Functional and Evolutionary Explanations in Morphology

Abstract

Two partly overlapping dichotomous systems of explanations exist in morphology, namely: (a) nomological-deductive versus historical-narrative explanations; and, (b) functional versus evolutionary. Evolutionary explanations cause the partial overlap between these systems as they can be either nomological-deductive or historical-narrative depending on the particular conclusion being advocated. Complete or full explanations must include both parts of either dichotomy, but this is not possible in many instances. Most explanations in morphology are functional ones, but, although incomplete, these are perfectly sensible and usable contrary to the claims of some evolutionists. Historical evolutionary explanations must be established on prior nomological functional explanations, but this has not been done in many discussion of the evolutionary history of morphological features in comparative anatomical and paleontological texts. Unfortunately such historical, morphological explanations, no matter how ingenious they may be, are vacuous. Moreover, excellent functional explanations in morphology do not automatically lead to correct historical evolutionary explanations. What is needed in morphology is the proper blend of functional and historical evolutionary explanations to arrive at persuasive full explanations. With this broad-based approach, a true evolutionary morphology will emerge with great advances in derived phylogenetic and classificatory analyses.