Whether Every Lie Is a Sin?
Objection 1: It seems that not every lie is a sin. For it is evident that the evangelists did not sin in the writing of the Gospel. Yet they seem to have told something false: since their accounts of the words of Christ and of others often differ from one another: wherefore seemingly one of them must have given an untrue account. Therefore not every lie is a sin.
Obj. 2: Further, no one is rewarded by God for sin. But the midwives of Egypt were rewarded by God for a lie, for it is stated that "God built them houses" (Ex. 1:21). Therefore a lie is not a sin.
Obj. 3: Further, the deeds of holy men are related in Sacred Writ that they may be a model of human life. But we read of certain very holy men that they lied. Thus (Gen. 12 and 20) we are told that Abraham said of his wife that she was his sister. Jacob also lied when he said that he was Esau, and yet he received a blessing (Gen. 27:27-29). Again, Judith is commended (Judith 15:10, 11) although she lied to Holofernes. Therefore not every lie is a sin.
Obj. 4: Further, one ought to choose the lesser evil in order to avoid the greater: even so a physician cuts off a limb, lest the whole body perish. Yet less harm is done by raising a false opinion in a person's mind, than by someone slaying or being slain. Therefore a man may lawfully lie, to save another from committing murder, or another from being killed.
Obj. 5: Further, it is a lie not to fulfill what one has promised.
Yet one is not bound to keep all one's promises: for Isidore says
(Synonym. ii): "Break your faith when you have promised ill."
Therefore not every lie is a sin.
Obj. 6: Further, apparently a lie is a sin because thereby we deceive our neighbor: wherefore Augustine says (Lib. De Mend. xxi): "Whoever thinks that there is any kind of lie that is not a sin deceives himself shamefully, since he deems himself an honest man when he deceives others." Yet not every lie is a cause of deception, since no one is deceived by a jocose lie; seeing that lies of this kind are told, not with the intention of being believed, but merely for the sake of giving pleasure. Hence again we find hyperbolical expressions in Holy Writ. Therefore not every lie is a sin.
On the contrary, It is written (Ecclus. 7:14): "Be not willing to make any manner of lie."
I answer that, An action that is naturally evil in respect of its genus can by no means be good and lawful, since in order for an action to be good it must be right in every respect: because good results from a complete cause, while evil results from any single defect, as Dionysius asserts (Div. Nom. iv). Now a lie is evil in respect of its genus, since it is an action bearing on undue matter. For as words are naturally signs of intellectual acts, it is unnatural and undue for anyone to signify by words something that is not in his mind. Hence the Philosopher says (Ethic. iv, 7) that "lying is in itself evil and to be shunned, while truthfulness is good and worthy of praise." Therefore every lie is a sin, as also Augustine declares (Contra Mend. i).
Reply Obj. 1: It is unlawful to hold that any false assertion is contained either in the Gospel or in any canonical Scripture, or that the writers thereof have told untruths, because faith would be deprived of its certitude which is based on the authority of Holy Writ. That the words of certain people are variously reported in the Gospel and other sacred writings does not constitute a lie. Hence Augustine says (De Consens. Evang. ii): "He that has the wit to understand that in order to know the truth it is necessary to get at the sense, will conclude that he must not be the least troubled, no matter by what words that sense is expressed." Hence it is evident, as he adds (De Consens. Evang. ii), that "we must not judge that someone is lying, if several persons fail to describe in the same way and in the same words a thing which they remember to have seen or heard."