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RE: birds are birds, dogs are dogs




From: NJPharris (12/05/2000 6:35 PM):

>I for one prefer to see the set of descendants of a particular ancestor as
an 
entity and to view the advent of subgroups that fly, swim, walk on land,
have 
backbones, regulate their body temperature, etc., as interesting things that

may *happen to* such an entity.<

and 12/05/2000 7:32 PM): 

>However, I would still assert that those who would remove birds from 
Dinosauria fail to appreciate that when the birds came along, they *expanded

the boundaries of what it means to be a dinosaur*, rather than somehow 
leaving the group.<

Not in PT.  Dinosaurs are dinosaurs by ancestry, i.e., if you are a
dinosaur, that MEANS you have particular ancestors.  Birds did , however,
make the group considerably larger.  In fact, it appears that any such "set"
can only get larger with time, at least until the lineage becomes extinct,
whereupon its limits are fixed.  Up to that point, all sorts of "interesting
things" may have happened to it, but nothing changed the meaning of the
term.  

By one way of looking at it, we have lost a lot in using PT definitions,
whether or not they are more objective.  Such definitions may indeed be
easier to apply, but they have less meaning to us in the real world.  To get
to where we were before, you have to specify "bird", or at least "avian
dinosaur."  Then all the sudden a light comes on in your brian and you
realize what is being referred to.  Admit it guys, that is exactly what
happens!  The reality that dinosaurs evolved into birds and there are some
animals that seem to fall on a borderline, that there are both bird-like
dinosaurs and dinosaur-like birds, doesn't change anything.  Why don't we
just decide that henceforth PT will be used for all taxonomic groups except
birds, and be done with this debate once and for all?  What good is logic
without wisdom?  That's the way computers operate.  They follow the
algorithm exactly, often to your embarrassment if the algorithm was flawed.
Then you have to intervene to make the computer (= taxonomy?) spout out
something that is useful.