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Re: Some thoughts on cladistics



----- Original Message -----
From: "philidor11" <philidor11@snet.net>
Sent: Saturday, November 03, 2001 1:51 PM


> <Unless you consider every species transitional, but if everything is
> transitional, that nullifies the meaning of "transitional."  It's all or
> none.>
>
> Well, no.
> Every species with one or more descendant species is by definition
> transitional between its ancestor species and its descendant species.

This isn't discussed. The point is that "evolutionary systematics" can,
additionally, declare species or higher groups as transitional between e. g.
reptiles and mammals, reptiles and birds or whatever. Here the cladistic
criticism is that this kind of transition is a complete artefact produced by
the recognition of paraphyletic groups, ...

> <That's a fundamental flaw with a hierarchical system that assumes
> archetypes.  Everything that is different must be a transition to those
> archetypes from other archetypes, which is an idea that is inherently
> flawed.>

... and that these paraphyletic groups are based on some sort of archetypes

> Philosophically, an archetype is the unknowable [...]
> model that the observable is expressing imperfectly.

Gould's book Full House gives a good summary of that, and writes that in
biology the observable variation is the real thing and not just variations
from an archetype which doesn't exist anyway.

> As I understand it, a
> system based on observation is Aristotelian, not Platonic.

Probably correct, but I don't understand what you are aiming at with this.

> If you are
> looking for what distinguishes a species from all other species, you are
> diagnosing the essential aspects of that species.

Actually true. With the difference that, at least for clades, phylogenetic
systematics use the last common ancestor instead of an archetype. The
ancestor at least existed :-)

> It's interesting that in biology the word 'archetype' has been used to
> define a basic body plan, a template for a variety of species.  That's an
> attempt to formulate what looks like an archetype.

That's true. However, these "basic body plans" (aka "Bauplan") have never
been regarded as very serious by those who drew them, and they haven't been
used very much in classification.

> But since it's based on
> commonalities in observation,

(And) of interpretation.

> I think it escapes being Platonic.

I don't know, and, as a phylogenetic taxonomist :-> , I don't care... it
isn't necessarily better if Aristoteles or someone else said it.

> Or maybe
> biologists are philosophers(?).

Some have tried (AFAIK rather unsuccessfully). Some philosophers have tried
to intrude biology (with even less success). In general scientists seem to
disregard the endless discussions about what philosophy Hawkins adheres to
where in his writings, and think that philosophies should -- if at all -- be
formed after theories, not before.

> Still, science definitely has emphasized observation over inference.
> Aristotle said that when two metal balls are dropped from a height, the
> heavier will fall faster.  A guy named Galileo went to the top of a tower
> and tested it.  Aristotle was wrong.
> Inference can never replace direct testing in science, now can it?

Of course not, where do you see that happening?