
quantitatively estimating the maximum entropy of a natural system
does not derive from our inability to foresee its future states, but
from an inability to categorize its many present possible states.
Consider the human body. How may conformations shall we say that it
could assume in the next moment? Of course, if we are attempting
this from some narrowly pragmatic project, we could impose, say,
three categories of conformations relative to the problem at hand and
sample only for these, thus eliminating an unknown number of
conformations of no interest. Perhaps I am too 'philosophical, but
it seems to me that the 'entropy' concept is no longer of much
interest here.
-----------------------------------
Bob said -
Hi Stan - thanks for commenting on my post. I really liked your
remark highlighted in pink. But I have a problem understanding the
remarks in blue. Perhaps you could clarify for me. Why is it also
true for any dissipative system and what exactly do you mean by a
dissipative system? Also I do not see how Shannon info can be used
to roughly assess relative configurations. Also why does a tornado
have more possible macroscopic conformations than does a bird, and
this has more than a snail. Finally. what is a conformation?
These questions are not posed to challenge your assertions but
rather to help me understand them.
S: Of course. OK. I use 'dissipative structure' in the
Prigoginian sense. I use 'conformation' as in molecular biology, as
one form that may be assumed by a material object of a given
configuration - one configuration, many conformations. I would
imagine using Shannon info to assess how many conformations a
configuration might assume, and that could work for, say, a protein
in a given environment.
My general point here is that physically (thermodynamically), living
systems are not different from other dissipative structures except in
their complication (?complexity). As I see it, living systems are
just more highly specified dissipative structures, based on their
internal information storage. Indeed, leaving aside the uncanny
origin of the genetic system, the living must have been launched
upon, or took over by information import, some prior dissipative
structure(s). Now, considering that this event produced a more
definite kind of system, it is clear that the Shannon information
capacity really first appeared then in Nature as a possible inquiry,
inasmuch as abiotic dissipative structures are so vaguely embodied
(think tornado) that the category of informational entropy can hardly
be applied to them. So, in fact, I was in error to state that one
might assess how many conformations a tornado might assume. It is
too vague for such a measure.
STAN
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