The role of induction in the cognition of non-demonstrable principles in Aquinas

The analysis of the 20th lectio of the second book of the Aquinas?s Commentary on the Posterior Analytics shows that he recognizes four types of non-demonstrable principles: axioms, definitions, hypotheses and so-called causal principles. The comparison of the axioms and the causal principles shows that the induction is necessary for the cognition of later ones; the interpretation that induction has the role in the cognition of all types of non-demonstrable principles is dismissed. The article makes the distinction between broad sense of induction (all cognition with the basis in sensed singulars) and strict sense of induction (the inductive process described in the Second Analytics). In the strict sense, the induction has no role in the cognition of the axioms; nevertlheless, in wider sense of the repeated sensations its role is to provide sensory information on the basis of which the intellect can apprehend the meaning of the terms used in the axiom.