able. With these provisos the proof of the thesis is not very difficult.
3. Whenever there is a solidly probable opinion that a particular action is lawful, there is no certain law forbidding one to perform it. But it is lawful to do what no certain law forbids. Therefore when there is only question of committing sin or not, it is lawful to follow a solidly probable opinion even though the opposite may be more probable.
The major premise of this syllogism is obvious. No opinion can be probable which has a certain law against it. The certain law imposes a certain obligation. On the other hand, if an opinion is probable and acknowledged as such by five or six experts, good, prudent, and learned men, it is impossible that there should be a law contrary to the probable opinion. Or if there is such a law, the law cannot be sufficiently promulgated, or else it would be known to the experts. But a law which is not sufficiently promulgated does not bind; ignorance excuses from its transgression. The minor premise, too, is clear. We are at liberty to do what no certain law prohibits. If indeed I doubt whether an action is forbidden, I am bound to inquire and satisfy my conscience on the point. But whenever there is a probable opinion, this inquiry has been already made by experts, and with the result that no law forbidding the action can be discovered, otherwise the opinion will not be probable. The conclusion then is certain.
Therefore in cases where there is a probable opinion, or a positively doubtful conscience, I may arrive at a certain conscience required for lawful action by reasoning implicitly somewhat as follows: The opinion is probable that this action which I am contemplating is lawful for example, marrying according to my promise a good and suitable person in spite of the prohibition of my parents which indeed does not seem to be reasonable. But if this is so, there is no law forbidding me to do it; I violate no obligation in marrying her. Therefore I may marry her.
4. The proof of probabilism from what we must call at least the toleration of the Church for some centuries will perhaps appeal still more strongly to Catholic minds.
The guardianship of faith and morals has been committed to the Church by her divine Founder. He has promised that she shall not fail in the task committed to her even to the end of time. But if a false doctrine is widely held and publicly taught for some centuries in the Church, and she does not condemn it, does not protest against it, the promise of Christ
