johnscanlon wrote:

"First the appeal to inclusivity and tolerance, including the remarkable statement that pheneticists are entitled to their beliefs. Anybody who still thinks that grouping by similarity is the best method of inferring phylogeny (tree-building) is simply mistaken in their belief. Tolerance can be taken too far."

Pheneticists hold the viewpoint that phylogenetic history is unknowable. Since history cannot be observed, it must therefore be inferred, as G. G. Simpson pointed out. The pheneticists therefore are correct to the extent that phylogenetic history cannot be determined with absolute certainty. Because of this belief, to which they are entitled, they thought that the best indicator of relationship would be overall similarity. Hence they have developed an elaborate set of mathematical techniques for measuring and quantifying morphological similarity. Pheneticists are simply not interested in building phylogenetic trees. Their phenogram simply tells us which species are morphologically most similar to each other. In some cases, overall similarity does work. For example, the common chimp is the closest relative of the pygmy chimp according to gestalt. In other cases, in which the rate of morphological evolution is different, this method does not work. For example, in terms of overall (morphological) similarity, Pan clusters with Gorilla, not Homo. But of course we know that Pan is actually closer to Homo phylogenetically than it is to Gorilla. The phenetic method therefore does have its merit and uses, although it is not infallible. In fact, it is sometimes more reliable than cladistic methodology since gestalt is sometimes better evidence for a close relationship than the one or a few characters with which the cladists may anchor a particular node in a cladogram.

Although the pheneticists are entitled to their believes, they are not entitled to impose their believes on others. Pheneticism has suffered a drastic decline, perhaps because it has now been shown that the pheneticists' fundamental belief (that phylogenetic history is unknowable) has now been all but falsified.

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