A/The Brief History of Three-Taxon Analysis

Recent claims by its advocates notwithstanding, three-taxon analysis (3ta) provides no method for recognizing reversals or for applying them as apomorphies. Accordingly, 3ta could be used as a phylogenetic method only under an assumption of irreversibility. Being a method for calculating trees from character data, 3ta is not connected to any particular rule ("interpretation") for selecting resolutions of consensus trees considered as abstract diagrams. 3ta cannot be justified simply by invoking a general minimization principle such as Occam's Razor, since that would cover almost any method. Some more specific basis is needed, and consideration of proposed bases for 3ta shows that none is even remotely adequate.