Is every lie a sin? (ST II-II, q. 110, a. 3)

Summa article explained, no. 2. A paraphrase and reading guide, not a translation.

Why this article

It is the article people reach for when they ask the hard case: may I lie to save someone? It is also a good example of how Aquinas lets the objections carry real weight, including objections drawn from Scripture itself.

The objections

Aquinas gives six. They are worth reading in full; here is what each one presses.

1. The evangelists. The Gospels report Christ's words differently. If one account is inexact, a writer of Scripture seems to have said something false, so not every lie is a sin.
2. The midwives. The Egyptian midwives lied to Pharaoh, and "God built them houses" (Exodus 1:21). God does not reward sin.
3. The patriarchs and Judith. Abraham called Sarah his sister, Jacob said he was Esau and was blessed, and Judith is praised though she deceived Holofernes. Scripture tells holy lives as models.
4. The lesser evil. A physician cuts off a limb to save the body. Raising a false opinion in someone's mind is less harm than a killing, so it seems lawful to lie to prevent a murder or save a life.
5. Broken promises. Failing to keep a promise looks like a lie, yet not every promise binds.
6. Jokes. Nobody is deceived by a jocose lie, and Scripture itself uses hyperbole.

Sed contra

Sirach 7:14: "Be not willing to make any manner of lie."

Respondeo

The argument turns on what speech is for. An act that is evil in its kind can never be made good, because a good act must be right in every respect, while one defect is enough to make it evil (Aquinas cites Dionysius, On the Divine Names iv). Words are naturally signs of what is in the mind. To signify by words something that is not in your mind is to use the sign against its nature. So a lie is evil in its kind, not because of its consequences. Aquinas adds Aristotle (Ethics iv, 7): lying is in itself bad and to be shunned, truthfulness good and worthy of praise. Therefore every lie is a sin, as Augustine also says (Contra Mendacium i).

Lies do differ in gravity. In the previous article (a. 2) Aquinas sorts them by the end intended into mischievous, jocose and officious (helpful) lies, and the end can aggravate or lessen the sin. In the next (a. 4) he asks which are mortal. They differ in how grave they are, not in whether they are permitted.

The replies that do the work

• To the evangelists (reply 1). Reporting the same sense in different words is not a lie. Aquinas quotes Augustine: what matters is getting at the sense, whatever words express it.
• To the midwives (reply 2). They were rewarded not for the lie but for their fear of God and their good will, which led them to it. The lie itself was not meritorious.
• To the patriarchs and Judith (reply 3). Abraham hid the truth without lying: Sarah was his half-sister. Jacob spoke in a prophetic sense. Judith is praised for her desire to save her people, not for lying.
• To the lesser evil (reply 4). A lie is wrong not only because it harms a neighbour but because it is disordered in itself, and you may not use a disordered act to ward off harm from another, just as you may not steal to give alms. So it is not lawful to lie to deliver someone from any danger whatever. But it is lawful to hide the truth prudently, by keeping it back (Augustine, Contra Mendacium x).
• To promises (reply 5). You do not lie if you meant what you promised. Changing course can be excused if the promise was of something unlawful or if circumstances changed.
• To jokes (reply 6). A jocose lie is still, by its kind, apt to deceive, even if the speaker does not intend it. Figurative speech in Scripture is different: it states what its hearers understand it to mean.

The distinction is between asserting what you do not believe and not disclosing what you know. The first is a lie. The second can be prudence. Everything in the hard cases turns on it.

What this article does not settle

Whether a given evasion counts as "keeping back the truth" or as a lie in other words is a question of the particular case. Later moralists argued it at length, and the Catechism states the Church's teaching on offences against truth and respect for truth (CCC 2482 to 2492). A reading guide is not the place to decide a case of conscience.

How to work this article in Aquinian Studio

Put the hard case in disputation form: "Whether it is lawful to deceive a murderer at the door?" Aquinian distinguishes the terms (assert, deceive, conceal), orders the authorities, states the strongest objection, and runs a second pass that is allowed to wound the first. It reasons with authority. It does not become authority, and it is not a confessor. aquinian.com. New accounts start with 150 free credits, no card.

FAQ

Does Aquinas say every lie is a sin? Yes. In Summa II-II, q. 110, a. 3 he argues a lie is evil in its kind because it uses speech against its purpose, though lies differ in gravity.

What does Aquinas say about lying to save a life? That it is not lawful to lie to deliver someone from danger, but it is lawful to hide the truth prudently by keeping it back.

Why were the midwives in Exodus rewarded if lying is a sin? Aquinas says they were rewarded for their fear of God and their good will, not for the lie.