 Keeping with his earlier statements that his arguments were probable and according to natural principles, Pomponazzi concluded that the question of the immortality of the soul is a neutral problem, meaning that there are no arguments based only on nature that prove either immortality or mortality. His application of the term “neutral problem” was not novel. John Duns Scotus had come to the same conclusion about the immortality of the soul, and Thomas Aquinas regarded the question of the eternity of the world as a neutral problem. Consequently, faith is the ultimate arbiter of the question, and Pomponazzi maintained that Christians must follow the doctrine of immortality that has been established by the Church fathers and Pope Gregory I, who were the greatest experts in divine matters (ch. 15).