Positivism in evolutionary scienc

Tom DiBenedetto tdib at UMICH.EDU
Sat Dec 6 11:36:57 CST 1997

On Sat, 6 Dec 1997 13:30:46 EST, MAGarland wrote:

>In a message dated 97-12-06 03:40:13 EST, tdib at UMICH.EDU writes:
>>  rather homology is assumed because your homology hypotheses have
>>  already been corroborated by all the tests you impose on them in your
>>  work as a biologist (anatomist, behaviorist etc.). IOW, you have
>>  already accepted them as homologies in light of all your biological
>>  knowledge; the test of congruence is merely one last test.

>"Already accepted"?  "Merely one last test"?  Hmmm...reminds me of a passage
>in Sneath (Syst. Biol. 44:286. 1995):

>"The rise of interest in Hennigian cladistics...was to me very surprising.  It
>seemed obvious that if one could be certain of evolutionary homologies and
>ancestral and descendant character states then the reconstruction of phylogeny
>would be straightforward."

Who said certain? All I said was that we arrive, at the end of our
biological studies, with a set of homology hypotheses that we
(conditionally) accept. Have you never arrived at the point where you
are willing to accept a conclusion (while forever remaining open, of
course, to further evidence)?
Reconstruction would be straightforward if we could be both certain,
and correct, but since we are never the one, and only hopefully the
other, we submit our conclusions to a further test.

>"But I found it hard to believe that these
>homologies and states could be determined in the naive fashion that was

I'm not sure what he is referring to here. The traditions and
methodologies of comparative anatomy have never struck me as
particularly naive.

Tom DiBenedetto                 http://www-personal.umich.edu/~tdib/
Fish Division                                   tdib at umich.edu
University of Michigan Museum of Zoology

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