Tim writes:

>Certainly I share many of Wolfram's intuitions about not even the
>billions of years available being enough for natural selection to
>be able to "design" very much in the way of complex systems - and
>since self-organising systems - of the type that can arise from
>short and simple developmental programs - generate ordered complex 
>structures in great abundance, they are a natural explanation for
>much of the observed complexity in nature.

There's a certain level of nonsense in these few sentences. As someone whose
work is occasionally mentioned in the same breath as Wolfram's (especially if
you breathe in Russian:

     http://www.computerra.ru/offline/1999/289/2524/ ),

let me say rather unequivocably that the bottom-up analyses characteristic of
Wolfram are almost always in error. When you begin from the component level,
you invariably end up with "over-wise" genes, cells, neurons, resistors or
transistors, depending only on the form of system that is under discussion.

Two approaches to the analysis of complex informational structures are
possible: either from the bottom-up or from the top-down. Bottom-up analyses
emphasize individual components and their interactions, disintegrating the
evident complexity so that it may analyzed piecemeal. Top-down analyses
emphasize extrinsically imposed forces and their physics, to the extent that
they might be determined. Neither analytical approach can be completely
satisfactory because both simplify nature. But neither are they equal in value,
nor do they portend similar philosophies. Bottom-up analyses have inherent
pitfalls. Where even very few components interact, there exists strong
philosophical pressure to speak of "emergent properties,"
describing patterns
of behavior not immediately predictable from the behaviors of the isolated
individual components. The necessity to resort to emergent properties is a
hallmark of any explanatory hypothesis which tends to reverse the actual flow
of evolutionary causation. 

Whenever emergent properties are introduced into a philosophy of evolutionary
design, a higher-order mysteriousness is simultaneously introduced into the
process that treads dangerously close to vitalism. Predictability and, most
especially, inevitability disappear from the process. Evolution, from this
perspective of randomly assembled components, proceeds by the inexplicable fits
and starts of lucky happenstance. 

This view mistates evolutionary causation and tends to make a tautology of the
process. While random variation is the driving force of evolution, selection is
the sole editor of that variation. The survival of the contending phenotypes is
mediated wholly by their various positions on the fitness landscape. The
constant, random reshuffling of system components is assumed in Darwinian
evolutionary theory. Indeed, the reshuffling is inescapable in a hot
Boltzmannian universe. But selection too is inescapable in a finite arena and
those variants that function better than others are differentially retained.
This persistant selection moves a population of Malthusian trials inexorably,
almost deterministically, towards the points of minimum system error on the
adaptive topography. 

Nor is the chain of causation silently evolved; causation leaves its stamp on
the evolved structures. Should the physics of selection act in manner such that
individual coding structures are optimized, from the bottom up, the resulting
genetic basement must then inevitably become a collection of perfected
"genes,"
informationally disconnected from one another, each operating to maximize its
own optimal survival. But should the physics of selection operate only to
minimize total system behavioral error, never directly acting on the coding
structure itself, the result must be wholly reversed. The evolved phenotype
must become composed of highly integrated "organs of extreme
perfection" while
the genetic basement will inevitably become an overlain mixture of co-opted,
duplicated, and highly interdependent code. It is only this second pattern that
is found in nature. 

The celebration of specific detail of a gene, a neuron, or a behavior, in
isolation of its context, is a fundamental error. It has been an unfortunately
common error, the result of which is virtually always a misrepresentation of
not only the fundamental physics of the process of evolution but what is being
evolved. 

I myself have no doubt that random variation in an underlying coding structure
coupled with a stringent selection imposed on resultant variant behaviors is
more than a sufficient mechanism to build very complex organelles, organs and
organisms very quickly.

Wirt Atmar
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