Abstract
The Platonic description of the cognitive development of the human being is a crucial part of his philosophy. This account emphasizes not only the existence of phases of rational growth but also the need that the cognitive progress of the individuals is investigated further. I will reconstruct what rational growth is for Plato in light of the deliberate choice of the philosopher to leave incomplete his schematization of human intellectual development. I will argue that this is a means chosen by Plato to stimulate his readers to use his text as a starting point for an enquiry into the capabilities of human intellection. I will illustrate the presence of two phases in the process of human rational growth, highlighting the different techniques utilized by Plato to promote cognitive development during each of them. When the individuals are in the first phase of intellectual growth, they are rationally stimulated via conventional discursive material transmitted in written form. Human rational progress at the level of sophistication of theoretical adulthood is promoted through mathematics.