(b) If the doubt is one of fact and insoluble, and a prohibitory law is involved, one is free to act; for it is commonly admitted that legislators do not intend their prohibitions, which are restrictions of liberty, to be interpreted with the utmost rigor. Example: Titus is eating a chicken dinner late on Thursday night when his watch stops. As he has no way of discovering the time, he does not know whether Friday or the end of the dinner will arrive first. He may continue the meal, making no undue delays.
(c) If the doubt is one of fact, and a preceptive law is in question, one must take reasonable precautions to settle the doubt; for the lawgiver wills that those who are subject to the law should make use of the ordinary means to learn the facts on which obligation depends (see above, 384). If the doubt remains insoluble, one may decide in favor of liberty; for it may reasonably be presumed that the legislator does not intend to obligate those whose obligation remains uncertain. Example: Caius doubts whether he has reached the age of sixty, when the obligation of fasting ends. He should try to discover his real age; but, if he can find no real proofs either for or against the age of sixty, he may decide in favor of sixty, if there are some indications that he is of that age.
710. The solutions given above for cases of negative doubt suppose that there is no other or higher law that forbids one to take the risk of deciding in favor of liberty. Hence, in the following instances one must decide against liberty:
(a) in negative doubts when the validity of acts is at stake. Example: Titus is uncertain whether the law requires the age of fourteen for a valid contract of marriage; he is also uncertain whether he is fourteen years old. The doubt of law and of fact does not excuse Titus from the law, if he wishes to marry. He must clear up the doubts, and if necessary he must secure a dispensation.
(b) in negative doubts when reasons of charity or justice forbid one to take risks. Example: Caius is uncertain whether he paid Sempronius for work done for him. He is bound to make inquiries about the matter.
711. Probabilism cannot be applied, therefore, when the mental state of the subject is doubt, weakly founded opinion, or practical uncertainty. But, even when one holds an opinion as solidly and certainly probable, one may not follow it as a moral guide, if there is something in the nature of the object or matter itself which forbids this.
(a) A probability of law favoring liberty may not be followed in those matters in which some natural, divine or human law requires one to follow the safer side (see cases enumerated above, 678, 661). Example: The following opinions are probable; that instruction regarding the Trinity and the Incarnation is not indispensable for salvation; that rye-bread is valid matter for the Eucharist. But in practice it would be unlawful to take the risk of following these opinions, except in cases of extreme necessity, when nothing else can be done.
(b) A probability of fact favoring liberty may not be followed so long as there remains nothing more than probability of fact; for, while the will of the lawgiver may on account of probability of non-obligation change one’s relation to the law from obligation to non-obligation, it does not change facts. Examples: On Friday Titus doubts whether a dish before him is meat or fish; probably it is meat on account of its appearance, probably it is fish on account of its odor. At night Fr. Caius is much fatigued, and doubts whether he has said Vespers. Probably he did not, because he cannot recall what feast will be celebrated tomorrow; probably he did, because he remembers having said Compline.
712. For probabilities of fact, to which as such their system does not apply, Probabilists offer the following solutions:
(a) In certain cases one may take from the doubt of fact its bearing on obligation, by recourse to the manifest will of the legislator as declared in the law itself or expressed through dispensation. Examples: While hearing confessions, Sempronius doubts whether his jurisdiction has already expired. He cannot recall the date of expiration, but, thinking the matter over, he sees that probably the date has not arrived. His difficulty is therefore solved, for the Code (Canon 209) supplies jurisdiction in cases of probability of fact. Titus and Caia wish to marry. There is a doubt whether or not they are first cousins, but it seems that probably they are not so related. Their difficulty is solved by obtaining a dispensation.