Uko Zylstra, Ph.D.
Biology Department
Calvin College
tel: (616)957-6499
email: zylu@calvin.edu
>>> "Howard J. Van Till" <hvantill@novagate.com> 10/08/01 04:04PM >>>
Uko,
Thanks for the response. Let me try again to get these distinctions clear in
my head.
I had asked:
> 2. Where would genetic relationships among extant and recent species fall?
> Would that be counted as evidence that there was a (2) process of evolution
> that occurred, even if details re (3) mechanism are not fully known?
To which you reply:
> I would consider genetic homology and other molecular and morphological
> homologies to be evidence for evolution as pattern. They all contribute to a
> picture of phylogenetic relationships, but they do not give us and
> understanding of how such relationships came to be.
OK, but then I'm led to ask 2 more questions:
1. What kind of empirical evidence would contribute toward a knowledge of
process?
2. Does mechanism have to be known before process?
Howard
Good questions. With regard to the question concerning empirical evidence to
process, I think we need evidence for the transition (at the very least,
evidence that points to the transition) from ancestor to descendent. In other
words, we need evidence that at least enables us to conceptualize the
development of another stage or acquisition of another structure. We will
undoubtedly differ in our criteria for such conceptualization. But I would
judge, for example, that Ken Miller's account of the evolution of the cilium in
response to Behe's claim that Darwinian gradual evolution is inadequate to
account for the evolution of the cilium, is still nothing more than an account
of the pattern of evolution. He also has not given an adequate explanation of
the mechanism of the evolution of the cilium either. I think he still fails to
address Behe's basic thesis. Miller is still left with pattern and he continues
to convince himself that he has accounted for the process.
Concerning the second question, does mechanism have to be known before the
process? I would say no. We might well be able to give an account of the process
without understanding the mechanism. Natural selection as the chief proposed
mechanism for the process of evolution falls short of serving as an adequate
explanation for much of the process of evolution. Simply because natural
selection does occur, doesn't mean that it is sufficient to account for the
extensive evolutionary processes that have taken place. In my view, evolutionary
biologists loose scientific credibility when the continue to impose a mechanism
on processes regardless of whether there is sound empirical evidence for doing
so. Extrapolation or speculation me be appropriate, but then it must also be
recognized as such. What is basically need is more scientific honesty. Lack of
alternative explanations is not a form of empirical evidence.
Perhaps my comments raise more questions about my original comments concerning
the meanings of evolution. But I do think it is very legitimate to ask for the
empirical evidence for process as well as mechanism for the pattern of
evolution.
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