§ 1. On Opinions Considered in Themselves

61. I. Intrinsic, absolute probability is the appearance of truth which an opinion bears before itself in itself, considered in its motives, and independently of any opposite opinion. From this it is clear that an opinion, considered in itself, is more or less probable according as the weight of the reasons on which it rests is greater or lesser. Hence various GRADES of probability are distinguished, which nevertheless all can be reduced in practice to three, namely to a solidly probable opinion, to a most probable opinion, and finally to a slightly probable opinion.

1. A TRULY AND SOLIDLY PROBABLE opinion is that which indeed rests on a fallible foundation, but on a foundation so firm that it can draw to itself the assent of a prudent man, although with fear of error.

But that such probability be present in an opinion, it is required: a) that it rest on a motive not of just any sort, but grave relative to the matter to be decided; b) that it be opposed neither to Sacred Scripture, nor to tradition, nor to the definition of the Church, otherwise its falsity would already be established; c) that there not be opposed to it a convincing reason to which no adequate response seems available (I, 79 and 82).

To the genus of opinions truly and solidly probable belongs a sufficiently probable opinion. For although the motive on which it rests is not of the same firmness as in an opinion which is called truly probable, nevertheless it is sufficient for moving the mind of a prudent man.

2. A MOST PROBABLE opinion (taken in itself and absolutely) is that "which rests on a very grave foundation, wherefore the opposite is judged slightly or doubtfully probable" (I, 40, 81). See what is to be said n. 71.

3. A SLIGHTLY PROBABLE opinion is that which rests on some foundation, but not such that it can draw to itself the assent of a prudent man.

Scarcely different from it is an opinion doubtfully, or even probably probable, which, although it is not wholly lacking a prudent motive that it is true, nevertheless does not have a foundation either certain or sufficiently grave, such as is required to constitute true probability (I, 81; Vind. Alph., I, p. 8).

The reason why a probably probable opinion is not to be called absolutely probable is thus set forth by Viva: For just as certitude or evidence concerning the probability of an opinion does not pour certitude or evidence into the opinion itself, so probability concerning the probability of an opinion does not pour probability into the opinion itself (Thes. de opin. probab.).

Outside the limits of probability is an IMPROBABLE opinion which, as being opposed to a morally certain opinion, is judged destitute of every element of probability, and therefore deprived of every hope of truth (I, 40). Frequently, however, some opinion is called improbable, namely practically, although in itself it is not destitute of every probability (cf. n. 73).

62. Note. 1. Only learned men and those versed in moral matters can judge concerning the intrinsic probability of opinions, since they alone can know that nothing certain is opposed to them. For many times to men talented, but little instructed in moral science, that seems evident which the skilled judge false. As regards particular cases not discussed by theologians, that opinion is sufficiently probable for a learned and timorous man which, after a serious weighing of reasons and consultation of doctors, without disordered affection, he shall have judged to be such.¹

2. The unlettered can with a safe conscience follow the opinion or counsel of a pastor or confessor, or of another prudent and learned man.

63. II. As regards EXTRINSIC probability, the following rules must be held:

1. An opinion which, while the Church tolerates it, is common among theologians must be held probable.

But the common opinion of theologians must by no means be confused with the unanimous opinion of theologians. Their unanimous opinion is no longer opinion, but a morally certain truth. For since all preachers, catechists, and confessors hand down that which is unanimously taught, if they erred, the Church, by dissembling a common error, would tacitly approve the false and would lead the Christian faithful into error, and therefore she herself would err. On the contrary, a common opinion is not a certain truth, but is only an opinion which approved authors generally hold, and to which therefore the greatest authority belongs.² An opinion is called more common when notably more authors stand for it than for the opposite (therefore of itself it does not equal a common opinion); most common, when the consensus of authors is almost unanimous. Cf. Beaudouin, q. IV, dub. IV.

2. A proposition which several (at least five or six) theologians, distinguished in probity and judgment, hand down must also generally be judged probable.

We said generally: for only the Supreme Pontiff teaching from the Chair enjoys the prerogative of infallibility. And therefore, when there appears for some proposition a certain convincing reason or authority, to which no adequate response seems available, then the contrary opinion cannot be held as probable.³

3. One author does not suffice for some opinion to be called truly and sufficiently probable, if indeed the question is of an author of whatever note, since this proposition was condemned by Alexander VII under n. 27: "If a book is of some younger and modern author, the opinion ought to be judged probable, so long as it is not established that it has been rejected by the Apostolic See as improbable."⁴

Yet if the matter concerns an author grave and of great name in the Church, and greater than every exception, we can, provided he teaches nothing against Scripture or the common sense of the Church, follow his opinion as probable.

4. Sometimes also, although rarely, the authority of one doctor can constitute an opinion probable, and even more probable against the common opinion of others; namely if that author is very learned, upright, and prudent, not a lover of novelties, and brings forward a valid reason which has not been sufficiently solved by others.⁵

5. Lastly, a proposition must be judged probable which some great theologian testifies to be probable, although he himself hands down the contrary as more probable.⁶ But a great theologian is esteemed to be one who has great authority among theologians because of his excellent doctrine, prudence, and probity.

Such, according to St. Alphonsus, are: Suarez, Soto, Azor, Canus, Sylvius, Cajetan, Banez, Navarrus, Paludanus, Toletus, Sylvester, Lessius, Molina, Sanchez, Angelus, Vasquez, Armilla, Valentia, Laymann, de Lugo, Castropalaus, Bonacina, Emmanuel Sa, Pontius, Cabassutius, Collet, Roncaglia, the Salmanticenses, Petrocorensis, Abelly, Cardenas, Coninck, Gamachaeus, Isambert, etc., besides St. Thomas, St. Bonaventure, St. Antoninus, and Scotus, whose authority certainly ought to be preferred to others.⁷ Finally, to these most learned men St. Alphonsus comes to be numbered, whose authority we already know to be so great (cf. preface).

64. It is asked. Whether extrinsic probability constitutes true probability.

Resp. 1. There are those who wholly reject extrinsic probability; there are those who extol it too much. That extrinsic authority sometimes, with the things to be observed being observed, constitutes true probability is clear from Scripture (Prov. 22:17), where it is said: Incline your ear, and hear the words of the wise; and elsewhere (Prov. 3:5): Do not lean on your own prudence. But he is denied to lean on his own prudence who so obeys the authority of the wise that, on account of it, his own proper opinion sometimes being left aside, he girds himself for work (cited Dissertation, n. 80).

It is clear also from the response of the Sacred Penitentiary, issued in the year 1831 and confirmed by Gregory XVI: "that the confessor who in the tribunal of penance follows the doctrine of ST. ALPHONSUS DE LIGORIO is not to be disturbed, even if he does not weigh the arguments and reasons on which his various opinions rest, but on account of this reason alone, that in his works nothing worthy of censure was found." For unless extrinsic probability sometimes constituted grave, true, and firm probability, it is certain that this solemn declaration would never have been issued.

We said: with the things to be observed being observed, because for the practical use of extrinsic probability the rules of the moral system must be observed.

2. For the rest, if the matter is weighed well, it is clear that extrinsic probability is resolved into intrinsic probability. For from the fact that distinguished doctors hand down some opinion, there arises a valid presumption that that opinion is supported by grave reasons.

Whence St. Thomas (2.2, q. 4, a. 8, ad 2): "Someone of little knowledge is more certified concerning what he hears from someone scientific than concerning what seems to him according to his own reason." "And in truth," adds St. Alphonsus (l. c., n. 83), "if I, less learned, were to follow the opinion of St. Thomas against the reason which seems more probable to me, who would deny that I would act more prudently if, my own opinion being suspended, I deferred to so great an authority?"

65. Concerning the authority of writers (lest it be extolled too much), these things are to be noted:

1. The authority of writers is to be estimated not from their multitude, but from their gravity, and from the reasons on which they rest. Moreover, among grave authors themselves, those are to be preferred: a) who have treated the matter expressly;¹ b) who have confirmed by experience the doctrine which they hand down, for example, by hearing the confessions of many: for experience is the best mistress; c) finally, those who, led by love of truth alone (such as the saints are), devoted themselves to writing (cited Dissertation, n. 87). Cf. Ami du Cl., 1900, p. 613.

2. As regards casuists, the more recent are to be preferred to the older, who wrote after the condemned opinions, namely concerning those questions which regard the condemned propositions, or which are related to them. Recall what was said n. 4.

66. As regards the opinions of St. Alphonsus himself, it can most truly be affirmed: they generally enjoy the highest authority, or extrinsic probability. For: 1. All those things which conciliate the highest authority are fully present in the Blessed Doctor, namely holiness of life, singular love of truth, study and untiring investigation through many years, long experience, outstanding knowledge, and the highest obedience toward the Holy See. 2. His opinions, even those which depart from the common opinion of the older theologians, have now today become, at least for the most part, common or more common. 3. These opinions are taught universally, not only while the Church tolerates them, but while she truly approves them: approving them indeed not in a definitive sense, but in a sense both permissive and also elective; so that several times they have been commended by the Holy See itself to professors and confessors as sound, safe, and most salutary (Vind. Alph., Preliminary Dissertation, § 2).