Abstract
When addressing the first principles of the science of the being and physics, Aristotle presents a special kind of proof in favor of the principle of non-contradiction and the principle of movement. This paper explores the nature of such proofs and tries to show important parallels between them. Indeed, in both cases Aristotle makes use of dialectical arguments which aim to demonstrate that whoever denies these principles necessarily assumes a series of commitments related to language that involve the very principles in question. It is thus shown to what extent the principles which are discussed are a condition of possibility of the discourse itself. Thus, both series of arguments exhibit transcendental aspects, which, especially regarding disputes with the monist, have been often overlooked, and which illustrate the scope of dialectics when it comes to opening the way towards the first principles.