Summa summae S. Thomae, Tomus III

A doubt can be interpreted in the better part in two ways: one way, negatively, by not declining into the worse; the other way, positively, by declining into the better.

I say 1°: Doubts about the evil of one's neighbor must be interpreted in the better part negatively. It follows from the preceding article and from the same principle.

Proof. By this very fact that someone has an evil opinion of another without sufficient cause, he despises him and injures him, as was said; which is illicit. Now he who does not interpret a doubt about the evil of his neighbor in the better part at least negatively, but declines into the worse, has an evil opinion of his neighbor without sufficient cause, since the reasons for doubting lie on both sides, and are therefore insufficient for suspecting or opining in the worse direction. Therefore.

The same is proved by all that we have said against suspicion and rash judgment.

I say 2°: Doubts about the evil of one's neighbor are not always to be interpreted positively in the better part, but only in certain cases.

Proof. 1° because the precept of judging one's neighbor well in doubt is affirmative, like the precept of honoring or loving him, which does not bind always.

Proof. 2°. Either there are sufficient reasons for doubting, or there are not. If the first, we can remain in doubt, suspending judgment and not declining to either side; because the doubt is not rash, but reasonable. If the second, the doubt must be rejected at once, because it is rash. But that is not our case; for we are dealing with a founded and reasonable doubt.

Nevertheless — and this is the second part of the conclusion — supposing that, with the matter doubtful on both sides, some act must be elicited concerning the goodness or malice of one's neighbor, that act must be done in the better part, and consequently the doubt must be interpreted positively in the better part; and the reasons of the first conclusion prove this directly.

Likewise, if a grave temptation pressed upon one to have an evil opinion or judgment of one's neighbor, which one could not conquer except by judging positively on the good side, one would also be bound to that, for the same reason.

Wherefore it is also licit, concerning the business undertaken, or on another day at that time, with caution intact, to doubt toward the worse parts by supposing, not that things appear to be worse there, or even by judging that they could be such. For thus it is expedient that the remedy or precaution be applied more securely, because a remedy which is efficacious against a greater evil is much more efficacious against a lesser evil; nor do you injure anyone; for you do not judge, nor suspect or doubt that your neighbor is in fact vicious, but you merely suppose him to be such, or judge that he could be such, which is indeed true and not injurious to him, and from that supposition you provide for yourself and yours as if he were truly such.

We use this kind of supposition everywhere without sin. Thus a father prudently forbids his daughter the company of some young man, because she may be seduced by him. A master closes the chest more attentively and guards his money, because servants or unknown guests may be thieves. A traveler takes up arms on meeting an unknown man, because he may be a robber; he avoids meeting a deformed old woman, because she may be a witch. And so many other cases. Take care, however, always to keep in mind a right judgment about your neighbor, nor doubt, suspect, or judge beyond the sufficiency of the indications. Provide for your own likewise, so that through excessive caution you do not defame or sadden your neighbor.

[Whether public judgment is to be rendered according to the laws, and whether through usurpation it becomes perverse, which St. Thomas discusses here in art. 5 and 6¹ , will be said below, when we treat of the injustice of the judge.]