From: bivalve (bivalve@mail.davidson.alumlink.com)
Date: Tue Nov 12 2002 - 13:48:48 EST
>"As a rule, this method will tell us whether the random probability
>is so low as to make another explanation preferable, rather than
>being able to truly rule out random events. The only exception is
>if we can truly assign a zero probability to something."<
>If we take this reasoning, we should accept nicely Dawkins
>explanation of miracle-like events in "The Blind Watchmaker," where
>even if we saw a stone statue waving its hand at us, we should not
>suspect miracle. Rather we should conclude that an extremely low
>probability event occured where the random thermal movement of all
>atoms in the arm of the statue move simultaneously in a given
>direction to produce the effect. <
No, I meant to point out that such an explanation could not be
absolutely ruled out. However, the probability is indeed so low as
to make Dawkin's explanation ridiculously implausible. Arguments
like Dawkin's also tend to confuse the general and specific. The
probability that any randomly selected event involved a miracle is
very low. However, the probability that a putative miracle that
Dawkins wishes to dismiss is a randomly selected event is probably
even lower. This same issue came up in the letters to Science or
Nature a few years ago, when someone wrote in claiming that the very
low probability that a randomly selected human was the pope implied a
high probability that the pope was not human.
>Dembski's method leads us to the best inference, given that we allow
>supernatural explanations to be considered among the possibilities,
>and I think it is a valuable tool.<
If we can make reasonable estimates of the probabilities, something
not currently possible. However, it remains internally consistent,
albeit highly implausible, for the atheist to claim that we just
happen to be incredibly lucky. Another problem is that some ID
advocates (not you) jump to the conclusion that low probabilities
would rule out the possibility that God used natural means to create
these low-probability structures. Low probabilities are equally
compatible with a miraculous creation of the structure and with a
series of low-probability but fully natural reactions, mutations,
etc. occurring under God's providence.
>I think the essence of this problem is: Just how specified is
>biological activity and function among protein sequences?<
Yes; of course other biological molecules are an issue, and there is
the remote possibility that life could have used some other sort of
complex biomolecule besides protein as the major functional elements.
Thus, to prove ID, it would be necessary to identify all possible
ways of making complex life. Less exhaustive data could be adequate
to suggest that the evidence favors it, while recognizing the limits
of our knowledge.
>The critical distinction between the analogy of your computer
>sequence of letters and the formation of life and the generation of
>biological complexity and information is the fact that although a
>computer can generate any sequence of letters, and this can be
>considered specified in any kind of way, biological sequences must
>be specified in a biologically relevant way: sequences must confer
>functional advantages that lead to evolutionarily selective
>adaptations.<
However, the biological relevance is not the specification that has
been the focus of popular ID. Rather, the focus has been on the
degree of complexity, which is replicated by a long random string of
characters.
Also, it is not entirely necessary that sequences confer an
advantage. They must not confer such severe functional disadvantage
as to lead to significant negative selection. Otherwise, they can
persist in a population, though they can also be lost through
mutation and genetic drift if the positive selection pressure is not
strong enough.
>(For example, some percentage of landscape one forms insoluble
proteins which cannot perform any function.)<
Although there are plenty of proteins that do not perform useful
functions (at least, not in light of the biochemistry of known
organisms), insoluble proteins can be useful in association with
lipid membranes, etc.
>Whether these sequences are only islands of function that stand
>above the sea of modern-day requisite biological function verses the
>lower threshold function of pre-biotic or ancient precursor biotic
>system function is a largely-unaddressed and
>completely-open-to-interpretation question, imo.<
This is an important point. The threshold would generally be lower
in such a setting, though how much lower is totally unknown. In
experimental attempts to produce new enzymatic function, the
opportunities for advantageous mutation are initially quitelarge, as
even a little function is better than none. As the functionality of
the novel enzyme increases, the magnitude of improvement diminishes,
until a plateau is reached where several slight improvements and
diminishings are possible. Most enzymes in modern organisms are at
this level, where mutations may slightly improve or diminish their
efficiency, but large improvement seems unlikely. Prebiotic to early
biotic settings would have had a much wider field of opportunity for
innovation.
As before, there is the risk of getting into an argument about the
glass being half full or half empty. Ithink the important point is
agreeing that the relevant probabilities are largely unknown, leaving
different ideas neither proven nor disproven.
My feeling, reflecting both the existing hints of stepwise
construction for some complex biochemical systems (e.g., DNA
translation) and my theological sense of God's usual self-limitation,
suggests that He made extensive use of natural means.
Dr. David Campbell
Old Seashells
University of Alabama
Biodiversity & Systematics
Dept. Biological Sciences
Box 870345
Tuscaloosa, AL 35487 USA
bivalve@mail.davidson.alumlink.com
That is Uncle Joe, taken in the masonic regalia of a Grand Exalted
Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at
Droitgate Spa
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