Reply to Objection 3: This passage refers specially to the bishops, priests, deacons and clerics of the Roman Church, on account of its dignity: and this for three reasons. First because in that Church those men ought to be promoted whose sanctity makes their evidence of more weight than that of many witnesses. Secondly, because those who have to judge other men, often have many opponents on account of their justice, wherefore those who give evidence against them should not be believed indiscriminately, unless they be very numerous. Thirdly, because the condemnation of any one of them would detract in public opinion from the dignity and authority of that Church, a result which would be more fraught with danger than if one were to tolerate a sinner in that same Church, unless he were very notorious and manifest, so that a grave scandal would arise if he were tolerated.
Whether a man's evidence can be rejected without any fault of his?
Objection 1: It would seem that a man's evidence ought not to be rejected except on account of some fault. For it a penalty on some that their evidence is inadmissible, as in the case of those who are branded with infamy. Now a penalty must not be inflicted save for a fault. Therefore it would seem that no man's evidence ought to be rejected save on account of a fault.
Objection 2: Further, "Good is to be presumed of every one, unless the contrary appear" [*Cap. Dudum, de Praesumpt.]. Now it pertains to a man's goodness that he should give true evidence. Since therefore there can be no proof of the contrary, unless there be some fault of his, it would seem that no man's evidence should be rejected save for some fault.
Objection 3: Further, no man is rendered unfit for things necessary for salvation except by some sin. But it is necessary for salvation to give true evidence, as stated above (A[1]). Therefore no man should be excluded from giving evidence save for some fault.
On the contrary, Gregory says (Regist. xiii, 44): "As to the bishop who is said to have been accused by his servants, you are to know that they should by no means have been heard": which words are embodied in the Decretals II, qu. 1, can. Imprimis.
I answer that, As stated above (A[2]), the authority of evidence is not infallible but probable; and consequently the evidence for one side is weakened by whatever strengthens the probability of the other. Now the reliability of a person's evidence is weakened, sometimes indeed on account of some fault of his, as in the case of unbelievers and persons of evil repute, as well as those who are guilty of a public crime and who are not allowed even to accuse; sometimes, without any fault on his part, and this owing either to a defect in the reason, as in the case of children, imbeciles and women, or to personal feeling, as in the case of enemies, or persons united by family or household ties, or again owing to some external condition, as in the case of poor people, slaves, and those who are under authority, concerning whom it is to be presumed that they might easily be induced to give evidence against the truth.
Thus it is manifest that a person's evidence may be rejected either with or without some fault of his.
Reply to Objection 1: If a person is disqualified from giving evidence this is done as a precaution against false evidence rather than as a punishment. Hence the argument does not prove.
Reply to Objection 2: Good is to be presumed of everyone unless the contrary appear, provided this does not threaten injury to another: because, in that case, one ought to be careful not to believe everyone readily, according to 1 Jn. 4:1 : "Believe not every spirit."
Reply to Objection 3: To give evidence is necessary for salvation, provided the witness be competent, and the order of justice observed. Hence nothing hinders certain persons being excused from giving evidence, if they be considered unfit according to law.
Whether it is always a mortal sin to give false evidence?
Objection 1: It would seem that it is not always a mortal sin to give false evidence. For a person may happen to give false evidence, through ignorance of fact. Now such ignorance excuses from mortal sin. Therefore the giving of false evidence is not always a mortal sin.
Objection 2: Further, a lie that benefits someone and hurts no man is officious, and this is not a mortal sin. Now sometimes a lie of this kind occurs in false evidence, as when a person gives false evidence in order to save a man from death, or from an unjust sentence which threatens him through other false witnesses or a perverse judge. Therefore in such cases it is not a mortal sin to give false evidence.
Objection 3: Further, a witness is required to take an oath in order that he may fear to commit a mortal sin of perjury. But this would not be necessary, if it were already a mortal sin to give false evidence. Therefore the giving of false evidence is not always mortal sin.
On the contrary, It is written ( Prov. 19:5 ): "A false witness shall not be unpunished."
I answer that, False evidence has a threefold deformity. The first is owing to perjury, since witnesses are admitted only on oath and on this count it is always a mortal sin. Secondly, owing to the violation of justice, and on this account it is a mortal sin generically, even as any kind of injustice. Hence the prohibition of false evidence by the precept of the decalogue is expressed in this form when it is said ( Ex. 20:16 ), "Thou shalt not bear false witness against thy neighbor." For one does nothing against a man by preventing him from doing someone an injury, but only by taking away his justice. Thirdly, owing to the falsehood itself, by reason of which every lie is a sin: on this account, the giving of false evidence is not always a mortal sin.
Reply to Objection 1: In giving evidence a man ought not to affirm as certain, as though he knew it, that about which he is not certain and he should confess his doubt in doubtful terms, and that which he is certain about, in terms of certainty. Owing however to the frailty of the human memory, a man sometimes thinks he is certain about something that is not true; and then if after thinking over the matter with due care he deems himself certain about that false thing, he does not sin mortally if he asserts it, because the evidence which he gives is not directly an intentionally, but accidentally contrary to what he intends.
Reply to Objection 2: An unjust judgment is not a judgment, wherefore the false evidence given in an unjust judgment, in order to prevent injustice is not a mortal sin by virtue of the judgment, but only by reason of the oath violated.
Reply to Objection 3: Men abhor chiefly those sin that are against God, as being most grievous and among them is perjury: whereas they do not abhor so much sins against their neighbor. Consequently, for the greater certitude of evidence, the witness is required to take a oath.