Positivism in evolutionary science

Tom DiBenedetto tdib at UMICH.EDU
Wed Dec 3 11:58:16 CST 1997

Richard Zander wrote:

> my own problem with explanation in
>phylogenetic inference is that it is used to get us to accept the
>most-adequate hypothesis from a group of competing hypotheses instead of
>demanding, as we should, that a hypothesis should be adequate just
>standing alone.

I think that most of the nodes in a "usual" parsimony analysis have
more evidence for them than against them. Do you agree?

> The best (most-adequate) hypothesis does, in fact,
>explain a data set as well as the available information allows, but the
>best hypothesis, if not having more evidence for it than against it
>(P>.5), is not adequate in view of the number of other almost-best

I dont see anything wrong with accepting the best available
explanation of the data, especially since no one would ever claim
that we should stop trying to improve the dataset.  Do you assume
that a probability can be meaningfully calculated for phylogenetic
data in the absence of solid knowledge of the relevant processes?

> This use of explanation in phylogenetic analysis is
>sophistry at best, and like least falsifiability, maximum likelihood,
>and maximum posterior probability, is just a ploy to substitute an
>attainable goal for a presently unattainable or rarely attainable goal
>(a probabilistic hypothesis of evolution).

Is there something wrong with ignoring the search for an unattainable
goal and concentrating on an attainable one?

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

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