Biology Reference
In-Depth Information
There are a couple of features of both Rosen's and Varela's account that
merit comment. First, both of them dissociate the organizational features that are
crucial for living systems from their material realization. Varela, for example,
comments:
We are thus saying that what defines a machine organization is relations, and
hence that the organization of a machine has no connection with materiality, that
is, with the properties of the components that define them as physical entities. In
the organization of a machine, materiality is implied but does not enter per se .
(p. 9)
In making this dissociation, both Varela and Rosen endorse the sort of multiple
realizability argument that has figured so strongly in functionalist theories of
mind and has led numerous philosophers of mind to downplay the significance
of the brain to the understanding of cognition. The plausibility of multiple real-
izability claims, however, often results from adopting overly simplistic accounts
of functional organization and from focusing on abstract accounts of machines,
such as the Turing machine. In real machines, the relations in which a compo-
nent can stand are significantly limited by the material out of which they are
constituted - change the material, and there will be detectable changes in func-
tionality. When one takes the organizational demands on complex systems very
seriously, it is far from clear that there are multiple material realizations that
could produce the same functionality (Bechtel & Mundale, 1999). 26 A second,
and related point, is that neither focuses on the energy requirements of the
systems they consider. In this regard, it is interesting to focus on the fact that
the first component that Rosen added to his metabolic operation was a repair
operation. Indeed, repair is a crucial feature of living systems, but the reason it
is so important is that biological systems, as highly organized systems, exist far
from thermodynamic equilibrium. As such, they will dissipate, and in so far as
they are chemical, not solid systems, such dissipation will be relatively rapid. 27
26 A second consideration that leads other theoreticians to attempt a materially independent characterization
of living systems is found in the artificial-life community which seeks to understand life in its full generality
and not to be 'earth chauvinists'. Seeking universal categories, however, is not the only way of avoiding earth
chauvinism. A different strategy is to begin with the concrete case we know - life on earth - and to branch out
from it by considering variations that are possible. This fits the common strategy in biology of starting with
a model system (e.g., the giant squid axon), develop an account of the mechanisms operative in it, and then
investigate the similarities and differences found in other related species. One reason this is likely to succeed
often on earth is the conservation of mechanisms that results from natural selection, which of course will
not apply to nonearth-based life. Nonetheless, the strategy of starting with mechanisms we know to function
successfully on earth and then considering variations is far more likely to succeed than a strategy of seeking
generality by discounting what we know of earth-based mechanisms. The latter is a strategy that may only
result in vacuous generalities.
27 It is perhaps because of the problem of dissipation that humanly engineered machines have historically been
made of solid, rigid components. Although such machines do experience 'wear and tear' and so need repair,
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