The Principles of Psychology According to Saint Thomas Aquinas

Saint Thomas Aquinas' exposition of the principles of psychology given in his Commentary on Aristotle's 'De Anima' concerns three questions: a) the subjective and objective purpose of a psychological analysis; b) the methods (demonstration of fact, causal demonstration, composition or synthesis of informations to prepare a definition); c) the subject of this science, which the soul is. The subjective purpose is a benefit to a philosopher's intellect, because understanding is an intellectual good. The objective purpose is a benefit to the whole system of sciences, because the science concerning the soul at its consequence makes a metaphysical, ethical and physical cognition develop. The result of his consideration on a subject and methods of psychology (principally consideration on the definition of feeling which is an operation done by soul and body together) is that Aquinas concludes the science about soul is a part of physics. This conclusion allow us to say now a rational psychology is a fundamental part of philosophical antropology which concerns a human being and specific human operations.