St. Thomas Aquinas and the Self-Evident Proposition: A Study of the Manifold Senses of a Medieval Concept

It is customary to credit Aristotle with the discovery, or at least the first extant formulation, of the concept of self-evidence. Recent work in the history of science has suggested that Aristotle was indebted in this respect to earlier Greek geometrical models of demonstration, but these earlier texts no longer survive. However, in our present day, the merits of the ancient discovery suffer from neglect, and the very concept itself is met with suspicion. One finds, for instance, influential textbooks of the history of logic enjoining readers to acquire a healthy skepticism of the concept of self-evidence. Further, it is not uncommon for contemporary philosophers to reduce the concept of self evidence to some kind of subjective feeling of certainty or even persona] preference. The abandonment of the notion of self-evidence among contemporary philosophers is not a procedure limited to practitioners of logic, as representative views can be found among those who practice metaphysics, ethics, philosophy of science, legal philosophy, political philosophy, and epistemology..