Article — Noldin, Summa of Moral Theology
Article Fifth. On Probable Opinion.
223. Declaration. 1. The name opinion is used properly subjectively, improperly objectively. Opinion considered subjectively is a judgment by which the mind adheres to a proposition because of persuasive motives, but with fear concerning the opposite; and opinion considered objectively is the matter itself or proposition to which the mind adheres, because of persuasive motives, with fear concerning the opposite. In this objective sense we speak of probable opinion.
From these definitions it is clear: a. that opinion considered subjectively and probable conscience do not in reality differ: for probable conscience properly is a judgment by which the mind judges that some action is licit or illicit, but with fear of erring; b. that positive doubt accepted in a broad sense and opinion considered subjectively likewise do not differ: for any positive doubt is an opinion.
- The probability of some opinion (or sentence) is that property of the same by which, on account of the motives by which it is supported, it merits the assent of a prudent man, although with fear concerning the opposite. Therefore the reasons by which it can be persuaded and proved constitute the probability of some sentence.
By its nature greater or lesser probability belongs to an opinion according to the diversity of the reasons upon which it rests. Therefore manifold divisions of probability are said equally of opinion: for we speak of an opinion as speculatively or practically, internally or externally, solidly or tenuously, certainly or doubtfully, absolutely or comparatively probable.
224. Division. Probability is divided in many ways:
- Into speculative and practical: the former belongs to an opinion considered in itself and in the abstract; the latter belongs to an opinion considered in the concrete with the circumstances which affect it in particular cases.
From these things it is understood that it can happen that an opinion speculatively probable is not practically probable on account of scandal or the danger of sinning which would have to be feared in the concrete if someone acted according to that opinion. Thus this sentence, that a woman oppressed by force can hold herself passively on account of fear of death, is said to be speculatively, but not practically, probable, because on account of the very great propensity of fallen man into venereal matters there threatens a danger of consenting to shameful delight.1
- Into internal and external: the former is founded on reasons taken from the very nature of the matter; the latter is proximately founded on the authority of doctors. External probability of itself supposes internal probability, namely that the doctors were determined to embrace the truth from internal reasons.
a. According as the weight of the reasons or of the authority by which some sentence is supported is greater or lesser, so also the degree of probability, whether internal or external, is greater or lesser. b. But external probability must be estimated not so much from the number of authors as from their doctrine and prudence, and also from the study and diligence which they used in investigating the truth.
- Into solid and tenuous: the former is constituted by a fallible but nevertheless grave and firm motive, which truly merits the assent of a prudent man; the latter rests upon a slight and empty motive, so that he who gave assent to it would be imprudent.
Therefore an opinion tenuously probable, being destitute of true probability, is in reality not probable. Yet there are authors who by the name of tenuous probability signify some slight but nevertheless true probability.
Into certain and doubtful, according as a grave and solid foundation, which suffices for constituting true probability, belongs to the opinion certainly or doubtfully or only probably.
Into absolute and comparative or relative: the former is had when the motives of the opinion are considered in themselves independently of the opposite opinion; the latter is had when the motives of the opinion are considered together with the opposite opinion and its motives.
To these must be added solitary probability, which is had when there are no opposed reasons, although nevertheless it does not attain certitude. Wherefore an opinion uniquely or solitarily probable is called that whose opposite opinion can be supported by no reason, although nevertheless it itself is not certain. Thus where an upright man, whose faithfulness or unfaithfulness has not hitherto been proved by experience, seriously promises something, his promise is a grave motive of trust, which does not furnish certitude, yet is weakened by no contrary reason. In moral theology, opinions uniquely probable are rare; but if there are any, by the very fact that no reason appears on the opposite side, their probability is greatly increased, so that it almost approaches moral certitude.
1 Cf. Lehmkuhl I. n. 72.
225. On opinions considered comparatively. 1. If opinions are compared with one another by reason of security from sinning where someone follows them, these distinctions must be noted:
a. That opinion is called safe which excludes the danger of formally sinning; b. that is called safer which more excludes sin; c. that is called less safe which less excludes sin. Therefore in the concurrence of opinions, of which one stands for the law, the other for liberty, the safer is that which stands for obligation, because it simply excludes the danger of sinning; the less safe is that which stands for liberty, because it does not exclude every danger of sinning.
a. That is called safe which is removed from evil and its danger; since in the present question there is question of sin, that is called safe which removes sin and its danger. The opinion for law alone is not simply safe, but both the opinion for law and the opinion for liberty can be safe.
b. Although of itself the opinion for law is safer, nevertheless from another source it can happen accidentally that the opinion for law is not safer: for on account of the difficulty of observing the law, an opinion safer in itself frequently practically induces the danger of sin.
c. A less safe opinion does not cease to be simply safe, although the opposite is safer; just as the less probable does not cease to be probable, although the opposite is more probable.
b. It is clear that it can happen that the more probable sentence at the same time is less safe, and that the safer sentence is less probable, because it can happen, and in reality sometimes does happen, that an opinion which stands for liberty is supported by graver motives than an opinion which stands for law.
- If opinions are compared with one another by reason of probability, these distinctions are had:
a. Equiprobable opinions are called those which are supported by reasons equally or almost equally grave: for the moderate excess by which one is supported more than another does not prevent them from being called equally probable.
b. That opinion is called more probable which rests upon graver motives than its opposite, which is called simply probable or less probable.
Note. 1. In St. Alphonsus there also occurs: a. a most probable opinion, which rests upon very grave foundations; its opposite, on account of weak motives, is tenuously or doubtfully probable; b. certainly and notably more probable, whose foundations are certainly and without any hesitation much graver; its opposite is tenuously or doubtfully probable.
Since a notably more probable opinion and a most probable opinion are little distant from one another, they are practically equated.
Although a most probable opinion is not in itself morally certain, but only occupies the highest degree of probability, nevertheless practically it is equivalent to a sentence morally certain in the broad sense.