Classification: A Definition

["Jerry D. Harris" <jharris@dixie.edu>]

Awhile back, Mike Keesey wrote:

> As David pointed out, phylogenetic nomenclature is not classification;
it's an alternative to classification.

I must admit, this comment has been nagging at me, but I've been unable to 
get on a computer long enough 'til now to ask further about it.  Now, I 
hain't got nuthin' agin phylogenetic nomenclature -- as a matter of course, 
I find it far superior to the ol' Linnean system and have happily abandoned 
the latter -- but I'm curious about its perception as not being a form of 
classification.  Considering the following more or less typical definitions 
of "classification":

MERRIAM-WEBSTER
-------------------------
1: the act or process of classifying. 2 a: systematic arrangement in groups 
or categories according to established criteria; specifically : taxonomy b: 
class, category

OXFORD ENGLISH DICTIONARY
---------------------------------------
1. The action of classifying or arranging in classes, according to common 
characteristics or affinities; assignment to the proper class.
2. The result of classifying; a systematic distribution, allocation, or 
arrangement, in a class or classes; esp. of things which form the 
subject-matter of a science or of a methodic inquiry.

(Noting, of course, that "class" here is used in a philosophical sense, not 
a Linnean one.)  I don't quite see how phylogenetic nomenclature -- well, 
phylogenetic systematics, that is, which is technically distinct from but 
inextricably linked to phylogenetic nomenclature (one is kind of useless 
without the other) -- doesn't meet these criteria.  The nomenclature is a 
means of providing names to entities (classes) that exist/are ascertained to 
exist based on evolutionary descent; this differs from the Linnean system of 
providing names to entities based on a few gross physical similarities, sans 
regard to evolutionary relationships.  Either way, it's using a set of 
criteria to designate (i.e., name) groups.  Perhaps not categorization per 
se -- certainly not in the Linnean sense of ranks! -- but still seems to me 
to be classification.  _Tyrannosaurus_ is still classified as a member of 
the Coelurosauria, Tetanurae, Theropoda, Dinosauria, Archosauria, Tetrapoda, 
Vertebrata, etc., though not for the same reasons (and obviously not some of 
the same groups) as it had been previously.  I guess I'm not seeing how 
determining a taxon to be in some set of clades doesn't qualify as 
classification.  I can see that phylogenetic NOMENCLATURE is _in itself_ not 
classification (not without the systematics part), but it also isn't an 
_alternative_ to classification.  Or am I missing the point here?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jerry D. Harris
Director of Paleontology
Dixie State College
Science Building
225 South 700 East
St. George, UT  84770   USA
Phone: (435) 652-7758
Fax: (435) 656-4022
E-mail: jharris@dixie.edu
and     dinogami@gmail.com
http://cactus.dixie.edu/jharris/

"Trying to estimate the divergence times
of fungal, algal or prokaryotic groups on
the basis of a partial reptilian fossil and
protein sequences from mice and humans
is like trying to decipher Demotic Egyptian with
the help of an odometer and the Oxford
English Dictionary."
              -- D. Graur & W. Martin (_Trends
                  in Genetics_ 20[2], 2004)