Jacoby himself quotes several times from Lord Acton, a 19th century critic of the doctrine when it was affirmed at the First Vatican Council. "There is no worse heresy than that the office sanctifies the holder of it" says Acton. But of course Papal Infallibility has nothing to do with sanctification, and the quote reveals the typical basis of the misunderstanding, which is to mistake the doctrine as being primarily about the Pope when it is really primarily about Jesus Christ. Paragraph 890 of the Catechism reads:
The mission of the Magisterium is linked to the definitive nature of the covenant established by God with his people in Christ. It is this Magisterium's task to preserve God's people from deviations and defections and to guarantee them the objective possibility of professing the true faith without error. Thus, the pastoral duty of the Magisterium is aimed at seeing to it that the People of God abides in the truth that liberates. To fulfill this service, Christ endowed the Church's shepherds with the charism of infallibility in matters of faith and morals.
What is a "charism?" It is a gift from God, a grace; the infallibility of the Pope is therefore a gracious act of God primarily, and only secondarily an act of the Pope.
Jacoby compares the authority of the Pope with authority found in Judaism:
But infallible? As an observant Jew, I come from a religious tradition that has always expressed a very different view of religious leadership and authority. In normative Judaism, not even the greatest leader, the wisest sage, or the most renowned rabbi is infallible. The Great Sanhedrin of Jerusalem was the supreme legal and religious authority in ancient Israel: its 71 justices were required to be men of humility, integrity, and compassion, known as much for their scholarship in religious matters as for their wide-ranging knowledge of science, mathematics, and languages. Their credentials were stellar, and their rulings were final.
The appropriate Judaic comparison with the Pope is not the Great Sanhedrin, however, but with Moses being given the Ten Commandments on Mount Sinai. It would be an obvious mistake to suppose that those who hold the Ten Commandments infallible are guilty of supposing Moses to be some sort of superman or "sanctified." For Moses is merely the messenger, and whatever his personal sins and limitations, they are irrelevant to the status of the Ten Commandments, the author of which is God. Similarly, when the Pope pronounces authoritatively from his office on matters of faith and morals, it is not he who is the author of the opinion, but God, and God is not fallible despite the flaws of his servants. Whether the Pope is a great leader or the wisest sage has nothing to do with it.
Jacoby also quotes Acton's famous aphorism about power: "Power tends to corrupt, and absolute power corrupts absolutely." With respect to the Pope, this is a confusion of power with authority. For the doctrine of Papal Infallibility is actually a limit on the power of Popes; the current Pope is bound by the infallible pronouncements of all previous Popes. Those who say that the essence of Protestantism is that it makes every man his own Pope haven't quite gone far enough. The ordinary Protestant is not bound by the decisions of any other Protestant or even his own prior decisions, as the Pope is bound by all prior Papal pronouncements, his own as well as others. Protestant Pastor Joe may get up one day and after reading his Bible one more time, decide that John 6 really does mean that Christ is literally present in the Eucharist, and may preach that from his pulpit that evening. But Pope Francis can never get up one day, read his Bible to the effect that the Catholic doctrine of the Eucharist is hooey, and preach the same that evening, for the doctrine of the Eucharist is settled and unchanging, no matter how wise or profound a skeptic of the doctrine may be.
The article ends with Jacoby telling us that
Pope Francis is described by those who know him as modest and self-effacing, committed to a church "that does not so much regulate the faith as promote and facilitate it." You don't have to be Catholic to pray that the cardinals have chosen well, and that the 266th pope will lead with wisdom, honesty, grace and an understanding heart. Ultimately it is those qualities, not "infallibility", on which the success of his papacy will depend.
Infallibility is another name for the promises Christ has made to the Church to be with her always; if the success of the papacy does not depend on it, then it doesn't depend on Christ or, in other words, it isn't what it claims to be and is really just another man-made institution. In that case, it really does come down to the personal qualities of the Pope. But, then, how could the Pope be wise and gracious if he is gravely mistaken about the very nature of his office?