I agree with Cecil in part, and disagree in part. Papal infallibility is limited in the following way:
- The Pope must a priori declare a statement to be infallible, otherwise it is not, unless he states it anew and declares it infallible in a clear and distinct way (usually via a formal edict or Papal bull).
- The Pope’s statements are not infallible unless he speaks ex cathedra (“from the chair”) from which he is presumed to be making a pronouncement for which he has the approval of Jesus himself, as per Matthew 16:18.
- The Pope can only speak ex cathedra and infallibly about moral, religious, or spiritual matters. If the Pope came up to me and told me to wear only red pants from that day forward, I would not as a Catholic be required to do it.
As you can see, however, this still gives the Pope great leeway to make infallible pronouncements. We Catholics believe that the Pope is the successor to Peter and therefore, the Vicar of Christ. His very power, however, is what gives Protestants and others pause, even those who believe in the rectitude of scripture. Usually, such people opine that the power Christ gave that is mentioned in the scriptural passage above - if it did exist - died with Peter. From that point forward, one can only assume that every bishop was thought to have an equipotent ability to make pronouncements about religious affairs, however much such pronouncements might differ from those of others. And that is why Protestants differ from one another in so many points of doctrine, since no one person is presumed to have authority in these matters. We Catholics enjoy, then, what might be described as a lack of chaos in doctrine.