Kinds of Certitude

The notions which recur most, and the prior exposition of which is of the greatest importance, are those of certainty, opinion, and doubt. For the sake of completeness we shall add some points concerning the notion of probability, the immoderate use of which has so greatly entangled the treatise on conscience.

I. Certainty is the state of a mind adhering to some knowable thing without a prudent fear of erring. It is said "without a prudent fear"; for an imprudent fear is not always absent even from the certainty of faith. "But sometimes," says Aquinas, "the possible intellect is determined to this, that it totally adhere to one part" (De Verit., q. 14, a. 1). And elsewhere: "Certainty is nothing other than the determination of the intellect to one" (In III Sent., dist. 23, q. 2, a. 4, sol. 3).

Certainty is distinguished into metaphysical, physical, and moral, according as it is founded in the essences of things, in physical laws, or in moral laws, that is, those which govern the inclinations and morals of human beings.

Moral certainty is usually divided into strict and broad. Strict certainty is that of which we have just spoken. Broad certainty is that which includes some prudent fear, or "which does not exclude every prudent fear" (St. Alphonsus, I, 81); hence it cannot be called certainty properly so called, but must be referred to opinion, as will be more evident from what is to be said.

II. Opinion is the state of a mind adhering to some knowable thing with a prudent fear of erring. "But sometimes the intellect is inclined more to one thing than to another; yet that which inclines it does not sufficiently move the intellect to this, that it determine it totally to one of the parts; hence it indeed accepts one part, yet it always doubts about the opposite: and this is the disposition of one opining, who accepts one part of a contradiction with fear of the other" (St. Thomas, De Verit., q. 14, a. 1). And elsewhere: "One opining has thought without perfect assent; but he has something of assent, insofar as he adheres to one more than to another" (In III Sent., dist. 23, q. 2, a. 2, sol. 1). Moreover, one opining gives the fearful assent of which there has been speech to a proposition, or to one part of a contradiction, as true. "One opining," says St. Thomas, "says (certainly with fear) that what he opines is true" (In VI Eth., lect. 8).

Corollary I. One who opines that a law exists does not wholly ignore the existence of the law, but knows it in some measure, or truly has a positive cognition of it, although a weak one.

Corollary II. One who opines that a law exists holds the opinion favoring the law as certainly more probable, but the opinion which supports liberty as certainly less probable. But since a small excess of probability is commonly not clearly, and therefore not certainly, perceived, an opinion that is certainly more probable will commonly be notably more probable, or certain in a broad sense, imperfectly and improperly (cf. St. Alphonsus, Lettere, III, n. 219).

III. Doubt is the state of a mind fluctuating between two parts of a contradiction because of no motives, or because of equal motives on both sides. "Our intellect," says the Angelic Doctor, "stands in different ways with respect to the parts of a contradiction. For sometimes it is not inclined more to one than to the other, 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 toward each part: and this is the disposition of one doubting, who fluctuates between two parts of a contradiction" (De Verit., q. 14, a. 1). Again: "When a man does not have a reason for one part more than for the other, either because he has one for neither, which belongs to one who does not know, or because he has one for each, but an equal one, which belongs to one doubting, then he in no way assents, since his judgment is in no way determined, but is equally disposed toward different things" (III Sent., dist. 23, q. 2, a. 2, sol. 1). Nor does St. Alphonsus speak otherwise: "A doubtful conscience is that which suspends assent for each part of the doubt, and remains uncertain and hesitating" (I, 20). "A doubtful conscience is that which, remaining undeliberated, suspends assent for each part" (Homo Apostolicus, tr. I, n. 12). Therefore the Doctors whom we have cited teach that one doubting gives assent, not even a weak assent, to neither part of a contradiction as true. St. Alphonsus gives the ultimate reason for this matter in these words: "For although, when reasons of equal weight support each opinion, each would have force to move the intellect to assent if they were not mutually opposed; nevertheless, since here they are directly opposed to each other, each is now deprived of the force of drawing assent to itself, and by reason of the equality of the weights one destroys the other, and both therefore bring forth nothing except mere doubt" (Dichiarazione del Sistema, appendix, n. 21).

Suspicion is reduced to doubt, that is, the state of mind in which either opinion seems to someone doubtfully more probable. "As all," says St. Alphonsus, "both Probabilists and Antiprobabilists, agree, when there is a slight preponderance between two opinions, so that the excess is very slight and doubtful, then both opinions are regarded as equally probable according to that common axiom: A little is reckoned as nothing" (I, 55, 7th ed.). Likewise St. Thomas: "Certain acts of the intellect have unformed thought without firm assent, whether they incline to neither part, as happens to one doubting, or incline more to one part, but are supported by some slight sign, as happens to one suspecting, or adhere to one part, yet with fear of the other, which happens to one opining" (II-II, q. 2, a. 1). Again: "Reason takes what is little as though it were nothing" (I-II, q. 14, a. 4).

Doubt, or a doubt, is distinguished:

1. Into strict and broad doubt. Strict doubt, or doubt properly so called, is that which we have just described. Broad doubt is some such doubting or hesitation which remains in the state of opinion; hence it is only doubt taken improperly.

Strict doubt is divided into positive and negative, according as someone doubts because of equal or nearly equal motives, or because of no motives, or slight motives, on either side.¹

2. Into speculative and practical doubt, according as the doubt concerns the morality of an action considered in the abstract, for example whether it is licit to paint on a feast day, or concerns the morality of an action viewed in particular, for example whether it is licit for me to paint on this feast day (St. Alphonsus, I, 21).

3. Into doubt of law and doubt of fact. Doubt of law is had when there is doubt about the existence, sense, extension, or cessation from within of a law or disposition; for example, if there is doubt whether it is licit to paint on a feast day. Doubt of fact obtains when there is doubt about a particular fact or thing on which the application of a law or disposition to a particular case depends; for example, if there is doubt whether someone has fulfilled the law or is excused from the law. Yet authors do not agree in delineating doubts of law and of fact.

IV. Probability, or a probable sententia (opinion),² is taken by different persons in a different sense. Some call that opinion probable which rests on a grave foundation, even though perhaps on a foundation certainly less grave than the foundation of the opposite opinion; so the Probabilists. Others require that it rest on a foundation equally or almost equally grave as the opposite; so St. Alphonsus (Dell' uso moderato, c. 5, n. 25). Others require a foundation so grave that it merits the assent of a prudent man; this belongs only to the more probable opinion; so commonly the philosophers.³ An opinion thinly or doubtfully probable is not called probable except improperly.

A probable opinion is distinguished:

1. Into probable absolutely, or in itself, and probable comparatively, or relatively, according as it is probable viewed in itself alone or compared with the opposite. What is comparatively probable is either far more probable, or most probable; or certainly, or much, more probable; or equally, or almost equally, probable; or, as others add, certainly, or much, less probable.⁴

2. Into probable in the logical sense and probable in the ethical or practical sense. Probable in the logical sense is what has grave reasons, or reasons fit for proving. Probable in the ethical sense is what has reasons so grave that, at least by force of a reflex principle, it can direct actions, or be approved for practice.

3. Into probable intrinsically and probable extrinsically. An opinion is called probable intrinsically if it is probable because of intrinsic reasons; probable extrinsically if such great extrinsic authority supports it that, because of that authority, it is prudently held as intrinsically probable. From these things it is clear that extrinsic probability is resolved into intrinsic probability. Besides, concerning extrinsic probability, first note proposition 27, condemned by Alexander VII: "If a book belongs to some junior and modern author, the opinion ought to be judged probable so long as it is not established that it has been rejected by the Holy Apostolic See as improbable."⁵ Then observe these things:

a) "The authority of writers must be estimated not from their multitude, but from their weight; so that the authority of few, or even of one doctor endowed with special knowledge and piety, is sometimes to be preferred to many others" (St. Alphonsus, Diss. de usu mod. op. prob., n. 88, year 1757).⁶

b) The authority of St. Thomas and St. Alphonsus is very great. That St. Thomas is to be preferred to all others, no one today will deny. Moreover, from the various ecclesiastical documents by which the doctrine of St. Thomas is celebrated and inculcated in an entirely singular way, it is enough to recall to mind the encyclical Aeterni Patris (4 Aug. 1879), the Motu Proprio of Pius X, De Studio doctrinae S. Thomae in scholis catholicis promovendo (29 Jun. 1914), and canons 589, § 1 and 1366, § 2.

The very great authority of St. Alphonsus is clear both from the fact that he was raised to the dignity of Doctor of the Church,⁷ and from the many, and singular, praises by which the Church has not ceased to adorn and commend his doctrine.⁸ Hence in controversial matters those authors should be consulted cautiously who easily withdraw from the doctrine of St. Thomas and St. Alphonsus, and who are struck by these words which Mercurelli, at the command of Pius IX, wrote back to Vitozza, who had defended the doctrine of St. Alphonsus against Ant. Ballerini: "His Holiness judged it commendable that you undertook to defend the praises bestowed by the Church upon the doctrine of St. Alphonsus, and that you took pains to meet the malice of those who, abusing the dispositions instituted concerning that same doctrine, tried to depress it."⁹

c) Concerning the manner in which St. Alphonsus gives his judgment about the value of opinions, it is useful to note these things:

(alpha) Generally, for him that opinion is practically probable which he calls probable.

(beta) If he calls one opinion more probable and another probable, he understands them as doubtfully more probable and doubtfully less probable, so that the latter too is held by him as practically probable.¹⁰ If concerning some opinion he says, "It is said not improbably," or "It does not seem improbable," or "Authors say probably," or, for example, "Lugo probably says," then regularly he holds the opinion in question as practically probable. If, once the doctrine set forth has been proved, he adds, for example, "Lugo observes," commonly he approves such an observation.

(gamma) If he writes, "The Doctors say that it is probably licit," from this it is not certainly clear what he himself thinks. If he calls certain opinions neither probable nor improbable, he keeps silent about his judgment concerning them. If he calls one opinion more probable, but gives no judgment about the opposite, or says of it, "I do not dare to condemn it"; "I do not dare to call it improbable," he does not therefore pronounce it practically probable, but leaves the matter to the judgment of others (Preface of St. Alphonsus, bk. V, n. 76).

(delta) If he calls some opinion truer, far, much, notably, certainly more probable, or more common and more probable, he does not hold the opposite as sufficiently founded.

(epsilon) If he calls an opinion common or more common, and gives no judgment about the opposite, the former commonly must be called his own.

Finally, if there is doubt about the doctrine of the holy Doctor, sometimes the doubt can be resolved from a comparison of different works and places.

¹ But if St. Alphonsus (I, 20) states that positive doubt is had "when for each part, or at least for one, there is a grave motive," he takes the word "doubt" in the broader sense, insofar as it includes both strict and broad doubt.

² It is better called an opinion (sententia) than an opinion (opinio), because opinio designates a state of mind.

³ Cf. De Minusprobabilismo, pp. 14-17.

⁴ An opinion which by some is called the only probable one falls into an opinion certain in the broad sense.

⁵ Denzinger-Bannwart, n. 1127.

⁶ Among grave authors St. Alphonsus counts: Suarez, Soto, Azor, Canus, Sylvius, Cajetan, Banez, Navarrus, Paludanus, Toletus, Sylvester, Lessius, Molina, Sanchez, Angelus, Vasquez, Armilla, Valentia, Layman, 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 indeed must be preferred to others (cited dissertation, loc. cit.).

⁷ This dignity, according to the doctrine of Benedict XIV, "does not pertain to doctors who have been in the Church, but to doctors of the Church itself" (De Serv. Dei beatif., etc., bk. 4, p. 2, c. 11, n. 11). For it, as the cited author teaches, there are required "eminent doctrine, notable sanctity of life... and besides this, the declaration of the Supreme Pontiff or of a General Council legitimately gathered" (loc. cit., n. 13).

⁸ It is pleasing to report some excerpts from certain ecclesiastical documents: 1. The Sacred Penitentiary on 5 July 1831 responded that a confessor is not to be disquieted who in the practice of the Sacred Penitentiary follows all the opinions of St. Alphonsus, although he does not read the works of the blessed Doctor except to know his doctrine accurately, without weighing the arguments or reasons on which the various opinions rest. Yet you should not apply these things to opinions which are sufficiently established to be opposed to declarations of the Church, or which someone, after perhaps making inquiry and taking all things into account, judges to be certainly less probable. 2. The Sacred Penitentiary on 19 Dec. 1855 responded to a certain professor that, notwithstanding his oath of following Probabiliorism and the opinions of the Probabiliorists, he could "follow and publicly hand on in all things the doctrine of St. Alphonsus de Ligorio." 3. The decree Urbis et Orbis, dated 23 March 1871, concerning the concession of the title of Doctor: "He (St. Alphonsus) dispelled and drove away the darkness of errors widely diffused by unbelievers and Jansenists, by learned works, and especially by treatments of Moral Theology. Besides this he clarified obscure things and explained doubtful ones, since among the tangled opinions of theologians, whether laxer or stricter, he paved a safe way by which the directors of the souls of the Christian faithful could walk with unoffending foot." 4. The Apostolic Letter in the form of a Brief, dated July 1871, concerning confirmation of the title of Doctor: "Intending his mind solely toward the glory of God and the spiritual salvation of men, he wrote very many books, filled with sacred learning and piety, whether amid the tangled opinions of theologians, both laxer and stricter, for fortifying a safe way by which the directors of the souls of Christ's faithful could walk with unoffending foot, or for informing and instructing the clergy." 5. Finally, the Congregations in their responses, repeatedly and expressly, referred questioners especially to the doctrine of St. Alphonsus (De Minusprobabilismo, pp. 46-48).

⁹ Nouv. Rev. theol. VII, p. 98.

¹⁰ Cf. De Minusprobabilismo, pp. 64-65.

Proposition. For acting licitly, certainty strictly so called concerning the honesty of the action to be placed here and now is required. This is clear, first, from Sacred Scripture. "But he who discerns, if he eats, is condemned, because it is not from faith. But everything that is not from faith is sin" (Rom. 14:23). Here St. Paul treats the controversy about the eating of foods which the Mosaic law prohibited. Moreover, the Apostle teaches that he sins who eats the aforesaid foods while discerning, Greek diakrinomenos, which in the context means: struggling with himself, doubting, hesitating,¹ whether the eating is licit. But according to the Apostle the reason is that every action placed without a firm persuasion concerning the honesty of the action is sinful. "It is said," says St. Alphonsus, "from faith, namely, from a certain dictate of conscience, so that a man is persuaded in his conscience that by acting he acts rightly" (I, 55). This interpretation is deduced from the context of the discourse (vv. 2, 14, 22), and even today is commonly admitted.² There is added, second, an argument taken from reason. Beyond doubt, he sins who wills and chooses an action, whether it is good or evil, whether it offends God or does not offend God. But one acts thus who wills and chooses an action about which he doubts whether here and now it is licit. Hence St. Augustine: "To do that which is uncertain whether it is a sin is a certain sin."³ St. Alphonsus asserts the same repeatedly (I, 22, 24; likewise I, 81 and Homo Apostolicus I, 65, where he teaches that not even a most probable opinion of itself and ultimately suffices).

Corollary I. Authors commonly teach that broad certainty suffices for acting licitly. But this is said less accurately; for broad certainty still admits prudent fear, or broad doubt. But it is not licit to place an action as long as one still prudently fears that it is formal sin, or a true offense against God. Moreover, this fear or broad doubt is easily excluded through some general reflex principle, for example: It is licit to follow an opinion certain in the broad sense; which principle others also call concomitant.

Corollary II. It suffices that someone in good faith be certain of the liceity of an action, even if the foundation on which the certainty rests is less solid. Nor is it required that someone reflexively judge that he is certain.

Corollary III. One who acts with a practical doubt concerning the honesty of an action commits as much and such a sin as that about which he doubts; for he perpetrates as much and such a sin as the danger to which he exposes himself (St. Alphonsus, I, 22). If only the notion of sin is apprehended, there is had a sin of unnamed species; concerning this, however, observe these words of St. Thomas: "When reason apprehends something as evil, it always apprehends it under some notion of evil; for instance because it is contrary to a divine precept, or because it is scandal, or on account of something of this kind; and then such an evil will is reduced to such a species of malice" (I-II, q. 19, a. 5, ad 3). "Yet it must be noted for practice, what many are ignorant of, that it is gravely illicit to act with a practical doubt about grave sin."⁴

¹ The source's Greek form is badly OCR'd; the intended term is diakrinomenos.

² That by "faith" supernatural faith is not understood, but a dictate of conscience, is clear from Lateran IV (c. 41); and that a certain dictate is understood is taught by Estius, Beelen, Cornely, Reithmayer, Bisping, and other interpreters commonly.

³ Bk. I, De Baptismo, c. 5.

⁴ Cf. Marc, n. 37; Vindiciae Alphonsianae, I, p. 504; Aertnys-Damen, I, n. 64.

We speak about him who lacks the conscience required for acting licitly, that is, about him who is not certain of the honesty of the action to be placed. Moreover:

I. One who is not certain of the honesty of some action, unless he wishes to abstain from it, is held before all else to inquire into the truth, that is, to investigate what the morality of the action is; in other words, what the ordinance of the eternal law concerning it is. And indeed one who neglects the aforesaid inquiry holds the divine ordinance itself cheap, since he rashly exposes himself to the danger of violating it. Hence St. Thomas: "But in doubtful and uncertain matters, reason does not give judgment without a preceding inquiry; and therefore inquiry of reason before judgment about things to be chosen is necessary; and this inquiry is called counsel" (I-II, q. 14, a. 1). And St. Alphonsus: "For acting licitly in doubtful matters we must inquire into the truth" (I, 54).

II. Concerning the manner of inquiring into the truth, hold these things:

1. The arguments, intrinsic and extrinsic, or authorities, of each opinion mutually opposed to the other, must be investigated and compared. For in doubts one part must be chosen before the other. But "choice imports a certain preceding comparison" (St. Thomas, I-II, q. 13, a. 1).

2. The inquiry must be made with moral diligence proportionate both to the person inquiring and to the gravity of the matter of which there is question, and to the time that can be spent on the inquiry. The less learned should try to reach the truth by consulting the more learned, for example a pastor or confessor; the more learned, by their own inquiry. "It will be enough," says Benedict XIV in the encyclical De Praeparatione ad Annum Universalis Iubilaei (26 Jun. 1749), "to have admonished confessors that in a doubtful matter they not rely on their own opinion; but before they decide the cause, they should consult very many books, especially those whose doctrine is more solid; and then they should descend to that opinion which reason persuades and authority confirms. Nor indeed did we teach anything else in our encyclical on usuries." Besides this, greater diligence is needed if there is question of a matter of great importance, say of notable restitution, than if the discussion concerns a small matter.

If someone, after the truth has been inquired into, continues to doubt, or is not certain of the honesty of the action, it is disputed to what extent one who thus doubts theoretically can come to practical certainty and place the action. Moreover, the diverse responses to this question constitute the diverse moral systems, about which we must now speak. But it is clear that this controversy is of the greatest importance: since a moral system governs the whole of moral doctrine and opens the way for solving for practice the innumerable doubts that occur in it. About to speak of this very grave matter, we shall set forth first the notion of a moral system, the state of the controversial question, and the diverse systems; then the proof of the system which seems true to us. Finally we shall add some points concerning certain sayings akin to the moral system, concerning the importance of the controversy between equiprobabilists and probabilists, and concerning the use of the moral system.

Kinds of Certitude.—Judgments may be certain in a greater or less degree.

(a) They are metaphysically certain, when error is absolutely impossible, the opposite of what is held by the mind being a contradiction in terms which omnipotence itself could not make true. Example: The judgments that the same, identical act cannot be both good and bad, that good is to be done and evil to be avoided, that God is to be honored, are metaphysically certain, since they result immediately from the very concepts of being, of goodness, and of God.

(b) Judgments are physically certain, when error is impossible according to the laws of nature, the opposite of what is held by the mind being unrealizable except through intervention of another cause. Example: The judgments that he who takes poison will destroy life, that he who applies fire to a house will destroy property, are physically certain. because natural agencies, like poison and fire, act infallibly when applied to suitable matters and under suitable conditions and left to their course, unless they are overruled by superior power.

(c) Judgments are morally certain, when error is impossible according to what is customary among mankind, the opposite of what is held by the mind being so unlikely that it would be imprudent to be moved by it. Examples: One is morally certain that what a reputedly truthful and competent person relates to one is true. A person is morally certain that a conclusion he has drawn about his duty in a particular instance is correct, if he believes that he has overlooked no means of reaching the truth. Testimony and inference, since they come from free and fallible agencies, may lead into error; but, when they appear to have the requisite qualities indicative of truth, they are for the most part reliable and in practical life have to be considered as such.

As to the certainty that is required in the judgment of conscience, the following points must be noted:

(a) Metaphysical certainty is not required, since conscience does not deal with primary propositions, but with deductions about particular acts. The first moral principles, which are the object of synderesis, and at least some of the general conclusions, which are the object of moral science, are metaphysically certain (see above 145, 300), as they are based on necessary relations; but the particular conclusions, which are the object of conscience, are concerned with the contingent and the individual.

(b) Physical certainty is not required for the judgment of conscience, since conscience is not concerned with the activities of natural agents, but with the activities of moral agents that act with freedom and responsibility.

(c) Moral certitude, therefore, is sufficient for the conclusions drawn by conscience. That a higher kind of certitude is not necessary should not surprise us, for it would be unreasonable to expect that the same degree of assent be given to judgments that are concerned with particular and contingent cases as to those that are concerned with universal and necessary principles.

Moral certitude is of two kinds: (a) certitude in the strict sense, which excludes not only the fear of error, but every doubt, prudent and imprudent, great and small, Example: Titus thinks of a way in which he could easily make money dishonestly; but his conscience sees that the thing is manifestly wrong and decides without the slightest fear or doubt that it must not be done; (b) certitude in the wide sense, which excludes all fear of error and every serious or prudent doubt, but not one or other slight and imprudent doubt. Example: Caius was baptized by an excellent priest, but the date was omitted in the register. The doubt occurs to Caius that perhaps something essential was also omitted, and that it may be his duty to seek another Baptism. His doubt is unreasonable.

Moral certitude in the wide sense is sufficient for a safe conscience, even in matters of great importance, since it is frequently the only kind of certitude one can have, and he who would strive to be free from every slight and baseless suspicion would be soon involved in a maze of scruples and perplexities. Example: If the Caius above referred to were to yield to his doubt and be rebaptized, a similar doubt about the second Baptism might easily arise in his mind, and he would be no more contented than before.

From the point of view of its object, certitude is twofold. (a) Speculative certitude refers to a judgment considered as a general law, abstraction being made from particular circumstances. Example: It is speculatively certain that farm work on a holyday is a forbidden kind of work, and that clerics are obliged to say the Divine Office. (b) Practical certitude refers to a judgment which is an application of a general law to a particular case, consideration being given to all the pertinent circumstances. Example: It is practically certain that Titus may make hay on a holyday, if otherwise he will suffer great loss; and that a cleric is excused from the Divine Office, if his physician has warned him that he is physically or mentally unable to perform it.

Speculative certainty is not sufficient for conscience, but practical certitude is required, since conscience refers not to abstract laws but to concrete cases—not to what is right if only the object of the act is considered, but to what is right when one considers the object, the motive, and all the circumstances here and now present.

From the point of view of the arguments on which it is based, certitude is of two kinds. (a) Demonstrative certitude is the assent that rests on a conclusion logically drawn from certainly true premises. Example: Caius argues that he is obliged to go to Mass on Sunday, because the law is certain, and it is also certain that the law applies to him. (b) Probable certitude, which is the assent that rests on a conclusion, whose premises, though not certain, seem to be true, and against which there is no counter conclusion, or none that cannot be readily answered (see 703). Example: Caius is pretty sure that he is seriously ill, because he perceives a number of alarming symptoms; the possibility that these may be due to imagination is excluded by the fact that they are new and sudden. Caius, therefore, concludes that he may hold himself excused from attendance at Mass.

Probable certitude is sufficient for conscience, for in moral matters it is impossible to have at all times reasons that amount to a demonstration, and hence a person acts prudently in following a decision that is solidly probable and unopposed by any contrary serious probability. What is called “probable certitude” here is very different from probable opinion, about which there will be question below (662 sqq.)

From the point of view of the manner in which it is obtained, certitude is again twofold. (a) Direct certitude is that which is obtained from principles that are intrinsic to the case by applying to the matter the law concerning it. Examples: A judge who decides according to the evidence and proofs given in court that an accused is guilty, and a son who concludes from the Fourth Commandment that he is bound to help his parents in necessity, have direct certainty in their judgments, because they argued from principles that deal with the question before them. (b) Indirect certitude is that which is obtained from principles that are extrinsic to the case by applying to the matter in hand reflex principles (i.e., rules that direct how one should act in doubt) or the principle of authority (i.e., the argument drawn from the opinion of those who are acknowledged as competent to decide). Examples; If a judge is not able to form a certain judgment from intrinsic reasons concerning an accused, because strong arguments have been given both for guilt and for innocence, he has recourse to principles that have reference to his own state of doubt, and which declare that he must acquit when he is not certain of guilt. If a man is not able to decide whether the Fourth Commandment obliges him to keep his grandparents or mother-in-law in his home, when they upset his family and are able to take care of themselves, he can have recourse to the external principle of authority by consulting his confessor.

Direct certitude is not necessary for the judgment of conscience, for often, as in the cases just mentioned, it is not possible. Moreover, indirect certitude suffices to give one who is in doubt such practical assurance that one’s fears become unimportant and one is able to act prudently in spite of them.

(a) The principle of authority—that “in doubt we can safely follow the advice of those who are experts and truthful”—is reliable, as both the conditions required for authority (viz., knowledge and truthfulness) and also daily experience show.

(b) Reflex principles likewise, although they do not prove what is deduced from them, are well founded, and point so clearly the side to be taken when judgment is suspended between alternatives that they enable one to act with all the certitude that prudence demands. Example: The principle that “in doubt decision should be given in favor of the accused,” is based on the fact that a man’s right to his life and liberty is so certain that he does not forfeit that right unless it is proved convincingly that he is guilty.

Examples of uncertain and certain consciences are the following:

(a) Uncertain conscience: It is lawful to make a just contract (major premise certain); but this contract is just (minor premise a matter of doubt or opinion); therefore, this contract is lawful (conclusion a matter of doubt or opinion).

(b) Conscience directly certain: It is lawful to make a just contract (certain); but this contract is just (certain); therefore, I may make this contract (certain).

(c) Conscience indirectly certain: It is lawful to follow competent advice or a moral system approved by the Church (certain); but a competent spiritual adviser or an approved system of Moral Theology holds that this kind of contract is lawful (certain); therefore, it is lawful for me to make this contract (certain).

Necessity of Certitude.—Prudence, being an intellectual virtue, must have certainty (see on the Certain Conscience, 640 sqq.). But with regard to particular contingencies (e.g., whether Balbus ought to marry Caia) there are various kinds of certainty.

(a) There is the certainty of knowledge based on a generalization from experience of what happens in the majority of cases (e.g., that persons well mated by reason of birth, age, dispositions, etc., marry successfully). This kind of certainty belongs to moral science.

(b) There is also a certainty of knowledge based on the indications in a particular case (e.g., that Balbus and Caia appear to have congenial dispositions and a mutual affection that will make their marriage a success). This is the certainty of opinion, and while it may suffice as a rule for conscience (see the Systems of Conscience, 672 sqq.), events do not always verify its predictions. Hence it is said: “The thoughts of mortal men are fearful and our counsels uncertain” (Wis., ix. 14).

(c) There is finally the certainty of practical truth, which consists in harmony with a good will. This is the certainty that is proper to prudence, for this virtue is not a matter of reason alone. Hence, even though a matter properly decided on should not take place or should fail of the purpose intended (e.g., if the marriage of Balbus and Caia is prevented or turns out badly), it remains that prudence was not deceived in its decision, for that decision when made was according to right reason and a good will (see 578).

What are the divisions of moral conscience? - If in that syllogism which must be formed in order that conscience may be had, the major proposition, or law, always stood with evident certainty, and the minor proposition, or that this or that action is contained in the law, also always stood with evident certainty, there would be only one conscience, certain and right conscience. But since both the law and the application of the law often must be gathered by the force of difficult reasoning, hence there are various species of conscience.

Therefore it is divided: 1. Into right and erroneous conscience. Right conscience is that which dictates what is true; erroneous, that which dictates as true what is false. Erroneous conscience is either vincibly or invincibly such, according as the error morally could and ought to have been avoided, or morally could not have been avoided. 2. Into certain, probable, doubtful, strict, lax, and scrupulous conscience, according as it is founded on a certain, probable, doubtful, stricter, laxer, or altogether empty motive. Conscience only subjectively certain, namely one which is thought to be such, and therefore with certainty taken more broadly, as also probable and doubtful conscience, can be objectively right or erroneous. But scrupulous, strict, and lax are brought back to erroneous conscience. For without sufficient reason, the scrupulous conscience fears sin where there is no sin; the lax bends judgment in favor of liberty, either to avoid the law simply, or to lessen its obligation; but the strict affirms either an obligation which is not present, or one more grave than actually exists. Suarez t. 3. d. 12. s. 2;

S. Th. 1. 2. q. 19. a. 3, a. 6 ad 2, Quodl. 3. a. 26.

What is certain conscience; and what is its directive force? - Certain conscience properly is that conscience which rests upon a certain motive; and consequently judges concerning the honorableness or shamefulness of the action to be done without fear of erring. Less properly, however, it is that which judges simply without any fear of erring concerning the honorableness or shamefulness of an action. This latter is only subjectively certain; the former is also objectively certain. It can likewise be certain strictly and broadly, or morally. Strictly certain excludes every doubt, both prudent and imprudent. Broadly or morally certain excludes only every prudent doubt. Its directive force is declared by the following propositions.

It is unlawful to act without conscience subjectively certain concerning the honorableness of the action. - Proof. He who acts without this conscience wills an action concerning whose honorableness or shamefulness he is uncertain. But to will an action concerning whose honorableness or shamefulness someone is uncertain is nothing other than to will it whether it is good or evil. But again, to will an action whether it is good or evil is illicit; for this is a will consenting to evil. Therefore. S. Th. 1. 2. q. 19. a. 3. 5, Quodl. 3. a. 27 ad 2, Quodl. 8. a. 13; L. 1. 1. n. 3; Suarez tr. 3. d. 12. s. 3; E. M.

Note: 1. "That diverse species of probabilities are given.... A tenuously probable opinion is one which rests on some foundation, but not such as avails to draw to itself the assent of a prudent man.... Probable is that which rests on a grave moment, either of intrinsic reason or extrinsic authority, which avails to draw to itself the assent of a prudent man, although with fear of the opposite. More probable is that which rests on a graver foundation, but still with prudent fear of the opposite, so that the contrary is also judged probable. Most probable is that which rests on a most grave foundation, and for this reason the opposite is judged either tenuously or doubtfully probable.... An opinion or sentence morally certain is one which excludes every prudent fear of falsity, so that the opposite is reputed altogether improbable. Finally a safe opinion is one which withdraws from every danger of sinning; but the safer is one which withdraws more from such danger, although it may not rest on stronger reasons." L. l. c. But S. D. speaks more exactly about a most probable opinion, H. A. tr. 1. n. 65: "Unless we wish to confuse a most probable opinion with an absolutely certain opinion, it is necessary to say that the opinion contrary to the most probable is not tenuously probable, but doubtfully probable." The reason is that a most probable opinion "is within the limits of probability," and therefore "does not exclude every prudent fear." "But tenuous probability is not true probability, and therefore does not bring with it a prudent reason. But doubtful probability brings some prudent reason, although not altogether certain and stable." Cf. also Op. Mor. l. 1. n. 85. But lest there be quibbling about words, as far as concerns us, we recognize no opinions, as regards doctrine, within the limits of true probability except the probable opinion, the more probable, and the most probable. Below the probable there is only the non-probable, the improbable, of which there can indeed be various grades; above the most probable there is only the certain. The probable is immediately opposed, by an opposition of comparison, to the more probable; but mediately to the most probable; and likewise the most probable is immediately opposed to the more probable, but mediately to the probable, unless someone wishes really to confuse the most probable with the certain.

2. Various moral systems: Tutiorism: A moral system which establishes that in doubt the safer part is to be followed practically. One kind is absolute, and is Rigorism, which establishes that the safer part must always be followed. Another is mitigated, which establishes that the safer part must be followed unless the other part favoring liberty is most probable. Probabiliorism: It is a moral system which establishes that it is licit to follow an opinion favoring liberty only when it is more probable than the opposite favoring the law. Therefore according to this system a doubtful law obliges, against the most common opinion and against reason. Equiprobabilism: It is a moral system which establishes that it is not licit to follow the less safe opinion unless it is equally or almost equally probable as the opposite. It is indeed a right norm of acting, but not to the exclusion of probabilism, which is a moral system containing an altogether right norm of acting, embracing all the cases of a true probable opinion favoring liberty, when the question concerns merely the subjective honorableness of an action. Probabilism: It is a moral system which establishes that it is licit to follow a truly probable opinion favoring liberty, although the opposite in favor of the law is more probable, whether a little or much more probable, where nevertheless the question concerns only the liceity of a human action. The reason is that when there is a truly probable opinion against a law, the law is doubtful, and a doubtful law does not oblige. Laxism: It is a moral system which establishes that it is licit to follow an opinion even doubtfully and tenuously probable against the law. It was condemned by Innocent XI, proposition 3, condemned March 2, 1679.

With a practically probable conscience, which proximately directs the action really to be placed here and now, it is altogether unlawful to operate. - For only a subjectively certain conscience is the rule of morals. And in this sense that saying is consequently false: He who acts probably, acts prudently. L. 1. 1. n. 58. 69. 80. Therefore the whole question here concerns a speculatively probable conscience, which only remotely directs the action, stating the probable existence of a law: namely whether by means of some reasoning we can lawfully make the step from a speculatively probable conscience to a practically certain conscience, or, what is the same, whether, while a probable opinion stands concerning the honorableness of some action in general, we can form for ourselves a certain conscience concerning the honorableness of such an action in a particular and individual case, and thus licitly follow in practice a speculatively probable opinion. To resolve this question we establish the following propositions.

As regards the first, the holy Doctor refers himself back to those things which were said at the beginning. At the beginning, n. 31, these things are had: "But whether it is licit to operate with a probable opinion, there are three opinions, the first of which is that someone can licitly follow an opinion even less probable in favor of liberty, although the opinion in favor of the law is certainly more probable. Authors of the past century held this opinion almost commonly, but we say that it is lax and cannot licitly be embraced. The reason is that when the opinion in favor of the law is certainly more probable, then the law is no longer doubtful by a strict doubt, as happens, as we shall explain later, when the opinions both in favor of the law and in favor of liberty are equally probable; but it is morally certain, since it has in its favor a certain foundation that it is true, whereas on the contrary the less probable opinion, which favors liberty, has such a foundation that it is not true, so that it remains tenuously, or at least doubtfully, probable before the safer opinion; and therefore it is not prudence, but imprudence, to wish to follow it. For when it certainly appears to the intellect that the truth stands more for the law than for liberty, then the will cannot prudently and without fault follow the less safe part: for then it would not operate from its own judgment, or its own belief, but from a certain effort which by its will it will make upon the intellect, removing it from that part which seems truer to it, and bending it toward that part which not only seems to it not true, but does not even show that it has a certain foundation by which it could be true."

Now from these things it is openly clear that S. D. by an opinion certainly more probable really understands an opinion morally certain. For he says that then the law 1. is not doubtful by a strict doubt, but is morally certain; 2. that the same law then has in its favor a certain foundation that it is true; 3. again, that the said law has against itself only an opinion which has such a foundation that it is not true; 4. that the less probable opinion opposed to the law is tenuously or doubtfully probable; so that it is imprudence to wish to follow it, and that it not only seems not true, but does not even show that it has a certain foundation by which it could be true.

Now a tenuously probable opinion is not a truly probable opinion; and the same S. Alph. teaches this, n. 65: "tenuous probability is not true probability, but is only a certain false or vain appearance of probability." Likewise a doubtfully probable opinion is not truly and properly probable, which we contend it is licit to follow even in concurrence with the more probable. For if it is doubtfully probable, it participates in the nature of doubtful probability, and therefore properly speaking is not probable. And certainly a truly and properly probable opinion is defined by the same S. Alph., l. c. n. 21, as "that which rests on some grave foundation apt to incline the assent of a prudent man." Therefore a doubtfully probable opinion will be an opinion which has a doubtfully grave foundation, and therefore does not merit the assent of a prudent man, who would be exposed to the danger of acting imprudently. "Doubtfully probable," says S. Alph. l. c. n. 65, "which no one can follow, but if it is not probable, it has only some prudent reason that it is true... the doubtfully probable has some prudent reason, although not altogether stable, that it is probable."

And hence it is clear that that opinion which it is imprudence to wish to follow, and which not only seems not true, but does not even show that it has a certain foundation by which it could be true, is not a truly and properly probable opinion. Therefore if the less probable opinion opposed to the certainly more probable is not truly and properly probable, the certainly more probable opinion by no means remains within the limits of probability, but already reaches certainty. The same is confirmed from the Dissertation inserted in Op. Mor. l. 1. n. 55 of the sixth and seventh editions, and related in the edition of P. Gaude p. 25 as a commentary on the doctrine of S. Alphonsus in the text, and in the Turin edition of 1846, where he thus explains that phrase "certainly more probable." "I said," he says, "certainly more probable, because when the opinion in favor of the law is certainly and without any hesitation more probable, then that opinion cannot be anything except notably more probable. And in that case the safer opinion will no longer be doubtful (understand concerning doubt strictly taken... Cf. here 138), but is morally or quasi morally certain; at least it can no longer be called strictly doubtful, since it has in its favor a certain foundation that it is true. Hence then it happens that the less safe opinion, which lacks a certain foundation, remains either tenuously or at least doubtfully probable with respect to the safer; and therefore it is not prudence, but imprudence, to wish to embrace it," etc.

Note first that from S. D., if an opinion is certainly more probable, it is notably more probable, because a small excess either is not perceived by the intellect, or is not perceived without fear of erring. Hence, if an opinion is certainly more probable, it is also notably more probable. - Then note as regards that phrase, quasi morally certain, that to the holy Doctor in this matter, where the question concerns a certain moral estimation, a little is reputed as nothing. Moreover S. D. is not speaking of any probability whatever, but of that which appears certainly to the intellect, and he is speaking of one who, if he departed from this probability, would depart from his own judgment through a certain effort of the will, and would act against his conscience; to whom he therefore applies that saying of the Apostle, Rom. 14:23: What is not from faith is sin. Ibid. and H. A. tr. 1. n. 31. Finally S. D. calls that opinion lax which defends even a less probable opinion in favor of liberty without any distinction, namely one which has only some foundation of reason and authority; and therefore he distinguished by saying that someone cannot follow this less safe opinion when there is a great and certain preponderance in favor of the safer. Apolog. cont. il P. Patuzzi anno 1765. But the true doctrine of probabilism, which we follow, does not defend any probable opinion indiscriminately, but one certainly and gravely probable, which alone is truly probable. Likewise S. D. calls that doctrine lax which authors of the past century almost commonly handed down, namely in the latter part of that century, in which several lax opinions of probabilists were condemned by the Holy See; but certainly not Sanchez, Suarez, Lessius, Palaus, Laymann, Lugo, Pallavicini and very many others, whom S. Alph. himself, not only in his Moral Works, but in that very Dissertation on his moral system, approves and praises for his opinion. He himself defends this and repeatedly champions it, not against probabilists, but against rigid tutiorists, and affirms that for a series of many years it had without doubt been common among all. Breve Dissertaz. dell'uso moderato dell'Opin. Probab., Naples 1762, p. 48; Op. Mor. l. 1. n. 59. 68-73. 84.

As regards the other point, it is an evident thing that if S. D. by an opinion much more probable understands an opinion morally certain, or quasi morally certain against a tenuous or doubtful probability, by an opinion a little more probable he understands simply an excess of mere probability. For otherwise the holy Doctor himself could certainly not admit that a probable opinion can sometimes retain its probability and that someone can follow it, although the opposite is notably more probable, as he himself really admits several times. Cf. Comment. de Consc. et de Probabilismo n. 104 seq. But if it is asked why S. D. then designates that excess by saying "a little more probable," and not simply by saying "more probable," the reason is that S. D. considers the matter practically rather than speculatively, given the nature of the thing and the principles, and also the rigor of words, and thus distinguishes between a small and a notable excess of probability. A notable excess, truly such, of probability is had when it is evident and certain; and then, from S. D., probability reaches certainty. And this is indeed so, at least practically and regularly speaking; for such probability, at least practically, is confused with moral certainty, which in a certain broader sense is certainty. And in fact S. D. is speaking of a much greater probability that is certainly and evidently such. Certainly and evidently to whom? Not only certainly to the one opining, since all know well that one and the same opinion appears less probable to one and more probable to another, indeed even to the same person in diverse circumstances; but to all, or by the common judgment of the wise. And in fact if a proposition is much more probable certainly and evidently to all, or by the common judgment of the wise, it already really is, practically speaking, morally certain. For in things to be done we often use most probable and more probable opinions as though true, and as though morally certain, when greater certainty cannot be had. Every other excess, although perhaps notable, nevertheless if it is not so evident and certain, really cannot properly be called notable, since then there is doubt concerning such a notable excess, and the proposition which to one seems much more probable to another perhaps, indeed perhaps even to the same person, the matter having been weighed better, as S. Alph. himself confesses of himself, l. 1. n. 86, H. A. tr. 1. n. 78, appears much less probable. Therefore, if that notable excess of probability is so evident and certain, then it already reaches certainty, and by right and deservedly the opposite can only be tenuously or doubtfully probable. But if, although notable, it nevertheless is not so evident and certain, that excess really cannot as regards us be held as notable, but remains within the limits of equal probability or of a little greater probability. Certainly, if to the one opining alone a sentence seems notably more probable, or if doctors fall into various opinions concerning it, can it prudently be held as certainly and evidently more probable? Certainly not. Hence again it is clear that by that "a little greater" excess S. D. really understands simply an excess of probability.

Not only to the one opining. "Such an appearance (of greater probability)," says S. D., "cannot constitute a certain rule of operating, since it can deceive in many ways. For not rarely some opinion which will appear more probable to someone will appear less probable to another; indeed to the same person an opinion which yesterday was less probable will today appear more probable." Therefore that opinion which appears more probable to someone cannot be a true rule of acting, because "the law would be particular only for him to whom that opinion appears more probable. But this would certainly be against the nature of law, which for the common good must necessarily be universal and universally proposed, lest the people, who are bound to observe it, be frequently divided and perplexed concerning the truth to be embraced, while each preacher or confessor, from the diversity of opinions and according to his own sense, would often instruct the faithful." Nor is it of force to say that by following the benign sentence (namely the probable even in concurrence with the more probable in favor of the law), disparity can also intervene, since the same opinion can seem probable to one, improbable to another. It is not denied that this can happen; but it will always be true that, when some opinion is strong with solid probability and rests on a certainly grave foundation, it will be regarded as probable among the greatest part of the wise. And this will already be enough to preserve the universal uniformity of observance of the law, notwithstanding that among some particular person that opinion is not probable; for that which happens rarely does not take away universal conformity. Yet this does not happen concerning the estimation of more probable opinions, because since greater or lesser probability depends on moral motives, namely on the judgment and weighing of reasons, which some draw from one principle, others from another, it happens not rarely but commonly that what appears stronger to one appears weaker to another.... But that we become certain that some opinion... is truly more probable or has the required preponderance, this is morally impossible. For either that preponderance is small, and who will be secure that the opinion is truly more probable? For since the excess is moderate, it can with difficulty be perceived certainly. Or the preponderance is great, and who will be able to judge that it reaches a sufficient measure, so that the opposite is judged false or tenuously probable? And thus we would always have to act with practical doubt. Either I am bound to follow opinions more probable in themselves, and then when shall I know which opinion is truly more probable in so many cases, where grave reasons and authorities occur opposed on each side? Or opinions more probable to me, and the straits would be increased; for often I would have to judge my opinion to be probable against another opinion of several wise men. And then who will render me safe that my opinion is certainly more probable and more notable, with that notable preponderance which some of the adversaries require? How shall I become certain that I have understood the opposed reasons well and solved them well? that the dictate of conscience which I have formed for myself is sufficiently certain and safe? that I have not been deceived by my own sense, so that if I err, my error is truly invincible and inculpable?" S. Alph. Dissertation anno 1755, n. 3. 17. 42. 43. 48. 50.

And if it is asked why S. D. made this distinction between a little more probable and notably, much, evidently, certainly more probable, the reason is that S. D., as is clear from l. c. H. A. n. 31 and from the Apologia contra Patuzzi 1762, wished to oppose himself to those probabilists who extended probabilism even to tenuous and doubtful probability, and therefore contended that it is licit to act when any apparent reason is present, but not firm reason, or authority. Hence from the opposite S. D. established that someone must then follow the opinion certainly, evidently, notably, much more probable, which, as is clear, in comparison with the tenuously or doubtfully probable is by right and deservedly called morally certain by S. D. Therefore, since S. Alph. designated such an opinion in comparison with the doubtfully and tenuously probable by "notably more probable," what remained was that he designate any other more probable opinion in comparison with the truly probable by "a little more probable." Cf. Breve Dissertaz. etc. cited above at the end of n. 133, p. 51, Op. Mor. ed. Rome 1757, l. 1. n. 33. Behold the words of S. D. in the Apology of the year 1765: "I did not contend nor do I contend to found new systems, and I know well that no probabilist of solid doctrine hands down as licit the use of a tenuously or doubtfully probable opinion. But because many probabilists without distinction say that it is licit to follow a less probable opinion when it has some foundation from reason or from authority, therefore I wished to distinguish, establishing that it is not licit to follow the less safe opinion when the excess of probability in favor of the safer is notable and certain, because then the less safe opinion cannot be called certainly probable."

39. • DEFINITION. Certain conscience is that by which someone firmly and without fear of erring judges that something is good or evil.

DIVISION. Certitude is usually distinguished as threefold:

1. Metaphysical, which belongs to those propositions in which the attribute belongs essentially to the subject, and therefore is immutable.

2. Physical, which is founded on the constant order by which the world is ruled; this stands firm as long as physical laws are constant, and are considered to have been constant.

3. Moral, which rests upon the laws by which men are ruled in their acts.

Again moral certitude is subdivided into perfect and imperfect. The former is that which is so founded on moral laws that it is clearly perceived that the proposition cannot be false. This is mediately reduced to metaphysical certitude. The latter is that which belongs to those propositions in which it is not absolutely repugnant for error to be present, although it could happen only with the greatest difficulty. This admits various degrees.

Likewise some certitude is direct, which is obtained through certain arguments intrinsic to the matter; another is indirect, which is had from some extrinsic principle, for example, the authority of the Church.

Principles. - I. Certain conscience alone is the right rule of morals. The reason is 1. because everything which is not from faith is sin. Rom. 14. 23; 2. because one acting with a conscience not certain violates the obligation of inquiring into the truth, and therefore sins formally ¹.

¹ Namely, precepts oblige us not only not knowingly to violate them, but also not to transgress them through negligence in inquiring. And from this is the guilt of him who acts while doubting about the honesty of the act. Concerning this matter Suarez (On Censures, disp. 40, sect. 5, no. 12): As long as man does not do what is in him to lay aside doubt, whatever of danger there is in such an operation is imputed to him; for the ignorance which intervenes there is vincible, and therefore cannot excuse from fault. Hence not even he is immune from this fault who, while acting rashly, embraces that part which agrees with the right norm of acting.

II. Morally certain conscience, even imperfect, suffices. The reason is 1. because one acting with such a conscience truly acts from faith; - 2. because absolute certitude often cannot be had; - 3. because it is clear from the common opinion of the Doctors and from universal practice ².

² Whatever is lacking in a plainly firm certitude in the case is always supplied through reflex principles, as will soon be said where probable opinion is treated. For otherwise certitude concerning the honesty of the action must be firm, as below it will occur to note concerning the theories of the probabiliorists.

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.

St. Thomas, IV Sent., d. 21, q. 2, a. 3; Quodlibet VIII, q. 16, a. 13.

213. Notions. - Conscience must also be certain. Now by reason of the subject, that is, on the part of the act, assent, or adherence to the object, conscience is either certain if its judgment adheres firmly to something, or uncertain if it does not adhere firmly; and the latter is doubtful if it does not adhere but judgment is suspended, or opinionative if it adheres but with fear of the opposite. Certain conscience, therefore, is that which formally in itself and in all the principles from which it is formed excludes fear of the opposite, and therefore firmly and without fear of erring judges that something in particular is licit or illicit.

Now we ask whether conscience, in order that it be the rule of acting, must be certain.

214. Principle. The only legitimate rule of acting is certain conscience, by which, namely, man prudently forms for himself a certain judgment that the action to be placed here and now is placed licitly and honorably; hence such conscience is required for operating licitly.

It is proved: 1) from the Scriptures, Rom. XIV, 23: Everything that is not from faith is sin; but he who is uncertain does not act from conviction, and therefore what is done from uncertain conscience is not from faith or persuasion; therefore it is sin. The Apostle explicitly states this conclusion, inferring it from the said principle: He who distinguishes (that is, who hesitates or doubts whether it is licit to eat some food), if he eats, is condemned, because not from faith. Hence Eccli. XXXVII, 20: Before all works let a true word go before you, and before every act stable counsel.

2. By reason: a) he who acts with uncertain conscience has a reasonable and founded fear concerning the malice, and uncertainty concerning the goodness, of his act. But he who is uncertain concerning the goodness of his act and nevertheless acts, wills to place it whether it be against the law or not, and thus hypothetically consents to evil, and has an evil will, and contemns the law of God and acts badly. This is confirmed by the example of a servant who, doubting whether something is against the will of his master, would neglect to inquire into the will of his master if he could and nevertheless would act: he would be judged guilty by all. Likewise, one who would do that which he suspects offends a friend would be judged by this very fact to offend him and contemn his friendship.

b) He who voluntarily exposes himself to the proximate danger of sinning formally and offending God acts badly. But he who says, "It is uncertain whether this is really evil," and acts, operates rashly because he does what he fears offends God, and thus exposes himself to the proximate danger of sinning formally and offending God. Therefore he acts badly. Hence Augustine against the Donatists: "To receive (Baptism) in the party of Donatus... if it is uncertain whether it is a sin, who would doubt that it is a certain sin?"

1. Book De Baptismo contra Donatistas, c. 5. - Several theologians call the value of this argument into doubt. Nevertheless, to one considering it well, it will appear that it does not substantially differ from the preceding argument; but the special mode of proposing it is already found in St. Thomas (Quodlibet VIII, a. 13), in the case proposed in which someone "is led into a certain doubt from contrariety of opinions..., if, while such doubt remains, he has several benefices, he commits himself to danger, and thus without doubt sins, as loving a temporal benefice more than his own salvation." In the same way in IV Sent. d. 21, q. 2, a. 3: "He who commits or omits something in which he doubts there is mortal sin, commits himself to danger." Likewise in Scotus, q. 2, prologue, and in IV Sent. d. 30, q. 1; and in St. Alphonsus, Theologia Moralis, l. 1, n. 22.

c) Conscience is the rule and measure of our acts. But a measure cannot be ambiguous, but must be certain. Therefore conscience must be certain.

215. Applications. - From the foregoing it follows:

1. That one who does not have a certain practical judgment concerning the liceity of an action, or certain conscience, cannot act; and if he must act altogether, he is bound to do what is safer, namely, what favors the law (or obligation) more and removes him more from the danger of acting badly. Hence the axiom: In practical doubts the safer way is to be chosen.

2. That one who does not have a direct, speculative-practical, certain judgment concerning the objective and material honesty of the action does not for that reason always lack a certain practical judgment concerning its subjective and formal honesty, but sometimes has a certain conscience from a certain higher principle and from a reflex judgment of the intellect reflecting upon its own act and applying that principle; for example, although the morality of such an action is doubtful to me, it is certain to me that I must place it if a superior commands it, both because presumption stands for the superior, who therefore is not to be deprived, on account of the doubt of subjects, of his right of commanding, which he certainly holds, and because the right order of the common good forbids subjects to deny obedience unless it certainly appears that the superior abuses his power; although I doubt whether such a work is servile, it is certain that I can exercise it if the pastor has said so; although in itself it is uncertain whether a sacrament is validly and licitly ministered in such matter, it is certain to me that regularly, out of reverence toward the sacrament, I must abstain from such ministration, and in a case of necessity employ it; although such a man is probably guilty, it is certain that he cannot be condemned by a judge unless he is proved guilty with certainty, etc., for there are many similar cases as is determined in the special treatises.

3. Especially, that a practical judgment is held as certain, even while speculative doubt remains, and a certain conscience of special obligation arises whenever there is present a certain and absolute obligation of obtaining a determined end which otherwise perhaps would not be obtained; in other words, whenever a good effect (for example, salvation, a sacrament, health) must be absolutely obtained, or an evil effect (damnation, death, harm) must be absolutely avoided, and there is doubt not only about the honesty but also about the necessity or efficacy of the means required for this and about the validity of the act or fact. Then, namely, a certain higher law intervenes, which dictates that in doubts concerning the validity of an act to be placed, the safer thing must be done. From this reflex judgment an objectively uncertain obligation becomes subjectively certain. The reason is that, if the honesty of an action depends upon our reason and conscience, the value of the action or the averting of harm does not in the same way; for our doubt or judgment is not able to change the nature of things, nor therefore to render a null act valid, or to bring it about that the due effect arises from the action, or to impede harm from following from it; for example, a doubt or an opinion, however probable, cannot bring it about that what is not a sacrament be a sacrament, or that what is rather poison be medicine. Hence in the case a certain natural law prohibits exposing oneself to the danger of not obtaining the end or of bringing in evil, namely, by employing a means which perhaps is ineffective or harmful. To expose oneself to a danger of this sort, in species, is especially illicit in doubts concerning things necessary by necessity of means to eternal salvation: namely, in these things one must especially act more safely and more certainly.

1. Let it be noted that one thing is necessary by necessity of means, another by necessity of precept alone: the latter is only necessary for the end because it has been prescribed, for example, hearing Mass; the former is necessary because it is a means without which the end cannot be obtained, for example, Baptism or contrition for sins.

4. That one who is uncertain, not indeed concerning the value of the act or the necessity of the means, but concerning only its honesty or only the necessity of a precept, must, before he can act, lay aside the doubt either by inquiring into the truth more diligently or by consulting the more learned, and form for himself a certain conscience concerning the honesty of the action, at least indirectly from a reflex judgment applying some general certain principle. Prudence teaches how this can be done in various cases and doubts, all the circumstances being considered, and therefore it will be explained in the treatise on prudence. But if such means here and now are lacking, he must abstain from the action; or if he absolutely cannot suspend it, he must choose what is safer, as was already said above in 1).

83. Notions. - By reason of the subject, i.e., on the part of the act, assent, or adhesion to the object, conscience is certain if its judgment adheres firmly to something, doubtful if judgment is suspended, or opinative if it adheres to something not firmly but with fear of the opposite.

Thus certain conscience, as we have already said, is that which with firm assent and without fear of erring judges something in particular to be licit or illicit.

Opinative conscience is that which judges, not firmly but with grave fear of erring, that some action to be placed here and now is licit or illicit.

Doubtful conscience is that which remains suspended and does not give assent, and therefore judges nothing concerning the licitness of an action in particular to be placed here and now: this happens either on account of a defect of grave reasons, and then it is negatively doubtful; or on account of the equality of grave reasons, and then it is positively doubtful. Whence it is not properly conscience, because it is not a judgment, but rather is the absence of conscience; nevertheless it is called conscience reductively, just as privations are reduced to that of which they are privations: in that way omission is called a human act.1

Just as, on the part of the object, judgment is divided into speculative, speculatively practical, and practically practical (I, n. 200), so there is given:

1. Merely speculative doubt concerning the truth of a thing, for example whether Baptism is valid in rose-water.

2. Speculatively or remotely practical doubt concerning the objective and material honesty of an act in general and in the abstract, or concerning something pertaining to it, for example whether Baptism in rose-water is licit; and this is twofold:

a) Doubt of law, which is concerned with law as in the proposed example: whether concerning the existence of a law or obligation, such as rights, offices, and their conditions, causes, force, nature, object, extension, limits, etc.; or concerning the cessation of a law or obligation;

b) Doubt of fact, which is concerned with fact, not indeed in itself (for then it would be merely speculative doubt and in no way would pertain to practice), but insofar as it founds some right or some obligation and thus remotely pertains to law, for example whether someone has made a vow, whether there is no other water besides rose-water.

3. Practically or proximately practical doubt concerning the subjective and formal honesty of an act in particular to be placed here and now, for example whether it is licit here and now to baptize this child in rose-water: this alone is doubt of conscience.¹

¹ Several say that it is a judgment, expressed or at least tacit, concerning uncertainty, by which we reflexively affirm that our judgment, on account of the equality of reasons, must be suspended. This indeed can happen, while we reflect concerning the state of the intellect; but doubtful conscience does not necessarily include such a reflex judgment by which we affirm that we doubt. Besides, this judgment is not conscience, because it is not a judgment definitively applying science to a particular act or fact.

Only a certain conscience is the rule of acting prudently; hence it is asked how, by force of an indirect principle, a sufficiently certain conscience may be formed so that it may be a rule of acting prudently, and how conscience negatively doubtful - positively doubtful - and opinative may be laid aside and reformed.

1. Several authors, distinguishing speculatively doubtful conscience and practically doubtful conscience, say that with the former we act licitly, but not so with the latter. But the manner of speaking, although from the seventeenth century onward it is commonly employed, even by St. Alphonsus (Th. M., book I, nn. 20, 21, 22, 25), nevertheless is not to be approved. For conscience essentially is an act, namely, a practically practical judgment; but it is impossible that the same act or the same judgment be at once practical and speculative, certain and uncertain; whence there is not given conscience, i.e., an act of certain practical judgment, which is speculative or even doubtful. But it can happen that a man by a diverse act or judgment speculatively doubts, and is practically certain, i.e., is occupied in speculative doubt, and has a certain practical conscience. But that doubt, like the speculative judgment, is not a doubt or judgment of conscience, but precedes this.

Certain conscience is that which formally and in itself, and in all the principles from which it is immediately formed, is such as to exclude every reasonable fear of the opposite.

Probable or opinionative conscience is that which from merely probable principles dictates something to be licit or illicit, with fear of the opposite part.

Doubtful conscience is the suspension of the intellect assenting to neither part of a contradiction, either because of contrary reasons equally probable, and it is called doubtful positively; or because it has no reasons pro or contra, and is called doubtful negatively. It would better be called un-knowing or ignorant. For one asking whether the sands of the sea are equal, one would better answer: « I know not, » than: « I doubt; » because if asked further why I doubt, I should have nothing to answer. Conscience doubtful in either way does not seem conscience properly and strictly so called, because it is not a definite judgment, such as conscience ought to be.