multiple classification systems

Barbara Ertter ertter at UCJEPS.HERB.BERKELEY.EDU
Mon Jun 16 10:20:43 CDT 1997


Following up on Lammers' and Sosef's comments, one point I was trying to
make in my earlier posting is that an independent classification system
based purely on branching systems is already in use; it's called a
cladogram.  The fact that it does not easily shoehorn into the Linnaean
hierarchy is a problem only because of the unsupported notion that there
can be one and only one valid way of parsing nature into units that are
meaningful, units that we need to communicate.  Whether we acknowledge it
or not, operationally we routinely use a diversity of classification
systems already. If I am focusing on branching patterns, I can speak of the
X clade; if I am focusing on biosystematics, I can speak of the Y species
complex, and if I am doing wetland delineation, I can speak of aquatics.
And I do, and we all do.  The general purpose units referred to by the
Linnaean system are not single-focus, but instead balance what we know
about branching pattern, biosystematics, gene flow, degree of genetic
divergence, degree of ecological divergence, and other equally significant
attributes.  A great majority of the heated arguments about which is most
important, most "natural", fall into the "blind men and the elephant" type
of debate.

The preceding paragraph addresses multiple classification systems that have
a "natural" underpinning independent of anthropocentric interests (tho the
names themselves are a purely human artifact).  At the risk of diverting
attention from this fact, I want to nevertheless note the existence of
multiple purely anthropocentric classification schemes (edibility, color,
flammibility, alphabetical sequence, etc. etc.).  I do this to emphasize
that cognitively we are fully capable of simultaneously maintaining
multiple classification schemes without getting bogged down in horrendous
confusion.  Where we do get bogged down is when we don't realize that more
than one classification system is in play.  The scorn that has been heaped
on ethnological classification schemes based on the useful-not useful
dichotomy is accordingly misplaced, as equivalent to insisting that
supermarkets be reorganized to reflect cladistic relationships.  My
favorite recent example was in a Darwin quiz in a recent journal (apologies
to the author for not having it at hand; I think it was in American
Scientist) that had fun with the historical fact of an early Pope declaring
that capybara are "fish" for the purpose of Friday abstinence from meat.
This seems nonsensical to us, in spite of the fact that we tend not to give
a second thought to the fact "fish" in the culinary classification scheme
already includes crustaceans and mollusks; cabybara are at least
vertebrates! (I've been waiting for a chance to throw that one out . . .)

Barbara Ertter
University and Jepson Herbaria
University of California, Berkeley




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