Hennig XVIII

John Grehan jrg13 at PSU.EDU
Wed May 12 21:01:12 CDT 1999

The ensuing discussion following my question about the position of
Rosa gives the impression that the situation at leasts warrant's
critical appraisal - something that I do not believe cladistic theorists or
have addressed (but I am open to correction here).

I recall a statement from an email correspondent that Hennig was in Italy
 during WWII. If correct this would certainly be suggestive given that
there are not only "similarities" between Hennig and Rosa, but also
apparently some duplication according to Croizat.

I think Hull (1988) makes a case for reconizing only direct influences
between founder and follower (my words), but Robin Craw in a recent
paper (citation not in hand at this moment) argued that there was a
matrix or network of influences and effects surrounding the history of
cladistics so that no single person could be regarded as the primary
or sole source (if I have paraphrased his paper correctly from memory).

Given what is known about the history of cladistic approaches I would
think that Hennig might be considered as the founder of what might
be loosely called a "Hennigian" school or tradition (I would include
explicitly Hennigian as well as transform cladists here). In terms of
theoretical development I would be inclined towards Colocino's view
that Rosa deserves merit as a central figure at least as important
as Hennig.

Tom DiBenedetto states that Rosa's work did not find widespread
acceptance - but with the widespread acceptance of cladistics it
would seem that his work has - even if by proxy. The statement that
Rosa's  formulations do not lie at the core of most (any?) cladists
 view of their science I would have to request greater clarification.
Since Rosa is clearly a cladist, his formulations were cladistics, so
those who support cladistic modes of analysis (and I would have to
include myself) have Rosa's theory at their core.

John Grehan

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