Re: the definitions of evolution

From: Uko Zylstra (
Date: Tue Oct 09 2001 - 21:10:29 EDT

  • Next message: "The First Commandment"

    Uko Zylstra, Ph.D.
    Biology Department
    Calvin College
    tel: (616)957-6499

    >>> "Howard J. Van Till" <> 10/08/01 04:04PM >>>

    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

    2. Does mechanism have to be known before process?


    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

    This archive was generated by hypermail 2b29 : Tue Oct 09 2001 - 21:11:27 EDT