BIC wrote:

"Could it really be that the rest of the phylogenetics world has no grounds for considering paraphyly as a peril to classification? Is it truly possible that the rejection of paraphyly is only about fashion? Those are a lot of independent thinking scientists you disparage with that statement. Instead of the Galileo analogy you use, I suggest the analogy of the Flat Earth Society or believers in alien abduction."



Me:

If paraphyletic taxa are a "peril to classification," then I fail entirely to see what that "peril" may be. As R.L. Carroll pointed out, paraphyletic groups are the inevitable result of the process of evolution. Unless one is opposed to the very idea of evolution, paraphyletic taxa should never be a "peril" to biological classification, which must of course conform to the facts known to science as evolution. The rejection of paraphyletic taxa by Hennig is not of course "fashion." After all, he was alone when he formulated his principle of holophyly. The rest of the biological community had no problem with paraphyletic taxa, such as Reptilia. Since Darwin argued that birds evolved from a reptile, he of course knew that Reptilia does NOT include all of the descendants of the common ancestor of the reptiles. Darwin, therefore, knew that Reptilia was "paraphyletic" sensu Hennig, but he apparently never lost any sleep over it. The rest of the scientific community knew that Reptilia was "paraphyletic" ever since the discovery of Archaeopteryx, and yet no one was bothered by that fact until Hennig came along and declared paraphyletic taxa unacceptable.



So, you misunderstand. It is merely fashionable for many systematists to blindly follow Hennig's principle of holophyly by rejecting paraphyletic taxa, not that there is any scientific justification for disqualifying paraphyletic taxa.



Yes there are many independent thinkers among scientists, but the majority of the cladists are not among them. There are indeed a few independent thinkers among the cladists, and they tolerated paraphyletic taxa, but these cladists are viewed with suspicion by other, more orthodox cladists.



BIC:

But you also may find that social issues aside, the bottom line for the acceptance of new ideas is the continued failure to reject the new ideas.



Me:

If there is any continued failure, it is the cladists' failure to see that some of their ideas, such as their intolerance of paraphyletic taxa, are scientifically untenable. Further, it appears that some cladists are beginning to soften their irrational, hard line stance against paraphyletic taxa. For example, the family Agamidae, which was once disqualified because it was thought to be paraphyletic, is now being recognized by the very cladists who had lumped it into the same family as the Chamaeleonidae more than a decade ago.

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