Striking a balance, weighting and Cladistics

[Thomas DiBenedetto]

-----Original Message-----
From: Zdenìk Skála [mailto:skala at INCOMA.CZ]
>Apart from the weighting discussion: the parsimony criterion (in the
>cladistic sense) of course *is* an assumption about the underlying reality
>as well as methodological principle. Otherwise, phylogenetic analysis 
>could not even converge to the supposed real phylogenetic tree topology. 
>If the phylogeny would not be parsimonious, the pattern we are revealing 
>has nothing to do with the phylogeny.

I disagree. Look at it this way. You have an underlying reality. As an
overlay on top of that you have a mass of evidence, often confusing and
contradictory, that you must sort through in order to percieve the outlines
of the reality. The parsimony criterion deals with the process of sorting
through the evidence layer, it essentially dictates that one must accept the
patterns in the evidence that are strongest, i.e. the weight of the
evidence. This does not in any way place any limitations on the complexity
of the underlying reality.
I think that the entire history of science argues in favor of this
perspective. Parsimony is an inherent criterion in much of what we do in
science (and in every day life as well), and the use of this criterion has
not inhibited us from confronting and understanding extremely complex
systems.
-tom