Of the Vices Opposed to Truth, and First of Lying

I answer that, A moral act takes its species from two things, its object, and its end: for the end is the object of the will, which is the first mover in moral acts. And the power moved by the will has its own object, which is the proximate object of the voluntary act, and stands in relation to the will's act towards the end, as material to formal, as stated above (I-II, Q. 18, AA. 6, 7).

Now it has been said above (Q. 109, A. 1, ad 3) that the virtue of truth—and consequently the opposite vices—regards a manifestation made by certain signs: and this manifestation or statement is an act of reason comparing sign with the thing signified; because every representation consists in comparison, which is the proper act of the reason. Wherefore though dumb animals manifest something, yet they do not intend to manifest anything: but they do something by natural instinct, and a manifestation is the result. But when this manifestation or statement is a moral act, it must needs be voluntary, and dependent on the intention of the will. Now the proper object of a manifestation or statement is the true or the false. And the intention of a bad will may bear on two things: one of which is that a falsehood may be told; while the other is the proper effect of a false statement, namely, that someone may be deceived.

Accordingly if these three things concur, namely, falsehood of what is said, the will to tell a falsehood, and finally the intention to deceive, then there is falsehood—materially, since what is said is false, formally, on account of the will to tell an untruth, and effectively, on account of the will to impart a falsehood.

However, the essential notion of a lie is taken from formal falsehood, from the fact namely, that a person intends to say what is false; wherefore also the word mendacium (lie) is derived from its being in opposition to the mind. Consequently if one says what is false, thinking it to be true, it is false materially, but not formally, because the falseness is beside the intention of the speaker so that it is not a perfect lie, since what is beside the speaker's intention is accidental for which reason it cannot be a specific difference. If, on the other hand, one utters falsehood formally, through having the will to deceive, even if what one says be true, yet inasmuch as this is a voluntary and moral act, it contains falseness essentially and truth accidentally, and attains the specific nature of a lie.

That a person intends to cause another to have a false opinion, by deceiving him, does not belong to the species of lying, but to perfection thereof, even as in the physical order, a thing acquires its species if it has its form, even though the form's effect be lacking; for instance a heavy body which is held up aloft by force, lest it come down in accordance with the exigency of its form. Therefore it is evident that lying is directly an formally opposed to the virtue of truth.

I answer that, Lies may be divided in three ways. First, with respect to their nature as lies: and this is the proper and essential division of lying. In this way, according to the Philosopher (Ethic. iv, 7), lies are of two kinds, namely, the lie which goes beyond the truth, and this belongs to "boasting," and the lie which stops short of the truth, and this belongs to "irony." This division is an essential division of lying itself, because lying as such is opposed to truth, as stated in the preceding Article: and truth is a kind of equality, to which more and less are in essential opposition.

Secondly, lies may be divided with respect to their nature as sins, and with regard to those things that aggravate or diminish the sin of lying, on the part of the end intended. Now the sin of lying is aggravated, if by lying a person intends to injure another, and this is called a "mischievous" lie, while the sin of lying is diminished if it be directed to some good—either of pleasure and then it is a "jocose" lie, or of usefulness, and then we have the "officious" lie, whereby it is intended to help another person, or to save him from being injured. In this way lies are divided into the three kinds aforesaid.

Thirdly, lies are divided in a more general way, with respect to their relation to some end, whether or not this increase or diminish their gravity: and in this way the division comprises eight kinds, as stated in the Second Objection. Here the first three kinds are contained under "mischievous" lies, which are either against God, and then we have the lie "in religious doctrine," or against man, and this either with the sole intention of injuring him, and then it is the second kind of lie, which "profits no one, and injures someone"; or with the intention of injuring one and at the same time profiting another, and this is the third kind of lie, "which profits one, and injures another." Of these the first is the most grievous, because sins against God are always more grievous, as stated above (I-II, Q. 73, A. 3): and the second is more grievous than the third, since the latter's gravity is diminished by the intention of profiting another.

After these three, which aggravate the sin of lying, we have a fourth, which has its own measure of gravity without addition or diminution; and this is the lie which is told "out of mere lust of lying and deceiving." This proceeds from a habit, wherefore the Philosopher says (Ethic. iv, 7) that "the liar, when he lies from habit, delights in lying."

The four kinds that follow lessen the gravity of the sin of lying. For the fifth kind is the jocose lie, which is told "with a desire to please": and the remaining three are comprised under the officious lie, wherein something useful to another person is intended. This usefulness regards either external things, and then we have the sixth kind of lie, which "profits someone in saving his money"; or his body, and this is the seventh kind, which "saves a man from death"; or the morality of his virtue, and this is the eighth kind, which "saves him from unlawful defilement of his body."

Now it is evident that the greater the good intended, the more is the sin of lying diminished in gravity. Wherefore a careful consideration of the matter will show that these various kinds of lies are enumerated in their order of gravity: since the useful good is better than the pleasurable good, and life of the body than money, and virtue than the life of the body.

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).

I answer that, A mortal sin is, properly speaking, one that is contrary to charity whereby the soul lives in union with God, as stated above (Q. 24, A. 12; Q. 35, A. 3). Now a lie may be contrary to charity in three ways: first, in itself; secondly, in respect of the evil intended; thirdly, accidentally.

A lie may be in itself contrary to charity by reason of its false signification. For if this be about divine things, it is contrary to the charity of God, whose truth one hides or corrupts by such a lie; so that a lie of this kind is opposed not only to the virtue of charity, but also to the virtues of faith and religion: wherefore it is a most grievous and a mortal sin. If, however, the false signification be about something the knowledge of which affects a man's good, for instance if it pertain to the perfection of science or to moral conduct, a lie of this description inflicts an injury on one's neighbor, since it causes him to have a false opinion, wherefore it is contrary to charity, as regards the love of our neighbor, and consequently is a mortal sin. On the other hand, if the false opinion engendered by the lie be about some matter the knowledge of which is of no consequence, then the lie in question does no harm to one's neighbor; for instance, if a person be deceived as to some contingent particulars that do not concern him. Wherefore a lie of this kind, considered in itself, is not a mortal sin.

As regards the end in view, a lie may be contrary to charity, through being told with the purpose of injuring God, and this is always a mortal sin, for it is opposed to religion; or in order to injure one's neighbor, in his person, his possessions or his good name, and this also is a mortal sin, since it is a mortal sin to injure one's neighbor, and one sins mortally if one has merely the intention of committing a mortal sin. But if the end intended be not contrary to charity, neither will the lie, considered under this aspect, be a mortal sin, as in the case of a jocose lie, where some little pleasure is intended, or in an officious lie, where the good also of one's neighbor is intended. Accidentally a lie may be contrary to charity by reason of scandal or any other injury resulting therefrom: and thus again it will be a mortal sin, for instance if a man were not deterred through scandal from lying publicly.