Felsenstein versus Ockham

Tom DiBenedetto tdib at UMICH.EDU
Fri Jan 22 19:56:58 CST 1999


>In my opinion, simplicity is justified to the extent that
>nature is parsimonious; it is, but not optimally so.

That may be your view, but it is not the justification used by cladists, nor, I think, by scientists in general who use a
parsimony critereon. Parsimony is a logical discipline; it states that for any given set of adequate explanations for real
world phenomena, one prefers the less complex. As Newton ( I think it was) put it; "do not postulate complexity
unneccesarily". This says nothing about how complex or parsimonious the real world is. One must explain whatever
complexity one discovers, and there is nothing about the parsimony principle which constrains such discoveries.

> Both the parsimonists and t
>he statistical phylogeneticists err when they use optimality criteria to estimate a
>point when an interval is better justified by contradictions in the data.

I dont understand what you mean by this. The only optimality critereon in cladistic parsimony is that one report only
those evolutionary transformations that are indicated by the data and by the assumptions of a hierarchical branching
pattern.



Tom DiBenedetto                   tdib at umich.edu
Museum of Zoology                 http://www-personal.umich.edu/~tdib
University of Michigan              734-647-2192




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