In the De Generatione et Corruptione II 9, Aristotle aims to achieve the confirmation of his theory of the necessity of the efficient cause. In this chapter he sets out his criticism on the one hand of those who wrongly attributed the efficient cause to other kinds of causality and on the other, of those who ignored the efficient cause. More specifically Aristotle divides all preceding theories which attempted to explain generation and corruption into two groups: i) those which offered an explanation by using the formal cause ii) those which provided an explanation by using the material or the instrumental causes. According to Philoponus, when Aristotle reproaches the other philosophers for adducing no proper notion of the efficient cause h...