Note: The following portions are necessarily incomplete fragments of
the referred papers, for a more complete understanding of the authors'
point of view I would refer those interested not only to the full papers
here partially quoted, but also to Pattee's and Kampis' respective, and
extensive, bodies of work.
Luis Rocha
Dept. of Systems Science and Industrial Engineering
T.J. Watson School of Engineering and Applied Science
State University of New York at Binghamton
Binghamton, NY-13902
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From: "Evolving Self-reference: Matter, Symbols, and Semantic
Closure" in CC-AI Vol. 12, Nos 1-2, pp 9-11. By Howard H. Pattee,
Systems Science Department, T. J. Watson School of Engineering,
State University of New York at Binghamton, Binghamton, NY
13901-6000.
1. What is self-reference?
Self-reference has many meanings. In symbol systems, like logic and
language, self-reference may lead to well-known ambiguities and
apparent paradoxes as in, "This sentence is false." In material systems,
like molecules and machines, self-reference is not clearly defined but
may describe causal loops such as autocatalytic cycles, feedback
controls, and oscillators. At the cognitive level, self-reference occurs
in introspection and is often considered one aspect of consciousness. I
define a specific form of self-reference that applies to a closure
relation between both the material and the symbolic aspects of or-
ganisms. I argue that this view of self-reference is necessary to under-
stand open-ended evolution, development, and learning at all levels of
organization from the origin of life to the cognitive level. This is not
an entirely new view, but is an elaboration and integration of ideas
from several well-established areas of physics, logic, computation
theory, molecular biology, and evolution theory. To state my position
as briefly as possible, self-reference that has open-ended evolutionary
potential is an autonomous closure between the dynamics (physical
laws) of the material aspects and the constraints (syntactic rules) of the
symbolic aspects of a physical organization. I have called this
self-referent relation semantic closure (Pattee, 1982) because only by
virtue of the freely selected symbolic aspects of matter do the
law-determined physical aspects of matter become functional (i.e., have
survival value, goals, significance, meaning, self-awareness, etc.).
Semantic closure requires complementary models of the material and
symbolic aspects of the organism. This brief statement requires much
more elaboration.
I have emphasized in many papers (e.g., Pattee, 1969, 1972, 1982) that
the matter-symbol distinction is not only an objective basis for
defining life but a necessity condition for open-ended evolution. My
reasoning is based not only on biological facts but on the principled
epistemic requirements of physical theory. In other words, I require
that models of living systems must be epistemologically consistent with
physical and logical principles. It is well known that replication and
evolution depend crucially on how the material behavior of the
organism is influenced by symbolic memory. Biologists call this
matter-symbol distinction the phenotype and genotype. Com-
putationalists call this the hardware-software distinction. Philosophers
elevate this distinction to the brain-mind problem. What is not as well
known is that even in the formulation of physical theories a form of
matter-symbol distinction is necessary to separate laws and initial
conditions. I will explain this further in Sec. 4.
The logical necessity of this matter-symbol complementarity was first
recognized by von Neumann (1966) in his discussion of self-replica-
ting automata that are capable of creating more and more complicated
automata. This is often called emergent evolution. Von Neumann
noted that in normal usages matter and symbol are categorically
distinct, i.e., neurons generate pulses, but the pulses are not in the
same category as neurons; computers generate bits, but bits are not in
the same category as computers, measuring devices produce numbers,
but numbers are not in the same category as devices, etc. He pointed
out that normally the hardware machine designed to output symbols
cannot construct another machine, and that a machine designed to con-
struct hardware cannot output a symbol. This was a simple observation
about actual machines and the use of natural language, not an
ontological or dualistic assertion. Von Neumann also observed that
there is a "completely decisive property of complexity," a threshold
below which organizations degenerate and above which open-ended
complication or emergent evolution is possible. Using a loose analogy
with universal computation, he proposed that to reach this threshold
requires a universal construction machine that can output any
particular material machine according to a symbolic description of the
machine. Self-replication would then be logically possible if the
universal constructor is provided with its own description as well as
means of copying and transmitting this description to the newly
constructed machine.
As in the case of the universal computing machine, to avoid the am-
biguities of self-reference, logic requires the categorical distinction
between a machine and a description of a machine. This logic does not
differ if the machine is a material machine or only a formal machine.
To avoid self-reference requires two logical types or categories. This
is the logical basis of the symbol-matter distinction. It is significant
that his so-called kinetic model required primitive parts with both
symbolic functions (i.e., logic functions, ) and material functions (e.g.,
cutting, moving, etc.). I will discuss this argument in Sec. 9. Von
Neumann made no suggestion as to how these symbolic and material
functions could have originated. He felt, "That they should occur in
the world at all is a miracle of the first magnitude." This is the origin
of life problem.
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