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Re: Kileskus and Proceratosauridae
"It is true, in fact, that "monophyletic clade" may be a tautology,"
Not picking on any one person here, but a semantic question
nonetheless: How can "monophyletic clade" be construed as a tautology?
It's merely redundant. A phrase like "big giant" or "fast speedster"
is not, itself, tautological; it just repeats the same concept with
AFAIK, a true tautology is a form of argumentation in which two
unsubstantiated points are cited as mutual evidence, each supposedly
proving the other, but neither being critically examined. The classic
example I was taught was, to paraphrase, "for a long time, scientists
would argue that dinosaurs had to have been cold-blooded, because they
were reptiles, but then they would turn around and argue that
dinosaurs must have been reptiles, because they were cold-blooded."
The veracity of the example aside, it does illustrate a proper
tautology (IIRC): neither argument has been demonstrated to
satisfaction by independent observations, yet each is cited as
evidence when the other is questioned. It's a loop where the argument
goes in circles, an untested claim being cited as proof for another
untested claim - and then vice-versa when challenged.
As for my opinion of paraphyletic "clades," I do have to object to
that terminology. There's already a perfectly legitimate term for
that: grades. Since grades =/= clades, and since "grade" by usual
definition refers to a paraphyletic assemblage of taxa, using "clades"
in such a context is extraneous at best. It's pointless as phraseology