I see that many web surfers reach this blog by searching for “the difference between cladistics and phenetics”. I guess the reason is that this difference is what cladistics love to use to contrast its class-realism (ie, search for “natural groups”) against approaches that are nominalistic (ie, eiher understand that such “natural groups” are ulimately paradoxically contradictory or simply don’t believe in them). This lumps rationality (ie, nominalism) with disbelief in evolution, thereby leaving cladistics as the only phylogenetic approach.
However, understanding that such “natural groups” are ulimately paradoxically contradictory is not the same objection to cladistics as disbelief in evolution is. The understanding simply denies cladistics’ assumption that there is “a single true tree of life”, whereas the disbelief denies the idea of evolution. Between cladists and disbelievers in evolution is actually the rational position: to accept evolution but deny that evolution can be described both consistently and unambiguously at the same time, which is called evolutionary taxonomy. Evolutionary taxonomy is thus both phenetic and phylogenetic by accepting an evolutionary context, but at the same time understanding that this context can’t be both consistently and unambiguously described at the same time. We can be consistent and we can be unambiguous, but we can’t be both consistent and unambiguous at the same time. Consistency simply excludes unambiguity, and vice versa, on the contrary to what cladistics assumes as an axiom (and moreover defines).