Hypothesis ad hoc auxiliary

The use of parsimony thus results in three separate yet closely inter-related issues (1) the general nature of parsimony and its status in Popper s philosophy of science, (2) the role that parsimony and ensuing ad hoc auxiliary hypotheses of homoplasy play in safeguarding the (logically subordinated) hierarchy from failing as it is applied to the world of experience, and (3) the role of parsimony in the putative falsification of alternative hierarchies that stand for alternative hypotheses of phylogenetic relationships. This section will deal with the first two of these issues the third will be dealt with in the next section. 

Whereas parsimony certainly allows us to find the cladogram that minimizes incongruence, it is based on the very general scientific principle of economy of hypotheses, which can be traced back to William Ockham. Popper (1979 214ff) certainly agrees that scientific explanations should in every case minimize ad hoc auxiliary hypotheses. Indeed, it is exclusively with respect to this principle of minimizing auxiliary hypotheses — whether ad... 

In one sense, however, Popper specifically rejected the use of ad hoc auxiliary hypotheses, by adopting a strategy used to immunize a theory from falsification. Popper (1979 185-186) illustrated this strategy using a simple syllogism. 

The liberty to shift from assumed homology to assumed homoplasy and vice versa amounts to the use of ad hoc auxiliary hypotheses in an immunizing strategy that protects... 

Lakatos needs a critical evaluation of theories in his system just as much as Popper, and just like Popper he did not allow ad hoc auxiliary hypotheses that are not independently testable to distort such critical evaluation of competing theories. Both Lakatos and Popper understood hypotheses in the sense of universal propositions and both employed the modus tollens form of argument. Whether the emphasis is on corroboration or falsification, this very distinction cannot be had outside Popper s solution to the logical problem of induction, for it only can provide that very asymmetry, and hence the basis on which to distinguish falsificationism from verificationism. ... 

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