Chapter I — Opinions condemned by the Holy See in the controversy of Probabilism

I. In this whole work I shall first of all recall before the readers' eyes the theses condemned by the Church, that they may be able in advance to guard themselves from the danger of erring. The following, in the controversy of Probabilism, the Roman See proscribed under Alexander VII and the Venerable Innocent XI, Supreme Pontiff:

1. If a Book be that of some more recent and modern author, its opinion ought to be considered probable, so long as it is not established that it has been rejected by the apostolic See as improbable. — Proposition 27 of Alexander VII.

2. It is not illicit, in conferring the Sacraments, to follow a probable opinion regarding the validity of the Sacrament, leaving aside the safer one, unless law, convention, or the danger of incurring grave harm forbid it. Hence it is only in the conferring of Baptism, of priestly or episcopal Orders, that a merely probable opinion must not be used. — Proposition 1 of Innocent XI.

3. I probably think that a judge can judge according to an opinion even less probable. — Proposition 2 of the same.

4. In general, when we do anything relying upon probability, whether intrinsic or extrinsic, however slight, provided one does not depart from the bounds of probability, we always act prudently. — Proposition 3 of the same.

5. An infidel who does not believe, led by a less probable opinion, will be excused of infidelity. — Proposition 4 of the same.

6. It is probable that the precept of charity towards God does not, of itself, rigorously oblige even once in every five years. — Proposition 6 of the same.