Three-taxon analysis

P.Hovenkamp Hovenkamp at NHN.LEIDENUNIV.NL
Thu Apr 10 10:40:30 CDT 2003

Many of the points have already been answered by Pierre Deleporte, so I'll 
just add a few comments.

At 12:40 PM 4/8/03 +0200, René Zaragüeta i Bagils wrote:

>We agree. Now you talk pattern. Mechanisms come after, this was what I tried
>to say.
(no comment)

>"When I was at secondary school, we used to amuse ourselves by proving
>anything at all with series of impressive looking formula's, which on
>closer inspection always included a division by zero somewhere. All this
>elaborate reasoning strongly reminds me of that period. Once you start
>misapplying terms you can "prove" anything. Characters cannot be
>paraphyletic. The term does not apply. It is as simple as that."
>Cladistic analysis is analysis, that means that what you know about the
>whole is (no more that) what you know about the parts. The whole are taxa,
>the parts are characters. These are no impressive formulae. If paraphyly
>applies to taxa, it applies to characters, because taxa are composed of
>characters (or cladistic analysis is not analysis).
Sorry - we may be having some linguistic misunderstandings. I was using an 
analogy. Looking at the elaborate papers by some 3TA-proponents, I still 
think the term "impressive formula" is not really misapplied.
Apart from that, this passage is again a perfect example of a misapplied 
term, this time compounded with a logical error. Taxa are not "composed of" 
characters. Even if they were, it is not necessarily the case that anything 
that applies to a whole, also applies to its parts. My name applies to me, 
but does it apply to my toenails?

>"Never ask for certainty unless you can offer it. You can test the assertion
>by looking for counterexamples. As you can any assertion."
>I cannot give you any certainity. But your construction of multistate
>characters uses certainty, at least that they are "states" of the "same"
Why would this be "certainty"? You seem to expect certainty of all your 
opponents before you let yourself be convinced. Yet, whenever you suspect 
certainty, you come up with the truism that certainty is impossible. Please 
be consistent.

>I do not understand what do you mean by "counterexamples" in this
>case. (the case being my assertion that characters do not arise "de novo")
A simple counterexample would be a character that did arise "de novo". But 
would you be able to recognise it? Not with certainty, that's for sure...;-)

>"Can we make any observations at all? If you say
>no, then retreat from science. If you say yes, you'd better start asking
>yourself how we do it instead of simply trying to deny we can."
>OK, it seems my English is really bad! The point is that the ultimate source
>of knowledge are not observations. This is not my idea, but Karl Popper's.
Again, debatable. Popper's point of view is a little more subtle.

>You cannot learn anything from observations alone, you need a theory FIRST
>to know what to observe (observations can only be tests of theories).

Please read back your posts before sending them off. The discrepancy 
between this statement and your first one (retained in this post without 
comment) is so glaring that it should have made you think twice.

Peter Hovenkamp

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