In this paper everyday reasoning is examined fromm the standpoint of natural logic. In natural logic there is the supposition of the concept of schematisation, i.e. the discursive representation of a situation that a speaker A constructs for a listener B and that B must reconstruct for himself.Under these circumstances, in order to prove that a statement s is true A must present it in such a way that B does not call it into question, that he considers it a fact. For this it is necessary to have proofs. Moreover, a fact is never isolated and it may therefore appear inconsistent with other facts. A is thus led to provide reasons in order to substantiate his statements.Some mechanisms of proofs and of reasons are investigated.

The aim of this paper is to highlight the main features of the philosophy of science that are present in Aristotle’s Posterior Analytics. At the same time I attempt to point out some obscure proposals within his metascientific theory and (hypothetically) to distinguish certain aspects in which the Aristotelian Model of science has become inapplicable nowadays.