It is the common teaching of the Church, reaffirmed by successive popes and to be found in all reputable textbooks of moral theology, that the use of mechanical contraceptives which interfere with intercourse is always wrong. Whether this common teaching amounts to the ordinary magisterium in the technical sense and is therefore infallible is another matter, but short of such assurance it would be hard to find a clearer guide for the Christian who wants to know what he should do or not do. It should be emphasized that even those theologians who think there are legitimate uses for the pill nearly always distinguish between this and mechanical contraceptives. It is indeed clear that these are two quite different matters; contraceptives interfere directly with the act of intercourse whereas the pill does not.

It is a mistake to suppose that we do not know anything until we know it infallibly. There are a great many topics about which a Catholic ought to have sure and definite views just because he is a Catholic, even though the infallible magisterium of the Church has not yet pronounced upon them. He should know, for example, without waiting for the pope to tell him, that it is wicked to propose to drop a nuclear bomb on a city under any circumstances. Similarly if a Catholic wants to know whether he should use mechanical contraceptives or not he does not need to wait for an infallible papal pronouncement to get the answer.