§ 1. Notions

— I. On moral certainty. Certainty in general is defined as the assent of the mind without fear of the opposite. As metaphysical certainty is founded in the immutability of a metaphysical principle, and physical certainty in the constancy of the physical order, so moral certainty rests upon the constancy of the inclinations and morals of men. An exception, indeed, in a particular application is not demonstrated to be impossible; but where there is no reason for suspecting it, to fear an exception is alien equally from reason and from the custom of prudent men. It is alien from reason, because the possibility of error does not create a danger of error, which danger would give a legitimate cause of fear ¹. It is alien from the morals of men. With Aristotle ² and St. Thomas (3) all easily understand this: "Certainty is not to be sought in the same way in every matter." And they call morally certain that which, although it is not strictly demonstrated, nevertheless is assailed by no serious reason and is supported by reasons persuasive in a human way, under which, nevertheless, in some case, falsity can lie hidden. Thus we are certain concerning the baptism which the priest, the minister, testifies that he conferred upon us.

Hence, under another respect, moral certainty can be called that with which men are accustomed to be content in acting. St. Thomas, in the place cited, calls that certainty probable, i.e., such "as for the most part attains truth, although in fewer cases it falls short of the truth" ¹.

But if it is established, in a particular application, that an exception is excluded by a certain argument (v.g., in the demonstration of the Catholic religion, or in certain points historically proved by several witnesses), there will be moral certainty more strictly than when simply the reason of exception does not appear.

Moral certainty excludes not every fear, but only prudent fear.

But by an extended name, a judgment is called morally certain which, although in itself it is only probable, so that it can found only opinion, nevertheless practically permits the application of a certain moral principle, such as this one is: in doubts one must answer in favor of liberty (cf. Schiffini, Princ. n. 34, obj. 4).

Certainty then, in this latter case, is only practical, while that which is properly called morally certain is speculatively certain.

To this also belongs the case of a proposition which is urged only by a probable argument, to which nevertheless no positive argument is opposed. That opinion will be called morally certain insofar as it is certainly permitted to act according to it.

Therefore that is called morally certain equivocally which is demonstrated by convincing reasons from the morals of men, and that which merely rests upon a probable reason to which there is no contradiction. The former certainty also has a place in the logical part of philosophy; the latter is proper to the moral discipline.

Finally, by a different use, all certainty which is to be attributed to the command of the will is called moral.

¹ Schiffini, Principia philosophica, n. 232.

² Ethic. Nicom. L. I, c. 1 and c. 3. - (3) 2, 2, q. 70, art. 2.

¹ For this reason Aristotle was able to define (I Top., c. 12) a probable opinion: "that which seems true to all, or to most, or to the wise, and either to all, or to most, or to the most notable."

— II. On doubt and probability. 1. Even after the diligent inquiry which is prescribed has been made, according to the merit of the cause and the abundance of investigation, we do not always arrive at certainty, even moral certainty; but, after the reasons for and against have been weighed, the intellect of itself remains doubtful, or, at the command of the will, assents to one part with a reasonable fear of the opposite: "it indeed accepts one part, yet always doubts concerning the opposite" ¹. Then it is found in the state of one opining ².

When assent is suspended, the state of mind is called strict doubt. Strict doubt is also had when reasons appear for neither side (v.g., whether the stars are even in number). Yet this much differs between the two cases: when reason is lacking, the state of strict doubt is incurable; while, when there are positive reasons, the very suspension of mind can be removed by bringing in the state of opinion or of an opinative judgment. This state is called broad doubt. In it, nevertheless, as we noted above, n. 340, no greater truth is perceived than in strict doubt.

2. Moreover, "a probable opinion is generally considered to be that which rests upon a grave foundation, although not altogether certain, and at the same time has against itself no convincing reason" ³. But a grave motive is that which, not only simply or separately, but also comparatively, or with the opposing reasons looked through, inclines a prudent man to assent, although it does not determine assent ⁴:

a) From the object, probability of law and probability of fact are distinguished, in the same way in which, n. 55, we separated ignorance of law from ignorance of fact;

b) From the source whence it is drawn, intrinsic or extrinsic probability is distinguished, according as the motive of assent is taken from intrinsic reasons or from the authority of doctors. It would be better to say probability known from within or from without;

c) From the varying degree of probability, two opinions which are compared with each other can be equally probable, on behalf of which motives of equal or almost equal weight contend; one can be more probable, the other less probable, when one rests upon motives which are not moderately stronger than the motives of the other, although they do not remove the hesitation of the mind.

¹ St. Th., De veritate, q. 11, art. 1.

² Schiffini opportunely notes, Princ. n. 221, that fear of the opposite can nevertheless be excluded because the mind does not advert to the danger of falsity: which is often the case of the unlearned. He calls this the state of "unperturbed opinion."

³ Reiffenstuel, Theolog. mor. tr. I, q. 4, n. 41.

⁴ We think that what is often written must be explained or corrected thus: that a probable opinion is that which rests upon a motive which moves a prudent man to assent. For since a motive does not move the intellect except by its evidence, it would follow that no opinion could be probable unless it were estimated by learned men to be certain.

— Which opinions are to be judged probable?

Preliminary warning. 1. As those things teach us which we weighed in n. 350 concerning the moral certainty with which practically we can and ought to be content, a law or obligation cannot be called doubtful on account of any reason whatever that has been thought up or alleged; rather it is necessary that, all things having been sufficiently looked through, this reason be grave and solid and remain.

Remain, I say. For since probability implies obscurity (insofar as it denies certainty looked through), this obscurity can be expelled, not only by decrees given authoritatively, but also by the approved studies of doctors. Moral science does not ignore progress. And many things which formerly, for some time, were probably put forward, would today be affirmed only rashly.

Thus St. Alphonsus ¹ was able probably to assert that excommunication is not incurred by a priest who feigns that he absolves an accomplice: which today, even before the Code, has been wholly exploded by responses of the Holy Office. Thus also that opinion which, because of error, exempts from restitution him who voluntarily applies fire to another's house but which he thought to be that of Caius, while it was that of Titius, seems to us exploded by the very protests of common sense; yet C. de Lugo ² defended it, and St. Alphonsus (3) judged it probable. Nor do we any longer hold as intrinsically probable the opinion which exempts from injustice a priest who secretly retains for himself part of the stipends of manual Masses whose burden he transfers from himself to others. For the reason for doubting, already well solved by St. Alphonsus (4), is shown to be clearly vain by the excellent and ample dissertation of Fr. Arendt, S.J., "On the Injury to Commutative Justice in the Stipend of a Manual Mass Diminished for Another Celebrant."

Wherefore the present state of the controversy must be attended to.

2. Confusion must be avoided. Once this preliminary warning has been made, lest the answer to be given to the question be wrongly understood, a judgment concerning the probability of opinions must be accurately separated from a probable judgment concerning a thing or action. Concerning many things even the unlearned probably judge; concerning the honesty of an action all can and ought to have at least a probable judgment, although it is obtained in one way in one person and case, and in another way in another. Cf. what is to be said below. But here the matter is about the opinion itself by which, v.g., a certain action is predicated as probably honest.

3. The estimation concerning the intrinsic probability of an opinion requires an examination of the reasons and difficulties: which examination belongs only to experts in theology or in the science upon which the solution depends. Wherefore not even for every priest or confessor is that judgment accessible. Cf. Ballerini-Palmieri ¹. And if the doubt turns upon the interpretation of law, the theologian will not rarely be compelled to borrow light from the jurist.

An opinion is called extrinsically probable to which five or six authors of good name adhere, who have examined the matter and have not merely copied one another without examination. Concerning this probability even the moderately learned can judge, who, once the state of the question has been understood, find probability admitted among several expert and prudent authors who have considered the matter from within.

Indeed, from the authority of one man an opinion can be estimated as probable, although he departs from the common opinion, "whenever, namely, the author is beyond every exception, that is, very skilled in law both natural and positive, who besides has been accustomed to strengthen his conclusions by firm and valid reasons, who is judged a lover of truth rather than of novelty, and finally who has plainly discussed and weakened the arguments of others" (2). Here therefore, as often, probability coalesces from reasons partly intrinsic, partly extrinsic. Cf. B.P. I, n. 185. The more the matter is estimated as doubtful or difficult, and therefore the less there is in that matter a certain common opinion, as, v.g., the question concerning the grave violation of the vow of poverty, the more easily the authority of a prudent and learned man will suffice for the opinion to be judged probable.

But observe this: since authors are not legislators, the whole force of extrinsic probability must be derived from a presumed intrinsic reason.

Yet a distinction must here be observed between an immutable law, such as the divine law is, and laws which can be changed by human authority. Since the Church herself recommends that we follow approved authors, even he for whom the falsity of some interpretation which grave authors defend has been looked through is not prohibited from acting according to their opinion. And after some time received opinions found a usual interpretation concerning which this holds: "Custom is the best interpreter of laws" (c. 29). And in vain then, from monuments, you will have demonstrated another signification of the law, since according to those received opinions the law must be judged to have been tempered. Thus the Code itself, c. 6, 2°, wills that canons which reproduce the old law in full be estimated from the interpretations received among approved authors. Thus, even if you should prove, with attention paid to the first decrees, that all jurisdiction over an accomplice, also in order to other sins, has been taken away from the confessor, nevertheless, since the contrary opinion is that of many approved authors, jurisdiction over the other sins remains probable and therefore practically certain.

¹ Theol. mor. l. 6, n. 556. - (2) De iustitia et iure, d. 17, nn. 75. 76. - (3) Op. c. l. 3, n. 628. - (4) L. 6, n. 322.

¹ Op. theol. I, tr. 2, n. 191.

² Ball.-Palm. I, tr. 2, n. 186.

— Probable judgment concerning the honesty of an action to be done. 1. In order that he may obtain for himself a probable judgment concerning the honesty of his action, an unlearned man who doubts or hesitates usually must be led by another's authority; and commonly he can also stand by the judgment of one man whom he rightly holds to be instructed. Thus those unskilled in theology can acquiesce in the parish priest or confessor, unless they have a positive cause for suspecting their ignorance or rashness in certain matters; or unless they themselves, in certain arguments, for example in knowledge of law, are more versed.

2. Nor are they prohibited from approaching several upright confessors or doctors, if perhaps the first one questioned has answered too severely. But if they have obtained truly contrary responses from expert men, they will be able of themselves to estimate the matter as positively uncertain, so that they preserve free option.

3. Theologians themselves who are not so learned can trust the authority of a prudent writer who reports an opinion as extrinsically probable. Yet they will have to dissolve a positive suspicion of error according to the merit of the cause and according to the abundance which they have. Indeed, concerning an author of the gravest and most approved authority, such as St. Alphonsus, it has been answered that it is permitted for a priest confessor to follow his opinions simply, with no other selection made. This, as is clear, must be taken insofar as either a decree of the Holy See or a changed law has not clearly taken away the probability of the opinion. Cf. resp. S. Paenitentiariae, 5 July 1831. A.S.S. I, 497, or Bucceroni, Enchiridion, 4, p. 9.

3. Nor is a learned theologian obliged to examine all things by himself; but he himself can work according to an opinion which learned men defend as probable and safe. And it belongs to a prudent man not so to trust, at least in graver matters, his own judgment, that he neglects to confirm his own persuasion or opinion by consultation with or questioning of others.

— On a safe and a safer opinion. This must carefully be observed: an opinion is called safe and safer under a diverse respect. An opinion is called safe with respect to formal sin, which you can follow without fault; while it is called safer with respect to material sin. That opinion is safer which, whether it is more or less probable, nevertheless removes more every danger of material sin. Therefore it is the opinion for the law, for the obligation. Hence Titius can embrace the safe parts even when he follows the less safe opinion.