§1. By virtue of his office, the Supreme Pontiff possesses infallibility in teaching when as the supreme pastor and teacher of all the Christian faithful, who strengthens his brothers and sisters in the faith, he proclaims by definitive act that a doctrine of faith or morals is to be held.This is the "death by a thousand qualifications" clause in terms of Roman dogma. Is there really anything that is so manifestly evidently defined infallibly that someone cannot come along later and question it?
§2. The college of bishops also possesses infallibility in teaching when the bishops gathered together in an ecumenical council exercise the magisterium as teachers and judges of faith and morals who declare for the universal Church that a doctrine of faith or morals is to be held definitively; or when dispersed throughout the world but preserving the bond of communion among themselves and with the successor of Peter and teaching authentically together with the Roman Pontiff matters of faith or morals, they agree that a particular proposition is to be held definitively.
§3. No doctrine is understood as defined infallibly unless this is manifestly evident.
Case in point: "Fr." John Zuhlsdorf vs. "Fr." Richard McBrien, Crowley-O’Brien Professor of Theology at the University of Notre Dame.
Zuhlsdorf seemingly claims that the ordination of women was infallibly defined as being contrary to the faith by John Paul in Ordinatio Sacerdotalis and then subsequently was reaffirmed by the Congregation for the Doctrine of the Faith (which, interestingly, indicated that Ordinatio Sacerdotalis did not define this as dogma: "In this case, an act of the ordinary Papal Magisterium, in itself not infallible, witnesses to the infallibility of the teaching of a doctrine already possessed by the Church"). In other words, per the CDF, O.S. did not define the dogma - the dogma is infallible via the mechanism of universal and ordinary magisterium.
Of course, Scripture makes it pretty clear that the eldership is for men only, but is it manifestly evident? I'm sure it is for the conservatives, and not for the liberals. Its lack of manifest evidence is not due to any deficiency in the text of Scripture, but simply in the sinful rebellion of mankind.