ABSTRACT
Chapter 4 began with the presentation and a short discussion of an important topic concerning a priori versus a posteriori explanations in evolutionary biology, which has been referenced several times throughout this book. As explained in that Chapter, this controversial issue can be broadly summarised as follows. Some authors, following the basic guidelines of the cladistic paradigm, hold that evolutionary explanations should be based on comprehensive, explicit phylogenetic cladograms, and not, as done by some 'functional evolutionary morphologists' sensu Cracraft, 1981, be a priori to, or irrespective of, phylogenetic comparisons. The latter hold that homoplasic characters should in some way be detected and removed a priori to the phylogenetic analysis, and usually formulate major evolutionary explanations, such as those concerning the evolution of certain complex systems or the reconstruction of potential 'ancestral forms', a priori to the phylogenetic comparison. As emphasised in the present work, such a priori evolutionary explanations rely necessarily on more or less ad hoc stories, with this being particularly true for those concerning homoplasy or character evolution, which are 'ad libitum explanations, capable of explaining patterns and non-patterns alike and, in being able to do so ,..., explain nothing at all' (Kludge, 2001: 202).
