Non ergo est ex alio genere descendentem demonstrare. The Prohibition of Descensus, Subalternation and the Relation between Sciences.

In the Aristotelian theory of science, subalternation is the only way in which different sciences can be related to each other, and it is the only relation through which there can be exchange or communication between them. Till now the only exegetical tradition that has been at least partially investigated on this respect is that of the Sentences in the XIV century. However, between the XIII and the XIV centuries many authors paid much attention to such a topic. Many interesting reflexions are to be found in the tradition of the commentaries on the Posterior Analytics, even since its Grossatestian beginnings. Generally speaking, such reflections have the tendence to widen the net of possible relationships between sciences, including sciences very distant from each other. In particular, we find hints towards the possibility that either metaphysics or logic can subalternate under themselves all special sciences, and numerous reflexions on the nature and possibility of partial subalternation (for example of one science to two different sciences, or of different parts of one science to different parts of one or more sciences). Besides, those reflexions bear many similarities to those in the commentaries on the Sentences of William Ockham and John of Reading.