The principle of parsimony and how August Weismann used it

Resumen

ABSTRACT. This paper explores the use of the principle of simplicity in August Weismann’s critiques of the inheritance of acquired characters. After considering different accounts of simplicity as a scientific virtue to be taken into account in science evaluation, the paper goes on to scrutinize a particular example of the principle of parsimony at work. The author considers the structure of August Weismann’s arguments for the all-sufficiency principle of natural selection (NS) to conclude that a variety of lines of reasoning can be identified in his account and that parsimony plays a different role to each. There has been a long-lasting agreement among historians of biology and philosophers of science alike that the work of Weismann signals that theories involving the heredity of acquired traits are flawed, as such type of inheritance is not possible in evolution.

  While much debate has recently arisen in the domain of evolutionary developmental biology challenging the Weismann barrier principle, both the proponents of the “extended synthesis” and the Neodarwinian orthodoxy seem to coincide in that Weismann’s arguments favor NS to the virtual exclusion of any other principle regulating the transmission of traits in evolution. Whatever Weismann would have wanted to conclude, I will argue that this understanding of what Weismann’s arguments entail is a mistake.

KEY WORDS. Extended synthesis, Lamarckian inheritance, natural selection, parsimony, philosophy of biology.