The longstanding species problem in biology has a history that suggests a solution, and that history is not the received history found in many texts written by biologists or philosophers. The notion of species as the division into subordinate groups of any generic predicate was the staple of logic from Aristotle through the middle ages until quite recently. However, the biological species concept during the same period was at first subtly and then overtly different. Unlike the logic sense, which relied (...) on definitions of the essence of both genus and species, biological species from the time of Epicurus were consistently considered to involve a reproductive element: in short, living species relied not on essential definitions, but on the generative cause, which might not be definable. I term this the generative conception of species: species were the generation by reproduction of form. This undercuts the claim that species before Darwin were essentialist, and divorces the notion of a type from that of essence. In fact, as late as the end of the nineteenth century, logicians explicitly treated biological “species” as a homonym only of logical essentialist species, and permitted considerable deviation from the type or form. At every point, species in logic were thought to be a subset, in effect, of some more general notion. I sketch a history of both philosophical and biological traditions of the species concept, before turning to the current conceptions. These are reconsidered in the light of this history, and in particular Mayr’s changing views are shown to be somewhat Whiggish, historiographically. Of the many touted biological species concepts, only one of which (Mayr’s) is called _the_ Biological Species Concept, none appears to capture all the relevant facts, intuitions, and operational requirements of biology. Cladistic conceptions, however, have much in common with the older philosophical literature, in that the natural group of cladism is the clade, or monophyletic group. After considering the Individuality Thesis, and the metaphysics of species, we see that species are the most particular terminal taxa in a clade, and that they are “defined” in terms of the particular synapomorphies, or evolved characters, that are causally responsible for keeping the lineages that organisms form distinct from one another. In this way, we can remain within the generative conception of species that has been in play for over two millennia, and yet avoid the pitfalls of prior attempts to find a universal conception of species. (shrink)

Le texte suivant s'appuie assez largement sur des informations scientifiques de la biologie végétale. Ce choix de philosopher à partir de la technicité et de l'historicité des objets botaniques correspond à un parti pris. La proximité de l’humain à ses objets d’étude, sa tendance à anthropomorphiser, voire anthropocentrer, les observations ou les problèmes qui se présentent à lui, a fait l’objet de multiples réflexions philosophiques et épistémologiques. Kant, pour qui « tout intérêt est finalement pratique [...] même celui de la (...) raison spéculative n’est que conditionné et n’est complet que dans l’usage pratique » 1 , Bachelard, qui appelle à « substituer à la notion anthropomorphe de cause la notion scientifique de fonction » 2 , ou Canguilhem pour qui « l’anthropocentrisme est plus aisé à rejeter que l’anthropomorphisme [...] Peut-on être biologistes sans se sentir du côté des vivants ? » 3 . Ces réflexions ne sont-elles pas toujours centrées sur les modes de connaissance ou de pensée de l’humain, alors que les « objets d’étude » en question demeurent souvent dans un certain flou, voire une large indétermination ? La démarche suivie ici tente d’aller dans une autre direction. Elle interroge les effets de l’anthropocentrisation d’objets spécifiques à la biologie végétale, envisagée aussi bien dans sa profondeur historique que dans ses développements techniques récents. Nous tentons ici un pari : une analyse précise de nos connaissances botaniques, actuelles et passées, peut nourrir la réflexion philosophique sur notre rapport aux plantes et, à travers elles, sur nous-mêmes. (shrink)