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Re: A Clutter of Duckbills
> Why can't we set a criteria as to which species and genus goes where?
No problem; put the little ones on the top shelves, the big ones
on the bottom shelves, and the real big ones in the basement, so the
floor won't collapse under them.
Wait! Wait! I'm serious! At least, I am trying to make the
point, that before one can decide how to construct a taxonomy -- a
classification or organization of things -- one must first decide what
purpose the taxonomy is to serve. "Little ones on the top shelves,
big ones on the bottom shelves" is an entirely reasonable taxonomy for
the organization of a stored collection.
There are of course other purposes. Many taxonomies have been
constructed for the purpose of identifying things quickly in the
field. Thus for example, in one popular and successful guide to
modern birds, birds of the same color are grouped together, because
color is one of the easiest things to tell at a glance in the field.
That is surely a very useful taxonomy.
A museum collection organized for educational viewing might have a
taxonomy that grouped very *different* creatures close together, the
better to show those differences clearly to uninformed laypersons.
Of course, the biological taxonomies we mostly have in mind
generally have the purpose -- sometimes unstated -- of reflecting
biological relationships among creatures, and since most of us believe
that those relationships stem from evolution, these taxonomies ought
to group creatures based on the actual phylogeny that took place. That
is, if we had a big family tree of everything that ever lived, we
would be cutting off branches and sprays of varying size, and labeling
them with taxonomic names. We would no doubt argue a lot about what
names went on what branches, and about how big a branch ought to
have what kind of name (class, order, family, genus, species...), but
at least we would know what it was that we had to cut up and label.
(And I want my personal branch to be labeled "Freeman".)
Unhappily, we don't have the grand universal family tree all done
just yet. There are still a few nagging little doubts about what goes
where. Therefore, persons who wish to construct taxonomies based on
phylogenetic relationships quite literally do not know what they are
talking about. Or at least, they don't know everything they probably
would like to know about what they are talking about.
Notwithstanding, they do keep talking. But after all, what fun
would an argument be if we had a chance of ending it?
-- Jay Freeman