paraphyly

[SKALA Zdenek]

Larissa Vasilyeva:
>paraphyly is real only from EXTENSIONAL perspective (contents of taxa),
while INTENSIONALLY (character 
>aspect) paraphyly is mistake (meaning of terms: Buck, Hull, 1966). 

This distinction fails to be general; in a case of clades with (partly)
homoplastic synapomorphies and/or reversals are even holophyletic taxa
defined extensionally. At the same time, the Buck&Hull's distinction
depends on a very specific concept of intensionality (in short, the
unary operator "non" is not considered class-defining attribute).
Zdenek Skala
skala at incoma.cz