Dear colleagues,
The cumulative attraction of this online discussion, and now especially
Pedro's posting of 22 September, has hooked me. If you can forgive my late
intrusion, I would like to try out the following.
"The non-formal properties of information": here I believe Pedro is
bringing out something extremely important. I wish I could explain clearly
why I think this is crucial to the notion of natural computation, but I
need to work at it more. Here, though, are some very crude comments in that
direction.
Look at the idea of the imposition of form on substance. What does this
mean? Start with a piece of the world. Take, say, a ribosome in a living
cell. I mean a specific ribosome, this one, here, under this microscope
now. Individual. Particular. Not the type "ribosome." This sense of
"substance" I want to employ here. (The clumsy phrasing in this paragraph
is me trying to distinguish this from the Aristotelian notion of substance
as an object of logical predication.)
This ribosome has a function. Now it is a truism that "function" does not
inhere in physical objects, but arises from a network of relationships and,
perhaps, an interpretive community. We can, in a suitable frame of mind,
look at a thing and ignore its function. What are we looking at? That is,
take away function from the ribosome, and what is left? "Form". (The
answer seems irresistible.) Now take away form, then what is left?
"Substance" maybe? Is that really useful? At first, that sounds like some
residual meaningless metaphysical ooze-- ousia, in fact. Isn't all of
science about form anyway?
Anything on the level below form seems below scientific discourse, which
seeks out form. When we look at something as a scientist, we give it form.
It may even become a "system", with "states." In computer science,
representations of things are the object of study. We might represent an
agent, a transaction, or a number, for example. (One thing you tell
students in a computer science class is that it is meaningless to speak of
the complexity of testing if a number is a prime number; you must instead
speak of the complexity of testing whether a representation of a number is
a representation of a prime number. Some representations make it trivial;
some make it hard.)
But in _natural_ computation, things are different. Form, representation,
system, state-- in some way we must be able to occasionally bracket these
out and speak of substance alone. For example, an evolutionary exaptation
happens when one part of a biological substance, which served one function,
is recruited for another. The semantics is broken, and re-formed. There is
some discontinuity in how we can track change in substance by change in
formal representation. (I think the philosopher Hilary Putnam hit on one
part of this in his arguments against computational functionalism.) I
believe these "non-formal properties of information" are at the core of
the Conrad tradeoff between computability and amenability to evolution.
A separate observation: Pedro writes of looking at the thinker is his/her
"spare time, just when he/she is not acting in that peculiar 'scientific'
way." This evokes Wittgenstein (Philosophical Investigations 132 in
particular), where he points out that the confusions about language that
vex us do not occur when language is playing its real-life role (a
non-scientific, non-philosophical role-- in Pedro's scientist's "spare
time"). The confusions only occur in when language is taken off-line, as it
were, disconnected from its role in life, set on a rack ready to be
examined. [W's famous negative simile is that of language in this mode
being like "an engine idling". I just looked up the German text and there
is no "engine" mentioned directly: it's just "wenn die Sprache leerlau"ft."
Not being a native German speaker, I don't get the nuances, but the notion
of language "running on empty" seems engaging...]
The privileging of the real-life notion of information connects back to
some remarks by Hans several days ago, on the similarities between trying
to define information and trying to define energy. In fact, the art in a
beautiful loose definition such as (for example) "energy is the ability to
do work" is impressive. It is invariant across different sub-notions of
energy (Gibbs free energy, Helmholtz free energy…) and changing
understandings of fixed notions of energy (pre-relativistic vs.
relativistic, say). And its invocation of work hooks it in both to another
set of ordinary-life intuitions (I'm using "energy" pedaling this bicycle)
and to another physical concept (work) which can also admit further
mathematical elaboration. By so neatly injecting the concept into the web
of other physical concepts, it helps one do physics. (Ok- I am not a
physicist.) This is at least as valuable as a formal definition that gives
precise necessary and sufficient conditions for something to be called
"energy." Accordingly, I am a great appreciator of definitions of
information such as "reduction in uncertainty" or "difference that makes a
difference." They tie this plural concept into a scientifically useful
semantic web. If one wishes to charge into the still-dark territory of
"non-formal" information, it is definitions like these that will light the way.
Anyway, I apologize for the length of this posting, as well as its
still-fuzzy content.
-- Kevin
_________________
Kevin G. Kirby
Evan Stein Professor of Biocomputing
Department of Computer Science
Northern Kentucky University, Highland Heights KY 41099 USA
<mailto:kirby@nku.edu>kirby@nku.edu (859) 572-6544
Received on Mon Sep 26 16:52:53 2005
