philosophical conjectures and their refutation sir karl popper is well known for explicating science in falsificationist terms for which his degree of corroboration formalism cheb has become little more than a symbol for example de queiroz and poe in this issue argue that cheb reduces to a single relative conditional probability pehb the likelihood of evidence e given both hypothesis h and background knowledge b and in reaching that conclusion without stating or expressing it they render popper a verificationist the contradiction they impose is easily explainedde queiroz and poe fail to take account of the fact that popper derived cheb from absolute logical probability and severity of test sehb where critical evidence peb is fundamental thus de queiroz and poes conjecture that pehb cheb is refuted falsificationism not verificationism remains a fair description of the parsimony method of inference used in phylogenetic systematics not withstanding de queiroz and poes mistaken understanding that statistical probability justifies that method although de queiroz and poe assert that maximum likelihood has the power to explain data they do not successfully demonstrate how causal explanation is achieved or what it is that is being explained this is not surprising bearing in mind that what is assumed about character evolution in the accompanying likelihood model m cannot then be explained by the results of a maximum likelihood analysis