Popperian falsificationism

The central tenets of the falsificationist philosophy of Karl R. Popper are reviewed in detail, and the way they do or do not apply to systematics and phylogeny reconstruction is analyzed. Cladistic analysis, cast in either maximum parsimony or in maximum likelihood approaches, is not compatible with Popperian falsificationism. The main reasons are the absence of a deductive link between a hypothesis of phylogenetic relationships and character distribution on a tree, which translates into the absence of the basic asymmetry of falsification versus verification. This sets Popper s philosophy of science apart from inductive systems. In cladistic analysis, falsification (disconfirmation) is symmetrical to verification (confirmation), which reveals an inductive and hence probabilistic background. The basic problem of systematics as an empirical science resides in character conceptualization and its critical evaluation. 

Popper not only insisted on simple language he also insisted on rationality as the basis for argumentation. To him the rationalist tradition . .. is the tradition of critical discussion — not for its own sake, but in the interest of the search for truth (Popper, 1989 101), truth in this context meaning a regulative principle only (see also Appendix II). Popper equated rationality with the critical attitude. .. (Popper, 1989 248). Given Popper s broad impact on natural sciences and scientists, most systematists probably strive to adopt a critical attitude, a culture of critical discussion, which in a sense represents a weak form of Popper s falsificationism. In that broad sense, modern systematics is — hopefully — Popperian. 

The claim conld be made that systematics can proceed without underlying universal laws, for what is reqnired is nothing bnt a method that allows us to choose a preferred hypothesis from a set of competing hypotheses of relationships relative to some theory such as evolutionary theory. Indeed, we do have a method at our disposal that allows us to do just this, but is it Popperian in its logic The conformity of parsimony analysis with Popper s falsificationism has been asserted in terms of Popper s concepts of logical probability, explanatory power, degrees of corroboration and severity of test. Let us look at these concepts in more detail. 

Comment In Popperian falsificationism, knowledge of the empirical world requires a deductive link between a theory and a singular statement that can be related to an observable state of affairs, given initial conditions. The statement Species are a part of the empirical world requires a (ostensive) concept of species that can be applied to an empirical base (Korner, 1959). Since the attachment of an ostensive concept to an empirical base occurs here and now (hie et nunc), the only ostensive species concept is Mayr s nondimensional species concept (Mayr, 1982). The phylogenetic species concept is a nonostensive concept. 

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