§ II. Exposition of the System

68. • In the concurrence of two opinions equally or almost equally probable, of which one favors liberty and the other the law, while the doubt stands concerning the existence of the law, it is permitted to follow the opinion favoring liberty; but in doubt concerning the cessation of a certain law, the opinion favoring the law must be followed.²

Conditions to be observed. The use of a probable opinion favoring liberty must be moderated by the following conditions.

1° At least ordinary diligence must be employed so that the truth may be discovered; for this investigation is necessary so that ignorance may be invincible and possession of liberty may be preserved in good faith.

2° The opinion must be truly probable, that is, founded in a reason grave in itself and comparatively, even if it is a little less probable than its opposite. Wherefore an opinion is not solidly probable whenever the opposite is notably or certainly more probable. For a certain excess of probability takes away the suspension of the intellect, and consequently begets probable certainty, as we shall prove below. But in moral matters, since they must be estimated morally, strict certainty and evidence cannot be demanded, but probable certainty (that is, broad or imperfect) must suffice, as St. Thomas teaches. Therefore notable greater probability elides the comparative probability of the opposite sentence, so that this is only slightly or doubtfully probable; consequently an opinion much more probable is now not strictly doubtful, but morally or almost morally certain.³

Therefore the System of St. Alphonsus must always be kept before the eyes as proceeding only in a case of true doubt, or in the conflict of equal or almost equal probability; for an equilibrium of this kind produces a true suspension of the intellect between both parts, and therefore a true doubt, to be resolved only through reflex principles, according to the doctrine of St. Thomas:¹ "Our intellect . . . sometimes is not inclined more to one thing than to another, either because of a defect of things moving it, as in those problems concerning which we do not have reasons, or because of the apparent equality of those things which move it to each part: and this is the disposition of one doubting, who fluctuates between the two parts of a contradiction." But the System does not proceed when either one opinion is notably more probable than the other, or there is a single probable opinion. For in that case there is not strict doubt, but a sufficient motive, in moral matters determining the intellect to give assent to such an opinion and to follow it as sufficiently certain.

Then, when one opinion is certainly and without any hesitation more probable, it can only be notably more probable.² Therefore no one is bound to embrace an opinion as long as he does not in the least doubt concerning its greater probability.

3° Liberty must be in possession against the law, that is, according to what was said above in n. 65, the certain right of liberty must precede the doubtful law.

69. • It helps in this place to clarify two locutions of St. Alphonsus.

1° The Holy Doctor sometimes says that a law, in order to oblige, must be certain and manifest;³ but sometimes he says that it obliges, although it is not altogether certain, provided it is notably more probable.⁴ Yet in no way does he contradict himself. For a twofold moral certainty, of which the Holy Doctor speaks here, must be distinguished, namely one strictly so called, or perfect, which is evidently deduced from certain principles of morals; and one broadly so called, or imperfect, whose arguments, even if they do not beget evidence, nevertheless so convince that the opposite remains only doubtfully or slightly probable. The former is not required in moral matters, but the latter suffices. Hence the sense of his words is that the law, in order to oblige, must indeed be certain and manifest, but that broad certainty suffices, without need of strict certainty. In the same way we say that an opinion notably more probable is morally certain.

2° Sometimes he distinguishes doubt from probability, and says that in doubt concerning the cessation of the law the law must be observed, but otherwise if probability is present. This ambiguity vanishes if it is attended to that the Holy Doctor understands in the former case strict doubt, namely when there are two opinions almost equally probable according to the doctrine of St. Thomas already related in n. 68; but in the latter case an opinion which alone is probable, or whose opposite rests on no reason.

That the system expounded is the genuine system of St. Alphonsus is luminously proved by Vind. p. 1-125. 2nd ed., T. I, p. 453 sq.