"congruence via encoding"

[Howard Pattee <***>]

At 09:09 AM 12/29/04 -0500, Tim wrote:
> Howard,
>  It seems to come down to a difference in what we each consider "commute" 
> to mean, or the requirements for a modelling relation to "commute". For 
> me, I take Rosen's stance that it involves bringing the entailment 
> structures into congruence via the encoding/decoding. [snip] Can you 
> explain what you mean by the "commutation condition" on a modelling 
> relation - what kind of requirement does this place on the modelling relation?

HP: I also accept Rosen's stance, but I see it as entirely consistent with 
Hertz who could have said, "the logically necessary consequents [formal 
model entailments] of the images [the encodings] are [congruent with] the 
images [encodings] of the necessary natural consequents [causal 
entailments] of the thing pictured [modeled].

Rosen's essential concept here is "congruence via encoding" (measurement), 
and in my opinion these concepts cannot, and should not, be precisely 
defined except for each specific model. For example, congruence may mean 
high numerical precision as in celestial positions or atomic spectral 
wavelengths, but it also may mean visual images with similar patterns, 
structures, or symmetries, or it may mean functional equivalence as in 
dynamical analogs. If you look at the actual encodings of physics 
experiments you will see that the variety is enormous, and there is no 
argument I know that would proscribe the processes of encoding or meanings 
of congruence.

Rosen often points out that encodings or measurements must be entirely 
different for different models. The meaning of congruence must also be 
different. Or more precisely, what we define as the system being modeled 
and what we call the state of the system is actually determined by what 
observables we choose to measure. What observables we choose and what we 
mean by congruence is in turn determined entirely by what questions about 
the system we want to answer.

It seems to me that in Life Itself Rosen does not recognize that physicists 
should seek entirely different answers than should biologists. The basic 
question physicists want to answer is clearly not the same as the questions 
biologists want to answer, and therefore the observables, states, and 
congruences chosen by physicists should not be the same as the observables, 
states, and congruences chosen by biologists. Physicists are looking for 
those Natural Laws that are universal and inexorable. Universal means 
ideally that the laws apply to all systems independent of the state of any 
conceivable observer. Inexorable means ideally that nothing can alter or 
control these laws. We feel that Natural Laws could not be other than what 
they are. Physicists agree that this is an ideal that has only been 
approximated by their models, but they keep getting better models.

The cost of finding this uncontrollable universality is that the basic 
observables and state variables of physical systems must be kept simple and 
few in number, like mass, length, time, charge, spin, etc. Of course as 
more complex systems are modeled more observables are necessary, like 
valance, chemical potentials, temperature, pressure, and entropy, etc., but 
these models are to answer more specific questions and therefore they are 
often less universal.

Biologists, on the contrary, are looking primarily for models of control 
which is what organism do to stay alive and replicate. Biologists accept 
Natural Laws but see the organism as a network of control constraints 
beginning at the molecular level with sequence control by genes, rate 
control by enzymes, messenger control of metabolism, and continuing 
hierarchically through many levels. At the highest level the brain controls 
the overall behavior of the organism. Rosen and I early in our work argued 
that every level of the biological hierarchy asks different questions and 
therefore requires different observables, states, and models. Rosen devotes 
an entire chapter to these different biological encodings in Anticipatory 
Systems (3.4 and 3.5).

In other words, I find that I am in agreement with Rosen's ideas as 
expressed in Anticipatory Systems where he appreciates the different 
questions physics and biology ask, but am not able to understand or agree 
with his different attitude towards physics and biology in Life Itself 
where he seems to be saying that they both are asking the wrong questions.

Does anyone else see this difference between these two books?

Howard