John Allen wrote about the papal election: “No matter what happens, the church almost certainly won’t reverse its bans [my emphasis] on abortion, gay marriage or women priests.”
Ralph McInerney, who should have known better, also referred to the Church’s “ban” on contraception.
The use of the words “ban” or “prohibition” are profoundly misleading, since these words refer to an act of the will.
However, the magisterium of the Church is not an act of the will, but of the intellect. It is matter of judgment. That is, the Church through its various organs, councils, synods, popes, and theologians, makes a judgment about a matter of the moral law. This judgment is guided by the Holy Spirit into a gradual attaining of the truth. At certain points the judgment becomes infallible – that point is sometimes a matter of debate.
The Church has not “banned” contraception or abortion; it has made a judgment that these actions are intrinsically wrong and contrary to the structure of reality that God has created.
Similarly, although it is matter of the sacramental order rather than the moral law, the Church has decided that only bread made from wheat (not rice) and only wine made from grapes (not cherries) can be made into the Body and Blood of Christ at Mass. Any attempt to use other materials would not work, as it is contrary to the sacramental structure. In the same way only a male can be ordained a priest; a woman cannot be ordained a priest; any attempt to ordain a woman would not work. Nor, for example, can a person be baptized with rose petals, as some liberal Protestant churches occasionally do.
This does not say that rice is inferior to wheat, or cherries to grapes, or women to men, but that in the structure of sacramental reality only certain things are possible. It is a matter judgment about the structure of sacramental reality.
Of course some people disagree with the judgment, and we must weigh the relative authority of those making the judgment.
Underlying the use of words like “ban” is a voluntarist conception if law– that the Church or the Pope makes the moral law, and can change or dispense from it. An over-emphasis on obedience, or rather on what the Jesuits all “corpse obedience” as opposed to Dominican “rational obedience” contributes to this misunderstanding.