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supramolecular chemistry and self-assembly, and having the ability to adapt
and evolve by means of near-perfect replication and natural selection.
The abstract diagram in Fig. 8 can be extended to one that matches Fig. 9. This
abstract representation of the self-fabricating metabolism-construction-assembly
(M, C, A) organisation of living cells is given in Fig. 10. I propose this as
an alternative to the replicative (M, R)-systems described by Rosen. Both are
closed to efficient causation, but the (M, C, A) description has a number of
distinct advantages. First, it maps onto the known biochemistry of the cell,
whereas neither Rosen nor anybody else has been able to map the replication
aspect of (M, R)-systems (which closes these systems to efficient causation)
onto biochemical processes. In the language of category theory the replication
component of (M, R)-systems is equivalent to an inverse evaluation map, and
nobody seems to have been able to interpret this in terms of a physical process
or object. The second advantage is that the (M, C, A) organisation reconciles
Rosen's and Von Neumann's treatments. As mentioned in Section 2, Rosen's
recasting of the Von Neumann architecture led to a logical paradox which has
since apparently served to isolate these two views from each other (Rosen,
1959a, 1962). In a separate paper we shall show how to formally avoid this
Rosen-Von Neumann paradox by using the formulation in Eqn. (4) instead of
Eqn. (3). A third advantage is that the unassisted self-assembly component of
(M, C, A)-systems obviates the need to postulate an agent that directly fabricates
itself, a notion that I still find problematical. A fourth advantage is that the (M,
C, A) architecture matches the triadic relationship between genotype, phenotype
and ribotype suggested by Barbieri (1981, 2003) (see Fig. 11). Barbieri suggested
A
f
r
s
B
C
D = { r , f , g }
x
I
g
I 0
Figure 10 Adding self-assembly and information processing to the metabolism-
construction system in Fig. 8.
Here the fabricator r cannot make itself directly, but it can make all its own components and
of course those of all the other machines; together they form set C. These machine components
then self-assemble spontaneously through mapping s to form the set D, which then contains the
constructor r and all other machines. This factory also makes a set of information processors
g that translate archival information I 0 into blueprints I.
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