>SC>Maybe it's just a matter of semantics, but if residual genetic
>>information
>>for the "vitamin C" gene is present in the human genome, then there is
>>likely a genetic reason (defect if you will) why it is not expressed.
>
>There may be a genetic explanation, but not necessarily a genetic
>"reason"? (More "semantics"! <g>)
Yup. How about genetic "mechanism"?
>SC>On
>>point 2, I am uncertain by what "common degeneration" means. If you mean
>>that precisely the same 'defect' that prevents the gene from being expressed
>>could have arisen independently that is very unlikely and would probably be
>>eliminated by sequence analysis of the pseudogene.
>
>Why is this "very unlikely"? Look at the numerous examples of
>parallel evolution. Look at the guinea pig which has the same
>"defect".
There is an important distinction in the way that we use "defect". In my
use of the word, I do not intend to broadly mean "defective" which i
understand you to mean. By "defect" I refer to the precise mechanism by
which the gene is made non-functional. I suspect, from my knowledge of
genetics (but do not know for certain), that the guinea pig would have a
different molecular defect than primates in the gene in question (indeed
different species of primates may have different genetic malfunctions).
Your point that parallel evolution explains my "unlikely" statement doesn't
really alter the point. Here we seem to be talking at different levels
since "parallel evolution" is a very broad concept in relation to molecular
genetics. Parallel evolution could feasibly occur by affecting completely
different genes or by affecting the same gene in different ways in distinct
species which is what my question addresses.
If guinea pigs and primates share identical genetic defects that prevent
expression of the enzyme required for vit C synthesis, some might say that
this is evidence for parallel genetic evolution, and suggest that this
provides evidence that the common genetic defect is highly selectable (this
of course is a circular argument). However, as I stated previously, it
would be very unlikely that guinea pigs and primates have identical
molecular defects in the gene. From what we know about genetics and
regulation of gene expression, a multitude of molecular defects could render
a gene unexpressable. For this reason, I highly suspect (but do not
know--but could probably find out) that distinct molecular changes
inactivate the gene in guinea pigs vs primates. However, if the genetic
defects were identical, one could conclude that this would indicate that
there is something in common between guinea pigs and primates. Since common
descent is not a likely explanation in this case (otherwise other species
would likely have the same genetic defect--this could feasibly be tested),
it would be reasonable to consider common evolutionary selection.
Logically, it would also be very reasonable to consider common design.
>SC>On the other hand, if
>>identical 'defects' in the gene were shared by different primate species,
here, I should have added, "and not shared by guinea pigs,
it
>>would almost certainly be due to common inheritance.
>I disagree with the "almost certainly" bit. It could equally be by
>common design. Even if it was by "common inheritance", this does not
>prove that Darwinist mechanisms were the cause. These need to be
>proved in their own right.
By offering a offering common design as an alternative explanation to common
inheritance, you infer that design and common descent are mutually
exclusive. Certainly common design could occur separately from common
inheritance, and I assume that this is the scenario that you are considering
here. However, it is also possible that common design could incorporate
common inheritance. From the hypothetical data presented above, there is no
way to distinguish between these explanations.
The genetic data I postulated above would be consistent with the proposed
mechanism of evolution by common descent, and would provide no reason to
discard the evolutionary hypothesis (which is the best claim that any
experiment can legitimately make). You are correct that the data would also
be compatible with common design, but also with martians molding us out of
clay, firing us in ovens and sprinkling us with magic dust to become
animate.... The problem with the last two explanations, is that they are
only metaphysical and not mechanistic.
Now, before you protest that common design is a mechanistic theory, tell me
how such a mechanisms would be distinguished from common origins. Keep in
mind that above, I admitted that common origins does not rule out design.
Since I include design within the philosophical framework of common origins,
and since you don't like common origins, and seem to want to exclude this
from design, then the onus is on you to explain how you would distinguish
the difference.
much clipping....
>SJ>Why is not Progressive Creation not also "an interesting and useful
>>theory.">
It may be. I know very little about the evidence for or against it. Until
I joined the reflector, I knew very little about the argument for design.
While well schooled in the theory of evolution, evolution was never really
central to anything in my science or philosophy. I guess you could say that
the whole matter is really of little interest to me (or to most of my
colleagues and students).
So why am I talking to you? From the exposure I did have to the debate,
largely beginning with Phil Johnson's book, I became interested in the
debate itself. In particular, I am interested in the different conceptions
of science embraced by the different sides of the debate. While I firmly
agree that Dawkins, Huxley, et al., claim too much for science and mistake
philosophy for fact, unfortunately I see the same mistake made by all sides
of the creation arguement. Parenthetically, my interest in the philosophy
of science also traces to my experiences in training students and
post-doctoral fellows in my lab and classes. Over the last few years, I
have come to the conclusion that we don't train philosophers, as the PhD
would imply, rather we train technicians. This is because most of my
colleagues know nothing about the philosophy of science themselves--hence
the garbage that comes from the writings of well respected scientists, and
this explains my contention that my colleagues have very little interest in
the evolution debate and in any resulting theistic implications.
In sum, your argument against common descent and for design cannot be
adressed by science in the way that you present it. Like Dawkins, you focus
on your interpretation as science and fact. However, the science is
represented by the data collected and that alone is factual. The
interpretation, regardless whether it is from Dawkins or yourself, is
metaphysics. The problem lies in the latter and not with the former. The
debate would facilitated by recognizing this distinction and focusing
discussion at the metaphysical level.
Cheers,
Steve
____________________________________________________________________________
Steven S. Clark, Ph.D. Phone: (608) 263-9137
Associate Professor FAX: (608) 263-4226
Dept. of Human Oncology and email: ssclark@facstaff.wisc.edu
UW Comprehensive Cancer Ctr
University of Wisconsin "It is the glory of God to conceal a
Madison, WI 53792 matter, but the glory of kings to
search out a matter."
____________________________________________________________________________