Darwin-L Message Log 8:4 (April 1994)

Academic Discussion on the History and Theory of the Historical Sciences

This is one message from the Archives of Darwin-L (1993–1997), a professional discussion group on the history and theory of the historical sciences.

Note: Additional publications on evolution and the historical sciences by the Darwin-L list owner are available on SSRN.

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<8:4>From Kim.Sterelny@vuw.ac.nz  Sat Apr  2 23:58:55 1994

Date: Sun, 3 Apr 1994 17:58:38 +1200
To: darwin-l@ukanaix.cc.ukans.edu
From: Kim.Sterelny@vuw.ac.nz
Subject: Re: cladistics & distance data

While being somewhat wary of reproducing the typological fallacies in
discussing evolutionary theory that were so hard to remove from that theory
itself, I find myself in mild disagreement both with Bob O'Hara and with
the dissident Toomey on the identification of cladism. Toomey writes:

>I am going to have to respectfully disagree.  If intentions are all that is
>required for a technique to be cladistic, then much of the post
>acceptance of Darwin (Charles, that is) systematic work is cladistic.
>At least this would be the case in vertebrate paleontology (my field).
>The goal and purpose of much of the research has been to reconstruct
>the phylogeny of organisms.  However, I would be hard-pressed to
>describe the gestalt based hypotheses of relationships popular in the
>nineteenth and early twentieth century as cladistic.  (This is not to
>say that the proposed relationships were necessarily incorrect, only
>that the basis for the phylogenies were not explicitly stated.)
>
>Instead, I would say that cladistic refers to a procedure rather than an
>intention.  I think that there is a feature necessary and sufficient for a
>method to be considered cladistic (the synapomorphy of cladistic
>methods, if you will).  This feature is that cladistic methods must make
>an explicit evaluation of whether features shared by organisms are
>uniquely shared or part of a primitive suite of features.  In jargon -- the
>explicit rejection of plesiomorphic characters in the evaluation
>of phylogeny.

Myself, I think there are three elements that are essentially cladistic.
The first is an idea are about the goals of systematics: that its sole aim,
as Bob has once put it, is "telling the tree". Of course I agree with
Toomey that one of the aims of taxonomy since Darwin has been to
reconstruct evolutionary history, but that aim has been mixed up with all
sorts of other issues; for example about the degree and kinds of divergence
necessary to warrant a valid use of higher taxonomic categories. I take it
that one of the basic lessons of cladism is that, for example, the various
debates about when in human evolution true hominids appeared are wastes of
time. I realize that many pre-cladistic systematicists were somewhat
sceptical about the status of higher taxonomic units, but in my view its
the cladists who really rammed this home. The second is the methodological
idea that Toomey I think is right to emphasize: that characters that are
primative to a group can tell you nothing about relations within that
group. Third, I think there is a metaphysical idea: that only monophyletic
chunks of the tree are biologically real entities. I doubt whether all this
has to be a package deal; in particular, one could clearly accept the
methodological moral about the reconstruction of history whilst accepting
the biological reality of some non-monophyletic chunks of that tree.

Kim Sterelny, Philosophy,
Victoria University of Wellington, New Zealand

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