Thomas Aquinas describes embryological development as a succession of vital principles, souls, or substantial forms of which the last places the developing being in its own species. In the case of human beings this form is the rational soul. Aquinas' well-known commitment to the view that there is only one substantial form for each composite and that a substantial form directly informs prime matter leads to the conclusion that the succession of soul kinds is non-cumulative. The problem is that this (...) view seems to entail discontinuity in the process of generation. Aquinas argues for the continuity of a conceived being by appealing to the teleological argument at the core of Aristotle's embryogenesis theory: according to Aristotle, embryonic development is a gradual actualization of the form of the species, potentially present in the embryo from the outset. Aquinas denies such a gradualist account due to his metaphysical commitments , arguing instead that the .. (shrink)

Despite the renewed interest in Aristotle’s Generation of Animals in recent years, the subject matter of GA V, its preferred mode(s) of explanation, and its place in the treatise as a whole remain misunderstood. Scholars focus on GA I-IV, which explain animal generation in terms of efficient-final causation, but dismiss GA V as a mere appendix, thinking it to concern (a) individual, accidental differences among animals, which are (b) purely materially necessitated, and (c) are only tangentially related to the topics (...) discussed in the earlier books. In this paper, we defend an alternative and more integrated account of GA V by closely examining Aristotle’s methodological introduction in GA V.1 778a16-b19 and his teleological explanation of the differences of teeth in GA V.8. We argue for the unity of both GA V and of GA as a whole and present a more nuanced theory of teleological explanation in Aristotle’s biology. (shrink)

Debates on the moral status of human embryos have been highly and continuously controversial. For many, these controversies have turned into a fruitless scholastical endeavor. However, recent developments and insights in cellular biology have cast further doubt on one of the core points of dissent: the argument from potentiality. In this article we want to show in a nonscholastical way why this argument cannot possibly survive. Getting once more into the intricacies of status debates is a must in our eyes. (...) Not merely intellectual coherence but the standing and self-understanding of current stem cell research might profit from finally taking leave of the argument from potentiality. (shrink)

L’objectif de cette étude est d’examiner l’hypothèse selon laquelle la quarta natura, théorisée par Épicure pour rendre compte des activités de l’âme et décrite par Lucrèce (DRN III, 237-244), résulte de l’appropriation par Épicure d’un argument aristotélicien afin de répondre aux critiques d’Aristote à l’égard de la théorie démocritéenne de l’âme. Pour ce faire, on analysera le témoignage de Cicéron (Tusc. I, 10, 22) sur le quintum genus attribué à Aristote et on rendra compte des débats sur ses sources possibles. (...) En confrontant le témoignage cicéronien avec les vers dans lesquels Lucrèce expose la théorie de la quatrième nature, on montrera les fortes ressemblances entre leurs structures argumentatives. Sur la base de la possible datation de la théorie de la quintessence et de son attribution au Péripatos du iie siècle av. J-C, on proposera d’expliquer cette similarité par l’appropriation par Lucrèce de l’argument par soustraction qui caractérise la théorie de la quintessence, à partir de laquelle il aurait conçu la théorie de la quatrième nature. Afin de vérifier l’exactitude de cette interprétation, on examinera l’hypothèse selon laquelle l’appropriation de cet argument, et donc la conception de la quatrième nature, remontent à Épicure, la paternité de l’argument par soustraction (à partir duquel les péripatéticiens postérieurs pourraient avoir conçu la théorie de la quintessence) étant alors à attribuer à Aristote. Pour ce faire, on analysera un passage du De Caelo (269a30-269b2) et un passage de La Génération des animaux (736b29-737a1) où l’argument par soustraction sert à introduire d’une part l’éther et d’autre par le pneuma. Ensuite, en s’appuyant sur l’analyse d’un passage du De Anima (405a5-7), on montrera que l’appropriation de cet argument pourrait s’expliquer par la tentative, de la part d’Épicure, de répondre à une critique aristotélicienne concernant la théorie démocritéenne de l’âme. (shrink)

Aristotle’s soul is a first principle (an ‘efficient cause’) of every vital change in an animal, in the way that a craft is a cause of its product’s coming-to-be. We argue that the soul’s causal efficacy cannot therefore be reduced to the formal constitution of vital phenomena, or to discrete interventions into independently constituted processes, but involves the exercise of vital powers. This reading does better justice to Aristotle’s conception of craft as a rational productive disposition; and it captures the (...) soul’s continuous causal role as that which brings about all forms of vital change and underwrites their unity. (shrink)