[Taxacom] Molecular data and synapomorphies

Richard Zander Richard.Zander at mobot.org
Wed Dec 3 16:20:43 CST 2008


Kirk Fitzhugh wrote:
"Ah, but only if the requirement of total evidence could be so easily
dismissed!  It can't -- which should come as no surprise, given that no
philosophers of science have shown how one could rationally do without
it.  The causal questions being asked of sequence data are no different
from those asked of any other properties of organisms to which
phylogenetic theories are being applied."

My response:
Sure, if the total evidence was dealt with properly. Take clues to a
quotation, one a cryptogram, the other piece of paper in a Chinese
puzzle box. Do we combine the method of figuring out the quotation? Or
use different methods? THIS assumes the quotation is the same in both
puzzles.

Suppose the quotation is different? Suppose the QUESTION for molecular
data was what are the paths of genetic continuity and the QUESTION for
morphological data was what are the boundaries of groups of organisms
retaining similarity (about a mode) perhaps by normalizing selection
over millions of years? It may be that the answer to one question will
help with the other or there may be emergent properties associated with
answering both questions and combining the answers.

I'm all for holism, don't get me wrong. But the causal questions are
about different phenomena. 

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Missouri Botanical Garden
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richard.zander at mobot.org
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