[Taxacom] Molecular data and synapomorphies

J. Kirk Fitzhugh kfitzhug at nhm.org
Wed Dec 3 16:42:12 CST 2008

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

Fair enough.  But, in that case, you can't refer to cladograms inferred 
from partitioned data as being the same class of explanatory construct 
because they would have to be inferred from very different causal 
theories.  To wit, you can't speak of any comparisons of 'tree 
topologies'  inferred from partitioned data.  The branching diagrams 
could not have the same causal meaning if one is going to assert that 
they are answering entirely different sorts of questions.  The two 
diagrams would have to be irrelevant to one another.  But when one does 
make those comparisons, which systematists do too often, then they've 
violated the requirement of total evidence.

J. Kirk Fitzhugh, Ph.D.
Curator of Polychaetes
Invertebrate Zoology Section
Research & Collections Branch
Natural History Museum of Los Angeles County
900 Exposition Blvd
Los Angeles CA 90007
Phone: 213-763-3233
FAX: 213-746-2999
e-mail: kfitzhug at nhm.org

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