To defend the Catholic doctrine of Immortality against the attack of Pomponazzi and the Alexandrists.
In the great controversy with the Alexandrists he opposed the theory of Pomponazzi that the rational soul is inseparably bound up with the material part of the individual, and hence that the death of the body carries with it the death of the soul.
Albertus Magnus argued that the soul is immortal, as ex se ipsa causa, and as independent of the body; Pietro Pomponazzi maintained that the soul's immortality could be neither proved nor disproved by any natural reasons.
Among his works may be mentioned Studii sulla coscienza; Il Fenomeno nelle sue relazioni con la sensazione; Della idea del vero; Della filosofia del diritto presso Aristotile (1885); Il Genio di Aristotile; La Psicologia di Pietro Pomponazzi (1877), and, most important, Essai sur l'histoire de la philosophie en Italie au XIX' siecle (Paris, 1869), and La Psychologie de l'association depuis Hobbes jusqu'd nos jours.
Like his greater contemporary, Pomponazzi, he was a lecturer on medicine at Pisa (1546-1552), and in later life gave up purely scientific study for speculation on the nature of man.
His philosophic theory was identical with that of Pomponazzi, whose De immortalitate animi he defended and amplified in a treatise De mente humana.
The list of professors and alumni is long and illustrious, containing, among others, the names of Bembo, Sperone Speroni, Veselius, Acquapendente, Galileo, Pomponazzi, Pole, Scaliger, Tasso and Sobieski.
In the early Renaissance his doctrine of the soul's mortality was adopted by P. Pomponazzi against the Thomists and the Averroists.