Giardina, G: Fisica del movimento e teoria dell'infinito

predecessori: ne risulta che per Aristotele quello di apeiron è un concetto tanto inevitabile per la comprensione del tempo, delle quantità continue, dello stesso movimento (sullo sfondo stanno i paradossi di Zenone), quanto aporetico se l'infinito viene concepito come sostanza o corpo.Queste osservazioni non rendono minimamente conto della ricchezza di contenuti del lavoro di Giardina, che resterà come un contributo indispensabile alla comprensione 'fine' di alcune fra le più complesse pagine della Fisica aristotelica. (Mario Vegetti)***With this work on the problems of motion and infinity in the third book of Aristotle's Physics, Giovanna R. Giardina follows up on her previous commentaries on book I (the issue of principles) in 2002, and book II (the issue of causes) in 2006. I say commentary because the author's exegetical style approaches the text in great detail, discussing textual, semantic and, of course, conceptual problems, and makes regular use of an assiduous review, on one hand, of the tradition of the Commentators, from Alexander to Simplicius and Philoponus up to Thomas, and, on the other hand, of the critical literature (the book also offers a valuable contribution to a critical status quaestionis and a history of modern studies related to the issue of motion). The commentary form is necessary, after all, because of the difficult movement of these Aristotelian texts, which are eminently dialectical: a more removed survey could only lead to oversimplification or misunderstanding of the issues to which Aristotle's analysis strives.The most important result of Giardina's research is the subtle but illuminating distinction between the Aristotelian concepts of energeia and entelecheia. This distinction clarifies two aspects both central and paradoxical of Aristotle's theory. The first is the definition of motion as 'entelechy of what is in potentiality qua such', the second is the definition of infinity as a potentiality outside of the horizon of the energeia, which is thinkable in the tension between the potentiality and the entelechy of what is in potentiality qua such.Giardina develops some important analyses of the issue of motion, of the efficient cause and of its relationship with the entity in which the movement happens (which is at the same time the energeia of what moves and the entelecheia of what is moved). The investigation on Aristotelian critique of the theories of the infinite proposed by his predecessors is equally detailed: it turns out that for Aristotle the apeiron is a concept as inevitable for the understanding of time, of the continuous quantities and of motion itself (in the background there are Zeno's paradoxes), as aporetic if the infinite is conceived as substance or body.These observations do not do enough justice to all the rich content of Giardina's work, which stands out as an indispensable contribution to a fine understanding of some of the more complex pages of Aristotle's Physics. (Mario Vegetti)