Objection 1. It would seem that the precept of fraternal correction does not demand that a private admonition should precede denunciation. For, in works of charity, we should above all follow the example of God, according to Ephesians 5:1-2: "Be ye followers of God, as most dear children, and walk in love." Now God sometimes punishes a man for a sin, without previously warning him in secret. Therefore it seems that there is no need for a private admonition to precede denunciation.
Objection 2. Further, according to Augustine (De Mendacio xv), we learn from the deeds of holy men how we ought to understand the commandments of Holy Writ. Now among the deeds of holy men we find that a hidden sin is publicly denounced, without any previous admonition in private. Thus we read (Genesis 37:2) that "Joseph accused his brethren to his father of a most wicked crime": and (Acts 5:4-9) that Peter publicly denounced Ananias and Saphira who had secretly "by fraud kept back the price of the land," without beforehand admonishing them in private: nor do we read that Our Lord admonished Judas in secret before denouncing him. Therefore the precept does not require that secret admonition should precede public denunciation.
Objection 3. Further, it is a graver matter to accuse than to denounce. Now one may go to the length of accusing a person publicly, without previously admonishing him in secret: for it is decided in the Decretal (Cap. Qualiter, xiv, De Accusationibus) that "nothing else need precede accusation except inscription." [The accuser was bound by Roman Law to endorse (se inscribere) the writ of accusation. The effect of this endorsement or inscription was that the accuser bound himself, if he failed to prove the accusation, to suffer the same punishment as the accused would have to suffer if proved guilty.] Therefore it seems that the precept does not require that a secret admonition should precede public denunciation.
Objection 4. Further, it does not seem probable that the customs observed by religious in general are contrary to the precepts of Christ. Now it is customary among religious orders to proclaim this or that one for a fault, without any previous secret admonition. Therefore it seems that this admonition is not required by the precept.
Objection 5. Further, religious are bound to obey their prelates. Now a prelate sometimes commands either all in general, or someone in particular, to tell him if they know of anything that requires correction. Therefore it would seem that they are bound to tell them this, even before any secret admonition. Therefore the precept does not require secret admonition before public denunciation.
On the contrary, Augustine says (De Verb. Dom. xvi, 4) on the words, "Rebuke him between thee and him alone" (Matthew 18:15): "Aiming at his amendment, while avoiding his disgrace: since perhaps from shame he might begin to defend his sin; and him whom you thought to make a better man, you make worse." Now we are bound by the precept of charity to beware lest our brother become worse. Therefore the order of fraternal correction comes under the precept.
I answer that, With regard to the public denunciation of sins it is necessary to make a distinction: because sins may be either public or secret. On the case of public sins, a remedy is required not only for the sinner, that he may become better, but also for others, who know of his sin, lest they be scandalized. Wherefore such like sins should be denounced in public, according to the saying of the Apostle (1 Timothy 5:20): "Them that sin reprove before all, that the rest also may have fear," which is to be understood as referring to public sins, as Augustine states (De Verb. Dom. xvi, 7).
On the other hand, in the case of secret sins, the words of Our Lord seem to apply (Matthew 18:15): "If thy brother shall offend against thee," etc. For if he offend thee publicly in the presence of others, he no longer sins against thee alone, but also against others whom he 'disturbs. Since, however, a man's neighbor may take offense even at his secret sins, it seems that we must make yet a further distinction. For certain secret sins are hurtful to our neighbor either in his body or in his soul, as, for instance, when a man plots secretly to betray his country to its enemies, or when a heretic secretly turns other men away from the faith. And since he that sins thus in secret, sins not only against you in particular, but also against others, it is necessary to take steps to denounce him at once, in order to prevent him doing such harm, unless by chance you were firmly persuaded that this evil result would be prevented by admonishing him secretly. On the other hand there are other sins which injure none but the sinner, and the person sinned against, either because he alone is hurt by the sinner, or at least because he alone knows about his sin, and then our one purpose should be to succor our sinning brother: and just as the physician of the body restores the sick man to health, if possible, without cutting off a limb, but, if this be unavoidable, cuts off a limb which is least indispensable, in order to preserve the life of the whole body, so too he who desires his brother's amendment should, if possible, so amend him as regards his conscience, that he keep his good name.
For a good name is useful, first of all to the sinner himself, not only in temporal matters wherein a man suffers many losses, if he lose his good name, but also in spiritual matters, because many are restrained from sinning, through fear of dishonor, so that when a man finds his honor lost, he puts no curb on his sinning. Hence Jerome says on Matthew 18:15: "If he sin against thee, thou shouldst rebuke him in private, lest he persist in his sin if he should once become shameless or unabashed." Secondly, we ought to safeguard our sinning brother's good name, both because the dishonor of one leads to the dishonor of others, according to the saying of Augustine (Ep. ad pleb. Hipponens. lxxviii): "When a few of those who bear a name for holiness are reported falsely or proved in truth to have done anything wrong, people will seek by busily repeating it to make it believed of all": and also because when one man's sin is made public others are incited to sin likewise.
Since, however, one's conscience should be preferred to a good name, Our Lord wished that we should publicly denounce our brother and so deliver his conscience from sin, even though he should forfeit his good name. Therefore it is evident that the precept requires a secret admonition to precede public denunciation.
Reply to Objection 1. Whatever is hidden, is known to God, wherefore hidden sins are to the judgment of God, just what public sins are to the judgment of man. Nevertheless God does rebuke sinners sometimes by secretly admonishing them, so to speak, with an inward inspiration, either while they wake or while they sleep, according to Job 33:15-17: "By a dream in a vision by night, when deep sleep falleth upon men... then He openeth the ears of men, and teaching instructeth them in what they are to learn, that He may withdraw a man from the things he is doing."
Reply to Objection 2. Our Lord as God knew the sin of Judas as though it were public, wherefore He could have made it known at once. Yet He did not, but warned Judas of his sin in words that were obscure. The sin of Ananias and Saphira was denounced by Peter acting as God's executor, by Whose revelation he knew of their sin. With regard to Joseph it is probable that he warned his brethren, though Scripture does not say so. Or we may say that the sin was public with regard to his brethren, wherefore it is stated in the plural that he accused "his brethren."
Reply to Objection 3. When there is danger to a great number of people, those words of Our Lord do not apply, because then thy brother does not sin against thee alone.
Reply to Objection 4. Proclamations made in the chapter of religious are about little faults which do not affect a man's good name, wherefore they are reminders of forgotten faults rather than accusations or denunciations. If, however, they should be of such a nature as to injure our brother's good name, it would be contrary to Our Lord's precept, to denounce a brother's fault in this manner.
Reply to Objection 5. A prelate is not to be obeyed contrary to a Divine precept, according to Acts 5:29: "We ought to obey God rather then men." Therefore when a prelate commands anyone to tell him anything that he knows to need correction, the command rightly understood supports the safeguarding of the order of fraternal correction, whether the command be addressed to all in general, or to some particular individual. If, on the other hand, a prelate were to issue a command in express opposition to this order instituted by Our Lord, both would sin, the one commanding, and the one obeying him, as disobeying Our Lord's command. Consequently he ought not to be obeyed, because a prelate is not the judge of secret things, but God alone is, wherefore he has no power to command anything in respect of hidden matters, except in so far as they are made known through certain signs, as by ill-repute or suspicion; in which cases a prelate can command just as a judge, whether secular or ecclesiastical, can bind a man under oath to tell the truth.
Source: Summa Theologica (New Advent)