Taxonomy as science

Peter Fritsch fritschp at ACPUB.DUKE.EDU
Mon Apr 1 11:06:10 CST 1996

>So, then, let me see if I get this straight. If a taxonomist is trying to
>decidee whether two species should be placed in the same genus or not,
>s/he sets up alternative hyoptheses:
>H1: The species are congeneric, vs.
>H0: The species are not congeneric.
>S/he then sets up an experiment to test whether s/he can demonstrate one
>hypothesis or the other with 95% confidence. Do I have this right? I have
>never seen any taxonomist do anything of the sort.

I am saying that to reason that taxonomy is not a science because different
conclusions can be reached by two researchers is not valid; in fact, the
problem of subjective interpretation is inherent to even the most rigorous
of scientific endeavors.  There is no universal law that says the decision
rule level must be set at 19/20--where one sets the decision rule level is
often determined by the nature of the study, e.g.  environmental studies
that relax alpha at the expense of power.

Furthermore, there are numerous taxonomic studies that employ statistics
such as Mahalanobis distances, which can be tested for significant
difference, i.e., Syst. Bot. 19:539. 1994.  This is one approach.  Another
is to compare the likelihood of one or two species with respect to various
species concepts, given the data at hand.  I have a paper (Aliso, 1996 in
press) which does just that--I justify two species using morphological,
biological, and phylogenetic species concepts, given morphological,
isozyme, and phylogenetic evidence.

Finally, there is the issue of whether science must placed exclusively in
the Popperian framework.  I do not think it does; that is, I accept
inference as a valid scientific approach.  After all, I do study evolution.

Whether a classicalist
>examining dusty old herbarium specimens with a hand-lens, or a cladist
>producing computer-generated tree diagrams, it still always comes down to
>a question of personal judgment as whether to call a given monophyletic
>group one genus [familiy, order, etc.] or more than one. There is no
>universal consensus whatsoever on how to do this.

This is a question of rank, and, I agree, is completely subjective in the
absence of any standardized protocol for naming things.  To me, though,
rank is a clerical and trivial part of taxonomy--the interesting part is
circumscription, and this is what I consider to be the scientific part of

Peter Fritsch                  ph:  (919)660-7369
Department of Botany           fax: (919)684-5412
Duke University                e-mail: fritschp at
Durham, NC 27708-0339 USA

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