First, one needs to distinguish between the church’s doctrines and its dogma. Dogma—the articles of the creeds and the solemn (infallible) proclamations of the popes or the magisterium—constitute the church’s “Rule of Faith.” The correct term is that they are “irreformable,” which means that the direction of the judgment contained in the dogmatic statement cannot be reversed. But dogmas can be reinterpreted by subsequent magisterial actions, as when the Second Vatican Council developed or reinterpreted the First Vatican Council’s definition of what is usually called papal infallibility. A careful reading of the decree actually says that when the pope speaks ex cathedra in the exercise of his office, he possesses by divine assistance that infallibility which the divine Redeemer willed his church to enjoy. In other words, the pope does not possess infallibility, but rather, it is a charism of the church that, under certain limited circumstances, he can exercise.