The essentialism story is a version of the history of biological classification that was fabricated between 1953 and 1968 by Ernst Mayr, who combined contributions from Arthur Cain and David Hull with his own grudge against Plato. It portrays pre-Darwinian taxonomists as caught in the grip of an ancient philosophy called essentialism, from which they were not released until Charles Darwin's 1859 Origin of Species. Mayr's motive was to promote the Modern Synthesis in opposition to the typology of idealist morphologists; (...) demonizing Plato served this end. Arthur Cain's picture of Linnaeus as a follower of 'Aristotelian' (scholastic) logic was woven into the story, along with David Hull's application of Karl Popper's term, 'essentialism', which Mayr accepted in 1968 as a synonym for what he had called 'typological thinking'. Although Mayr also pointed out the importance of empiricism in the history of taxonomy, the essentialism story still dominates the secondary literature. The history of the first telling of the essentialism story exposes its scant basis in fact. (shrink)

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. (shrink)

Reading the Shape of Nature vividly recounts the turbulent early history of the Museum of Comparative Zoology at Harvard and the contrasting careers of its founder Louis Agassiz and his son Alexander. Through the story of this institution and the individuals who formed it, Mary P. Winsor explores the conflicting forces that shaped systematics in the second half of the nineteenth century. Debates over the philosophical foundations of classification, details of taxonomic research, the young institution's financial struggles, and the personalities (...) of the men most deeply involved are all brought to life. In 1859, Louis Agassiz established the Museum of Comparative Zoology to house research on the ideal types that he believed were embodied in all living forms. Agassiz's vision arose from his insistence that the order inherent in the diversity of life reflected divine creation, not organic evolution. But the mortar of the new museum had scarcely dried when Darwin's Origin was published. By Louis Agassiz's death in 1873, even his former students, including his son Alexander, had defected to the evolutionist camp. Alexander, a self-made millionaire, succeeded his father as director and introduced a significantly different agenda for the museum. To trace Louis and Alexander's arguments and the style of science they established at the museum, Winsor uses many fascinating examples that even zoologists may find unfamiliar. The locus of all this activity, the museum building itself, tells its own story through a wonderful series of archival photographs. (shrink)

The current picture of the history of taxonomy incorporates A. J. Cain's claim that Linnaeus strove to apply the logical method of definition taught by medieval followers of Aristotle. Cain's argument does not stand up to critical examination. Contrary to some published statements, there is no evidence that Linnaeus ever studied logic. His use of the words “genus” and “species” ruined the meaning they had in logic, and “essential” meant to him merely “taxonomically useful.” The essentialism story, a narrative that (...) has most pre-Darwinian biologists steeped in the world view of Plato and Aristotle, is ill-founded and improbable. (shrink)

Between 1937 and 1940 the Taxonomic Principles Committee of the newly-founded Association for the Study of Systematics in Relation to General Biology (later the Systematics Association) attempted to define the relationship between evolution and taxonomy. The people who took part in the discussion were W.T. Calman, C.R.P. Diver, J.S.L. Gilmour, J.S. Huxley, W.D. Lang, J.R. Norman, R. Melville, O.W. Richards, M.A. Smith, T.A. Sprague, H. Hamshaw Thomas, W.B. Turrill, B.P. Uvarov, A.F. Watkins, E.I. White, and A.J. Wilmott. Most of the (...) botanists asserted that taxonomy was a practical matter to be kept distinct from phylogenetic speculation, and most of the zoologists insisted that taxonomists must strive to represent evolution if they wished to be scientific. The disagreement seemed to be hardening rather than approaching compromise when World War Two stopped the committee's work. (shrink)

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 Linnaeus's System of Taxonomy’ argues that Linnaeus was following Aristotle's 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 Cain's 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. (shrink)

Thomas Henry Huxley and Charles Darwin discovered in 1857 that they had a fundamental disagreement about biological classification. Darwin believed that the natural system should express genealogy while Huxley insisted that classification must stand on its own basis, independent of evolution. Darwin used human races as a model for his view. This private and long-forgotten dispute exposes important divisions within Victorian biology. Huxley, trained in physiology and anatomy, was a professional biologist while Darwin was a gentleman naturalist. Huxley agreed with (...) John Stuart Mill's rejection of William Whewell's sympathy for Linnaeus. The naturalists William Sharp Macleay, Hugh Strickland, and George Waterhouse worked to distinguish two kinds of relationship, affinity and analogy. Darwin believed that his theory could explain the difference. Richard Owen introduced the distinction between homology and analogy to anatomists, but the word homology did not enter Darwin's vocabulary until 1848, when he used the morphological concept of archetype in his work on Cirripedia. Huxley dropped the word archetype when Richard Owen linked it to Plato's ideal forms, replacing it with common plan. When Darwin wrote in the Origin of Species that the word plan gives no explanation, he may have had Huxley in mind. Darwin's preposterous story in the Origin about a bear giving birth to a kangaroo, which he dropped in the second edition, was in fact aimed at Huxley. (shrink)

Early in this century, only a few biologists accepted that natural selection was the chief cause of evolution, until the independent calculations of John Burdon Sanderson Haldane (1892–1964), Sewall Wright and R. A. Fisher demonstrated that ideal populations subject to Mendel's laws could behave as Darwin had said they would. Evolutionary theorist John Maynard Smith, a student of Haldane's, has raised the question of why Haldane, who was no naturalist, took up the subject of evolution, and he suggests that the (...) answer may have to do with Haldane's lively interest in religion. In fact Maynard Smith's answer has much more evidence in its favour than he knew. (shrink)

Species that died without leaving descendants Darwin called ‘utterly extinct’. They far outnumber the ancestors of all living things, so they resemble the dark matter of modern cosmology, which far outweighs visible matter. He realized in 1837 that their absence is what creates the groups in a natural classification. In his Notebook B he combined the idea that species multiply with the idea that ancestors' relatives must mostly be extinct. The fossil Megatherium was utterly extinct. The iconic branching ‘I think’ (...) diagram shows extinction causing the origin of genera by eliminating intermediate species. Darwin’s concept of taxonomic ranks, starting with the genus, was informed by his interaction with taxonomists. Based on his familiarity with demography, Darwin reasoned that the survival of transitional forms was unlikely, which helped him decide to focus at the species level. When drafting his theory in the 1840s, he left out these speculative ideas, but they emerged again in the 1850s when he realized his theory needed a cause for branches to diverge. His ecological answer worked at the species level, but his Principle of Divergence was unconvincing at higher taxonomic levels. In the Origin, Darwin repeatedly insisted on the importance of utter extinction. (shrink)

Carl Becker's classic 1931 address "Everyman his own historian" holds lessons for historians of science today. Like the professional historians he spoke to, we are content to display the Ivory- Tower Syndrome, writing scholarly treatises only for one another, disdaining both the general reader and our natural readership, scientists. Following his rhetoric, I argue that scientists are well aware of their own historicity, and would be interested in lively and balanced histories of science. It is ironic that the very professionalism (...) that ought to equip us to write such histories has imposed on us a powerful taboo that renders us unable to do so. We who count ourselves sophisticated in describing the effects of social forces upon past scientists have been remarkably unconscious of the ways our own practices are being shaped by our need to distinguish ourselves from scientists who write history. Our fear of presentism in general and Whig history in particular is really a taboo, that is, an excessive avoidance enforced by social pressure. It succeeds at making our work distinct from histories written by scientists, but at the awful cost of blotting out the great fact of scientific progress. Scientists may be misguided in expecting us to celebrate great men, but they are right to demand from historians an analysis of the process of testing and improvement that is central to science. If progress in general is a problematic term, we could label the process "emendation.". (shrink)

The word ``deme'' was coined by the botanists J.S.L. Gilmour and J.W.Gregor in 1939, following the pattern of J.S. Huxley's ``cline''. Its purposewas not only to rationalize the plethora of terms describing chromosomaland genetic variation, but also to reduce hostility between traditionaltaxonomists and researchers on evolution, who sometimes scorned eachother's understanding of species. A multi-layered system of compoundterms based on deme was published by Gilmour and J. Heslop-Harrison in1954 but not widely used. Deme was adopted with a modified meaning byzoologists (...) leading the evolutionary synthesis – Huxley, Simpson, Wright,and Mayr. Connections are shown between Gilmour's ideas around definingthe deme, his role in founding the Systematics Association, and his chapter``Taxonomy and Philosophy'' in the book The New Systematics. Thishistorical episode raises questions about the role of carefully-definedwords in scientific practice. (shrink)