Article — Prümmer, Manuale Theologiae Moralis
Article I. On Certain Conscience
324. Notions. Certain conscience is that which, without prudent fear of erring, judges that some act is either licit or good or evil, and therefore here and now to be done or omitted. Since morally certain conscience is altogether required, so that it is never licit to act with a practically doubtful conscience, it is helpful to explain briefly what certitude is and how it is divided.
Certitude is customarily defined: the firm adherence of the mind to some truth without fear of erring; or, as St. Thomas60 says: "Firmness of adhesion of the cognitive power to its knowable object." Therefore certitude is the effect of evidence (intrinsic or extrinsic). For when some truth appears evident to us, we assent with certitude; but as long as evidence has not been present, neither can certain assent be present. This evidence is sometimes intrinsic, namely if it arises from the very nature of the thing clearly perceived; for example, man has intrinsic evidence concerning the truth of the calculation 2 + 2 = 4. But sometimes this evidence is only extrinsic, namely if it is founded upon either human or divine testimony. Thus a boy is certain that this man is his father, because it has been narrated to him so by trustworthy persons; thus all Catholics are certain concerning the truths of faith, because God Himself revealed them. Truths certainly known from intrinsic evidence are evidently knowable; but truths knowable from extrinsic evidence are evidently credible. But even if certitude arises from the evidence of truth, nevertheless from this it is not licit to conclude that certain and true conscience coincide. For since the dictate of conscience is as it were the conclusion of some reasoning, and since error can slip into reasoning, it follows that conscience can be false or erroneous and nevertheless certain. Hence above in n. 307 we proved that an invincibly erroneous conscience sometimes exists, which indeed is certain, but objectively false. Hence it is said briefly: true conscience regards the truth of the object; but certain conscience regards the subject's firm adherence.
60 3, dist. 26, q. 2, a. 4.
325. Divisions. 1. Certitude is divided into metaphysical, physical, and moral. Metaphysical certitude is founded in the very essence and connection of ideas and excludes every possibility of falsity, and therefore is also called absolute certitude, because the contrary proposition is absolutely false and in itself so repugnant that not even God Himself could make it true. This certitude is conveyed, for example, by the first moral principles: good is to be done, God is to be worshiped, etc. - Physical certitude excludes falsity not indeed absolutely, but with the physical order standing thus. It is physically certain, for example, that I am going to die, that the sun is going to rise tomorrow, etc., because, unless a miracle is going to derogate from the physical order, it is certain that these effects are going to occur. - Moral certitude excludes every fear of erring, with attention to the moral order of things. Thus, for example, I am morally certain that the Pope is a worthy man, that my friend perfectly known to me does not tell a lie, etc.
2. Certitude is divided into strict or perfect and broad or imperfect. For according to the greater or lesser weight of reasons on which it rests, certitude, that is, firmness of adherence, admits diverse grades, which nevertheless can all be reduced to two. Strict or perfect certitude is that which altogether excludes every reasonable doubt, so that its opposite is supported by no prudent motive. Cf. the examples brought above in n. 1 for moral certitude. - But broad or imperfect certitude61 is that which rests indeed on a grave motive, but against which not only the possibility of error stands, but certain lighter reasons also fight. Thus, for example, it is morally certain that the three acts of the penitent are the proximate matter of the sacrament of penance, or that Christ immediately instituted all the sacraments, although some authors hold the contrary. Concerning this broad certitude St. Alphonsus62 writes: "To form the moral certitude of some opinion, it is not required that authors holding the opposite lack every reason even light; but it suffices if that opinion, all things having been weighed, appears so true that there scarcely remains to the contrary the appearance of truth, or that the contrary seems not sufficiently probable." From these words of the Holy Doctor it follows that, whenever he calls some opinion not sufficiently probable, he holds the opposite as morally certain and therefore to be followed.
3. Certitude is divided into speculative and practical. Speculative certitude is that which regards the truth of the thing viewed objectively, without direct relation to a practical case. Thus, speaking speculatively, touches are licit, kisses are not prohibited; but in a particular case this certitude sometimes fails; indeed it yields to contrary certitude. - Practical certitude regards the act to be posited here and now, as clothed with all circumstances, for example, the omission of the recitation of the Breviary is licit for me today because of my infirmity.
4. Certitude is divided into direct and indirect or reflex. Direct certitude is called that which arises from clear internal principles manifestly demonstrating the morality of the act to be posited. Thus, for example, a son says to himself: since due obedience is to be rendered to parents, I am bound here and now to obey my father legitimately commanding. Indirect certitude is not obtained by direct and internal principles, but by indirect principles extrinsic to the thing. For example, a subject doubts whether a matter commanded by a superior is licit or not. But since he is persuaded that the superior is wise and God-fearing, he has recourse to a reflex and most true principle: "In doubt the presumption stands for the superior"; and from this he concludes with moral certitude: therefore I can, indeed I also ought to obey the precept of the superior. Speech will return below in n. 332 concerning these reflex principles.
61 This certitude is called by St. Thomas "probable certitude, which reaches truth in most cases, although in fewer cases it falls short of truth" (S. theol. 2, 2, q. 70, a. 2). The word "probable" here is not taken as it is customarily taken by moderns; otherwise probable certitude would be a contradiction in terms. Modern authors also call this certitude moral and broadly so called (cf. Marc-Raus, Inst. mor. I, 31).
62 Dissertation a. 1755, n. 52.
326. Principle. a) Only certain conscience (whether directly or indirectly) is the right rule of morals; b) but for acting licitly, certitude broadly so called ordinarily suffices.
a) This principle is admitted by almost all theologians.63 The reason is that man is bound to apply serious diligence so that he may conform his acts to just law, as was said above in n. 306. Now unless moral certitude of conformity with law is present, neither has man applied sufficient diligence, because it is not so difficult to obtain practical moral certitude in our actions. Then he who acts without moral certitude concerning the licitness of his act sins by exposing himself to the proximate danger of formally sinning and offending God. Moreover, it is not licit voluntarily to expose oneself to a proximate danger of sinning; for he who does that which he reasonably suspects to be sin virtually and interpretatively wills sin itself. - The same is established from St. Thomas,64 who a) requires for conscience that it be brought into no doubt; b) calls conscience the application of science, that is, of certain knowledge, to an act.65
b) Nevertheless certitude in every respect is not required, but broad certitude ordinarily suffices. For "certitude is not to be sought in the same way in all things, but in each matter according to its proper mode. But because the matter of prudence is contingent singulars, concerning which human operations are, the certitude of prudence cannot be so great that solicitude is altogether removed."66 What St. Thomas here teaches concerning the certitude of prudence, the same holds concerning the certitude of conscience. That broad moral certitude truly suffices for acting licitly also appears manifestly from proposition (3) condemned by Alexander VIII: "It is not licit to follow an opinion even the most probable among the probable."67 For even the most probable opinion is not absolutely certain, and therefore, if it is licit to follow the most probable opinion, likewise it is licit to follow an opinion morally and broadly certain, which lacks absolute certitude. Finally the reason is added: absolute certitude in human acts is often altogether impossible. But no one is bound to the impossible. Therefore absolute certitude is not required in human acts, but broad certitude suffices. - In a few cases broad certitude does not suffice, but strict certitude is required, namely when even a slight doubt renders the act illicit, as is accustomed to happen if there is question of the validity of the sacraments. Hence outside the case of grave necessity it is not licit to administer the sacraments with matter which is not certainly valid.
63 Lacroix (De consc. l. 1, n. 47) cites as adversaries Camargo, Taberna, and certain others of small authority.
64 Quodl. 8, a. 13.
65 S. theol. 1, 2, q. 19, a. 5.
66 Ibid. 2, 2, q. 47, a. 9 ad 2.
67 Denz. n. 1293.
327. Scholion. On practical certitude alone as necessary. Since conscience is an act, as has already often been said, it suffices and is required for acting licitly that practical certitude be present, but not speculative certitude. For in moral theology there are very many controverted opinions in which speculative moral certitude is altogether lacking, for example, whether customs-duty laws are merely penal laws, whether painting is a servile work, etc. Certainly it is altogether impossible in these controversies to obtain speculative moral certitude, because the reasons given on both sides are grave and the Church has given no definitive decision. But acts to be posited not rarely occur from these controverted questions. Then therefore, while speculative doubt stands, practical certitude is to be sought, as will be said in the following article.