arbitrariness

Nico M. Franz nmf2 at CORNELL.EDU
Thu Jul 3 15:39:27 CDT 2003


I'm sure this has come up many times before in discussions, but it seems to
me that one ought to begin with a very thorough assessment of the kinds of
communication services ranks can and do provide to systematists and other
users of classificatory information. Very few heavily used things in
science last over 200 years while having serious flaws. Conveying
information about nestedness is something that ordinary names (like
"Cicero" or "table") don't have to do, but in the case in biology it
apparently does help to say that these two species are in different
families but just listing the respective names. Although the initial
baptism of a ranked taxon bears an element of arbitrariness, the meaning
they receive (or lose) over decades of research is anything but that. So in
general it's not that difficult to find solid conceptual backing in
contemporary philosophy of language for most of the practices that Linnean
systematists have come to adopt. There's an IMO excellent paper (Keller, R.
A., Boyd, R. N., and Q. D. Wheeler. 2003. The illogical basis of
phylogenetic nomenclature. The Botanical Review 69: 93-110.) coming out
soon on these issues. Cheers!

Nico M. Franz
Department of Entomology
Cornell University
Ithaca, NY 14853

Phone: (607) 255-8050; Fax: (607) 255-0939; E-mail: nmf2 at cornell.edu
Website: http://www.cals.cornell.edu/dept/entomology/wheeler/Franz/Nico.html



>This still doesn't solve the problem of where to place ancestral species.
>
>You could possibly get around the problem of running out of ranks by leaving
>many taxa unnamed, e.g., for Vertebrata, make Classes out of Pteraspidomorphi,
>Chondrichthyes (sense stricto), Actinopterygii, Dipnoi, Coelacanthomorpha,
>Lissamphibia, Mammalia, Testudines, Lepidosauria, Crocodylia, and Aves. But
>then you leave a lot of fossil taxa with no Class (_Ichthyostega_,
>_Dimetrodon_, etc.). Furthermore, you have sacrificed such taxa as
>Gnathostomata, Osteichthyes, Sarcopterygii, Tetrapoda, Amniota, Sauropsida,
>Sauria, and Archosauria. I don't see that keeping the arbitrary ranks is worth
>this sacrifice.
>
>I agree that all formal taxa should be clades (or species ... I think), but I
>don't see how this is workable with the Linnaean hierarchy of absolute ranks.
>Nor do I see the real value of absolute ranks. (Look above -- what is
>gained by
>saying that Dipnoi [lungfishes] and Mammalia are Classes?)
>
>=====
>=====> T. Michael Keesey <keesey at bigfoot.com>
>=====> The Dinosauricon <http://dinosauricon.com>
>=====> BloodySteak <http://bloodysteak.com




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