Mary P. Winsor

Non-essentialist methods in pre-Darwinian taxonomy

The current widespread belief that taxonomic methods used before Darwin were essentialist is ill-founded. The essentialist method developed by followers of Plato and Aristotle required definitions to state properties that are always present. Polythetic groups do not obey that requirement, whatever may have been the ontological beliefs of the taxonomist recognizing such groups. Two distinct methods of forming higher taxa, by chaining and by examplar, were widely used in the period between Linnaeus and Darwin, and both generated polythetic groups. Philosopher William Whewell congratulated pre-Darwinian taxonomists for not adhering to the rigid ideal of definition used in the mathematical sciences. What he called the “method of types” is here called the “method of exemplars” because typology has been equated with essentialism, whereas the use of a type species as the reference point or prototype for a higher category was a practice inconsistent with essentialism. The story that the essentialism of philosophers dominated the development of systematics may prove to be a myth.

Cain on Linnaeus: the scientist-historian as unanalysed entity

Abstract Zoologist A. J. Cain began historical research on Linnaeus in 1956 in connection with his dissatisfaction over the standard taxonomic hierarchy and the rules of binomial nomenclature. His famous 1958 paper ‘Logic and Memory in Linnaeuss System of Taxonomy’ argues that Linnaeus was following Aristotles method of logical division without appreciating that it properly applies only to ‘analysed entities’ such as geometric figures whose essential nature is already fully known. The essence of living things being unanalysed, there is no basis on which to choose the right characters to define a genus nor on which to differentiate species. Yet Cains understanding of Aristotle, which depended on a 1916 text by H. W. B. Joseph, was fatally flawed. In the 1990s Cain devoted himself to further historical study and softened his verdict on Linnaeus, praising his empiricism. The idea that Linnaeus was applying an ancient and inappropriate method cries out for fresh study and revision.

Considering affinity: an ethereal conversation (part two of three).

In 1840 Hugh Strickland published a diagram showing the relationships of genera of birds in the kingfisher family. Three years later he applied this mapping idea to genera of birds of prey and songbirds, creating a large wall chart that he displayed to colleagues but never published. Both of his diagrams featured a scale of degrees of affinity. The meaning of taxonomic affinity was something Darwin thought about deeply. Details in the chart undermine Stricklands claim that his method was purely inductive.