Abstract
At the beginning of Posterior Analytics 2.19 Aristotle reminds us that we cannot claim demonstrative knowledge ( epistêmê apodeiktikê ) unless we know immediate premisses, the archai of demonstrations. By the end of the chapter he explains why the cognitive state whereby we get to know archai must be Nous . In between, however, Aristotle describes the process of the acquisition of concepts, not immediate premisses. How should we understand this? There is a general agreement that it is Nous by means of which we acquire both premisses and concepts. I argue that this cannot be the case. Since concepts are simples while premisses are composites (predications of concepts), the two cannot be objects of the same cognitive state. I further argue that, whereas Nous is responsible for our grasp of concepts, the state Aristotle elsewhere calls non-demonstrable knowledge is the one whereby we get to know the premisses of demonstrations