Summa summae S. Thomae, Tomus II

You will ask 1° how great, in the less safe opinion, the excess of probability must be, that it may be lawful to follow it.

I answer. It is not required that it be the most probable, nor does any light excess in probability suffice; but a notable and morally grave one is required.

The reason of the first part is : 1° Because he who follows the more probable acts prudently, as was proved. Therefore this suffices, nor is the most probable required. 2° Because if the most probable were required, it would be so, according to its patrons, in order that no probable danger of sin remain. But then it would cease to be most probable and would become morally certain, and thus it would never be lawful to follow the most probable among probable opinions; which is rejected. Therefore. 3° Nothing is opposed against a more probable opinion which cannot be opposed against the most probable, as appears from what has been said. But this notwithstanding, the most probable suffices. Therefore also the more probable. 3° The contrary opinion would furnish occasion for continuous scruples and anxieties, since it could scarcely be discerned when an opinion would be the most probable, unless perhaps by most probable they understand gravely more probable.

The reason of the second part is, because such and so great must be the excess that, morally speaking, it shake off doubt and move a grave and prudent man to assent to it rather than to the other. But, morally speaking, any thin and light excess does not suffice for this; little indeed is reckoned as nothing in moral matters. Therefore.

You will ask 2° how a confessor, or a learned man consulted about the liceity or illicitness of some action, v. g., whether a triple contract be licit, ought to answer the consulter.

I answer. He cannot answer according to the less probable opinion, whether less safe or safer; because either he would say licit what he himself judges more probably illicit, or he would say illicit what he himself judges more probably licit; and thus he would lead the consulter into doing what he himself, being consulted, judges evil, or into abstaining from what he judges good, and would therefore deceive the consulter on either side, either too much relaxing or too much straitening his conscience.

He must therefore answer according to the more probable opinion which he holds, yet not always simply and absolutely. For if the opposite opinion also be truly probable and be upheld by many learned men as more probable, and a loss to a third party be at stake, suppose because restitution to be made or a contract to be entered upon is in question; he ought to answer that he himself feels more probably thus for such and such reasons, yet that there are not lacking learned and grave men who hold the opposite, whom he can approach, and that he choose before God what will be more probable to him. The reason is, because if he answered simply and absolutely according to the opinion more probable to himself, he would expose the consulter to danger, namely of restoring what he ought not restore, or of not restoring what he ought restore, or of entering a contract harmful to another, or of abstaining from a contract profitable to himself.

You will ask 3° whether a confessor can and ought to absolve a penitent resisting his opinion.

I answer. 1° If the opinion of the penitent be certainly less probable, and he acknowledge it as such, and wish to follow it, the confessor ought to deny him absolution, as indisposed, even though he say he is a probabilist¹. This is clear from what was said in art. 1.

2° If the opinion of the penitent be singular, supported by no solid reason and scarcely championed by anyone of weight, however much the penitent from pertinacy esteem it more probable, the confessor ought to instruct him concerning the improbability of his opinion, and if he will not acquiesce, to dismiss him unabsolved; because he who irrationally and out of pertinacy adheres to an improbable opinion is not sufficiently disposed.

3° Finally, if the opinion of the penitent, which he believes more probable, be truly solidly probable and championed by many grave and learned men as more probable, a distinction must be made. Either by following it the validity of the sacrament is imperiled, as if the penitent judge it more probable that merely timid attrition suffices, and approach otherwise undisposed; unless he abandon it, he ought not be absolved, because by his own judgment he exposes the sacrament to nullity². Or by following it the value of the sacrament is not imperiled, suppose if he judge it more probable that he is not bound to restitution in such a case, or to abstain from such a contract; even if he will not acquiesce with the confessor, and be otherwise disposed, he ought to be left in his opinion and absolved; because 1° in an equal cause the confessor ought not flatter himself, nor believe that he holds the key of knowledge, as if he alone knew all things and alone saw, while others who hold the opposite are blind and in a state of damnation; 2° because the penitent, after he has declared his sins and is otherwise disposed, has a right to absolution, which the confessor cannot deny him without injury, nor judge him indisposed because he adheres to an opinion well founded as more probable for himself, since acting according to it he does not sin. Therefore.

You will ask 4° whether it is lawful for everyone to follow the opinion which he esteems at first sight more probable.

I answer. No one can lawfully follow except that opinion which, after sufficient diligence applied, proportioned to the quality of the thing, the condition of the person and the opportunity of time, he sincerely judges before God more probable; because otherwise he would act imprudently and rashly, voluntarily exposing himself to the danger of acting against the law.

But what diligence is to be esteemed sufficient? Although no certain general rule can be given, nevertheless according as it more commonly happens I propose the following:

The unlettered may esteem as more probable and safely follow the opinion or counsel of their pastor or confessor who is held a prudent and learned man, or of another man equally prudent and learned; because they have nothing better they can do. But if they consult two of equal weight contradicting each other, let them choose the safer.

The half-learned should consult those more learned, suspect neither of excessive rigor nor of excessive laxity, or should peruse books in which, when they find an opinion unanimously asserted by authors, and the opposite passed over in silence or rejected with one mouth, they may follow it as more probable. If they read an author confessing that the common opinion is opposed to his own less safe one, let them follow the common; because those half-learned cannot of themselves weigh the force of reasons, and can scarcely follow any other rule than that of authority. If the grave author whom they read says two contradictory opinions are equally probable, let them follow the safer; if the less safe be more probable, they may follow it.

Finally, learned men should hold as more probable, and persuade others as such, that opinion which, passions and prejudices set aside, but the moments of the reasons on this side and that maturely weighed, and the gravity and weight of authors pro and con attended to, they sincerely judge such before God.

PRINCIPLES

1° Among the moral virtues prudence holds the principal place; for it is at once the head and, as St. Thomas says, the « complement »³ of all the others, directing them that they be exercised within the limits of good and right. Whence, unless man acts prudently, he does not act rightly. Moreover, as long as he is anguished in a practical doubt concerning the honesty of an action to be posited here and now, he does not act licitly unless the doubt be shaken off, that is, unless he determine himself under the guidance of prudence, by which, as the same Angelic Doctor says, « according to its essence it is an intellectual virtue, but according to its matter it accords with the moral virtues; for it is right reason of things to be done »⁴. For « it pertains to prudence not only the consideration of reason, but also the application to work, which is the end of practical reason »⁵. Therefore the whole question of probability is reduced to one point, namely whether, when the law is doubtful, that is, only probably existing, the agent acting prudently can embrace and follow the opinion favoring liberty.

2° Moreover no one acts prudently unless he be morally certain of the honesty of his action; for the Apostle says, Rom., XIV, 23 : All that is not of faith, that is, of firm and founded persuasion of the legitimacy of the action, is sin. Here there is not treated of objective certitude, which cannot be obtained when the action is only probably commanded or forbidden, because then the morality of the very action is doubtful. There is required therefore subjective certitude. And this certitude cannot be metaphysical in practical things, in which are applied only remote conclusions of principles speculative and known through themselves.

There suffices therefore moral certitude, to which alone belongs the order in which it is required. There must be asked therefore whether the agent can be morally certain of the honesty of his action, omitting the doubtful or probable law and following the opinion favoring liberty.

3° From thence it must be concluded that probability alone does not of itself confer the right of acting against a doubtful law. For if the honesty of the action is only probable, it remains doubtful, and since the action is to be posited here and now, the agent is constituted in practical doubt, in which it is not lawful to act unless the safer part be preferred, because he who does not act from faith has no moral certitude of the honesty of his action, and knowingly and voluntarily commits himself to the danger of sinning, and by that very fact sins formally, even though the matter of sin be not actually present. For he is not led by the virtue of prudence, which, as we said, is « right reason of things to be done. » It is necessary therefore that, in this case, conscience be formed and made certain from some principle taken outside probability itself, by which it is demonstrated that it is practically licit to act against a doubtful law.

From this it follows that that principle invoked by certain probabilists does not suffice : « He who acts probably acts prudently. » For if it be taken nakedly and in itself, it is deservedly attacked by the adversaries, because from such probability there cannot of itself follow anything except the probability of the honesty of the action, which cannot render conscience morally certain. But that it be admitted, it must be understood in this sense, that one acts probably legitimately when the probability affects only the obligation of the doubtful law, and conscience is rendered certain elsewhere concerning the honesty of the action.

4° From these things it is clear that the principles by which conscience is formed in practice must be sought outside the practical case; for if they could be drawn directly from the very question, the doubt would vanish and certitude occupy the place of probability. These principles, now perspicuous in themselves, or demonstrated and admitted, project into the doubtful case their own proper light, which is reflected from thence toward the intellect of the agent, so that the moral obscurity called a practical doubt is wholly dissipated, although the thing itself objectively do not yet become clear.