There are two orthogonal approaches in phylogenetics: evolutionary taxonomy and cladistics.( Orthogonal means diametrically opposed). They represent the two possible orthogonal approaches to reality: objectivity respectively subjectivity. The reason that they have clashed in phylogenetics as equals is that phylogenetics is half concrete (i.e., in dealing with existing living objects) and half abstract (i.e., in dealing with the class biological species and a model of their origin).
It means that phylogenetics has turned into a battle field between objectivists – sticking to objects, empirical facts and falsification, on one side, and subjectivists – sticking to classes, a feeling of “natural” and optimization, on the other side (of course also containing intermediates that do not understand the orthogonality between these two approaches). The main battle between the two approaches took place in the 1970-ies, resulting in that the subjectivists won. Phylogenetics is thus the first scientific discipline ever wherein the question of whether it shall rest on an objective or subjective approach (and thus whether it shall comply with empirical facts or not) has been decided democratically, that is, by a majority decision, and the result was that subjectivity won (that is, that it shall not comply with empirical facts).
What this democratic decision means is extremely interesting in many aspects. One is whether we can decide democratically whether we shall comply with empirical facts (like that time is relative) or not? Can we vote away facts? Another is whether all phylogeneticists have to comply with this decision, i.e., to not comply with empirical facts, or not? Does the decision mean that phylogeneticists have to deny facts? Yet another is whether the decision can turn subjectivity’s erroneous assumption that a single truth can be reached by optimization into being correct? Can we change facts by democratic (i.e., majority) decisions?
I once conveyed the in science generically accepted argument that “the only truths we can arrive to are statements that are not falsified (i.e., that are corroborated) by empirical facts” to the cladist Mikael Härlin. He replied that it was the most ridiculous and narrow-minded view on truths he had ever heard. Clear is thus that cladists (i.e., subjectivists) have a looser definition of the concept truth than objectivists have. Exactly what it is is not clear, although it is clear that it does not necessarily comply with empirical facts. From the writings of Mikael, I do, however, think that the definition is what Kuhn expressed as “anything goes”. Kuhn did not, however, clarify how “truths” that conflict with empirical facts shall be treated. What does, for example, the truth that time is absolute (i.e., not relative) mean? Is time relative or absolute? I have asked Mikael to answer this question in public, but he refuses to, instead withdrawing into the protection (i.e., the cave) of his institution.
The present situation in phylogenetics is thus that it denies empirical facts and think that what is impossible is possible. It has actually decided by democratic voting that it is so. It has thus decided by consensus that the Emperor has clothes, although anyone with a clear mind can see that he hasn’t. (It has even explicitly waived fare-well to objectivity by Fredrik Pleijel). Evolutionary taxonomy is thus down, but not out. The battle will continue independently of present consensus. Opinions that are not founded on facts change per definition, and sooner or later the opinion that scientific opinions must be founded on facts has to win. Anything does not go. Kuhn was wrong.