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Can Lying Ever be Right?

St. Augustine wrote the first extensive treatise on lying (De Mendacio). In it he cites the case of a holy bishop, Firmus of Thagasta, who wished to protect a man who had sought refuge with him. The bishop was so careful of the truth that, rather than lying to the imperial officers who pursued the fugitive, he told them frankly that he would not reveal the man’s location. Firmus maintained this resolve even under torture, with the result that he was eventually brought before the emperor himself. But the emperor was so impressed with the bishop’s virtue that he both praised the bishop and pardoned the fugitive.

Augustine tells this story to provide a saintly witness for his argument that lying is always morally wrong, regardless of the circumstances, and to note that God is perfectly capable of extricating from trouble those who stand fast in the truth. His treatise has been widely cited ever since, and his viewpoint was endorsed by no less saintly a scholar than Thomas Aquinas. In the monumental Summa Theologiae, Thomas states the same position: “Therefore it is not lawful to tell a lie in order to deliver another from any danger whatever. Nevertheless it is lawful to hide the truth prudently, by keeping it back, as Augustine says” (II:110:3).

But Augustine and Aquinas were both aware that even many good Christians disagreed with them. In fact, it seems likely that most people throughout history have held that not all falsehoods are morally evil. The issue has been debated intensely by moral theologians for well over 1500 years.

Can a Lie Ever Be Necessary?

Lying is held to be prohibited by the Eighth Commandment, but that commandment literally condemns only the bearing of false witness (as in a legal proceeding), so lying and other verbal sins are included by extension, through moral reasoning. Indeed, the importance of speaking the truth is thoroughly rooted in the natural law. For this reason, it has been relatively easy not only for Christians but for most others to see that, at the least, it is intrinsically immoral to speak falsely in a serious matter for an unworthy motive (such as to gain something to which one has no right, or to avoid a punishment that is justly due). Philosophers have also pointed out the violation of human integrity involved in a lie, for when we lie we speak one thing while thinking another—a practice hardly conducive to integral personal development or growth in virtue.

And yet the problem of the “necessary lie” presents itself immediately, a problem recognized and discussed down through the ages not only by Catholic saints and moral theologians, but by other Christians, non-Christians, and even those of no religion at all. The situation faced by Bishop Firmus is a classic formulation of the circumstances leading to a necessary lie. Since the mid-20th century, the same problem has been posed in terms of whether Christians hiding Jews in Nazi Germany could morally lie to those seeking to find and destroy them.

For convenience, let us put the case very precisely. Consider a man with a house guest whom a group of thugs wants to murder. The thugs come to the door. Because they don’t wish to create an outcry before they’re sure they’ve found their quarry (giving him time to escape, for example, from a neighboring house), they don’t force their way in to search. Instead, they knock on the door and simply ask whether their intended victim is within. Refusing to answer will almost certainly be interpreted as an affirmative response. So here is the dilemma: If you answer the door, and you don’t trust the thugs’ intentions, do you have to tell the truth?

Despite the strictures of both Augustine and Aquinas, the vast majority of well-formed Catholics would answer this question in the negative. Under these circumstances, they believe it is perfectly permissible to deceive the thugs at the door. As we shall see, they have saints on their side as well. But even these well-formed Catholics cannot explain why they may deceive the thugs, or at least they can’t explain it in a way which is universally accepted by sound moral theologians down through the ages, nor in a way that has (yet) been endorsed by the magisterium of the Church. In other words, most of us believe we can (and indeed should) lie under these circumstances, but we don’t know exactly why. Moreover, this has always been the case. The problem so agitated Catholic thinkers during the 17th, 18th, and 19th centuries that their less subtle Protestant brethren began to question whether Catholics believed in telling the truth.

What Is a Lie?

Note that a solution to this conundrum could come in one of two forms. It may be that: (1) The immorality of lying admits of exceptions such that there is no objective evil, or at least no subjective evil (guilt), in lying to the thugs; or (2) a very careful definition of “lying” will show that speaking falsely to the thugs is not a lie at all. Great and holy thinkers have wrestled with both possibilities, but it is perhaps more logical to take up first the question of the definition of “lying.” By carefully defining our terms, will we find that there is a distinction between speaking falsely and lying, just as there is between killing and murder? Are some falsehoods not lies? What precisely does it mean to lie?

One of the stronger philosophical traditions, endorsed by Aquinas and discussed by Augustine, posits that lying is “deliberately speaking against one’s own mind.” (Throughout this discussion, “speaking” means any sort of communication.) This was the most common definition among the scholastics, and it became a staple of theological manuals by the first part of the 20th century. As Fr. John Hardon puts it in the Modern Catholic Dictionary, “When a person tells a lie, he or she deliberately says something that is contrary to what is on that person’s mind; there is a real opposition between what one says and what one thinks” (an opposition that cannot be merely apparent, explained by ignorance or misstatement).

The first thing to notice is that this definition emphasizes the moral intentionality of lying; the truth itself is not necessarily contradicted. If a person thinks something is true and deliberately states something to the contrary, he has incurred the moral guilt of lying. While this may be so subjectively, it leaves open the possibility that such a person, believing a falsehood, could actually speak the truth by speaking against his own mind.

Because this definition is divorced from the objective truth or falsity of the statement, many philosophers and theologians have sought an alternative definition. Some have proposed that the proper definition of “lying” is “speaking a falsehood with the intention of deceiving.” In the early 20th century, the article on “Lying” in the highly-regarded Catholic Encyclopedia dismissed this definition (also traceable to Augustine) as a new and minor opinion which raised more problems than it solved. By the late 20th century, however, it was precisely this definition that made it into the Catechism of the Catholic Church (see CCC 2482).

The definition in the Catechism has the virtue of anchoring a lie in objective reality. To be properly termed a lie, a statement must fulfill two conditions: (a) It must be objectively false; (b) It must be spoken with the intention to deceive. This definition also makes it easier to dismiss falsehoods obviously told in jest (though supporters of the other definition have argued that a falsehood told in jest is not in any meaningful way contrary to one’s own mind), but it does not as easily capture the moral failure of the person who intends to lie but, because his understanding is wrong, inadvertently tells the truth. And neither definition appears to address the question of why it is moral to lie to murderous thugs.

Refined Definitions and Exceptions

Some moralists have argued that we are obliged to state the strict truth no matter what the consequences, on the principle that the end does not justify the means. Unfortunately, this makes a presumption that most thinkers would not admit: that the only reason to shy away from the truth is fear of unpleasant consequences. In the case of the murderous thugs, however, most people believe they would be complicit in a grave evil if they were to reveal the location of the intended victim, and it is worth noting that they could be charged as accomplices under most legal systems. Other moralists, as we have seen, argue that we are not strictly obliged to speak the truth, but we must not speak falsely. We may, for example, try to change the subject, keep silence, or openly refuse to answer. But in many cases this also would be likely to betray the innocent, and even very moral onlookers might well ask—somewhat contemptuously—whether this was the best we could do.

To address this critical problem more effectively, a great many moralists have tried either to tweak the definition or to suggest grounds for exceptions. For example, some proponents of the first definition have argued that a person is not really speaking against his own mind if his conscience instructs him to say something false (for example, to save an innocent person). This is internally consistent, and we must certainly follow our conscience, but it also weakens the obvious meaning of “speaking against one’s mind” and, in any case, the explanation does not provide any principle by which properly to form the conscience. Therefore, its very subjectivity renders it morally unhelpful.

Regardless of definition, many others have suggested that the immorality of lying admits of exceptions. These argue, for example, that one is not obligated to tell the truth to an enemy, or that political leaders may speak falsely for reasons of state. Such exceptions may be permitted by the principle of double effect: Just as one can morally kill to defend someone’s life, so one can morally lie for a similar reason. The deception (or killing) is a secondary effect of a legitimate action. But with killing there is more at work than double effect. It is not moral to kill anyone whose existence threatens our own lives (consider the case of abortion to save the life of the mother, or cannibalism in a life raft). Rather, the one killed must somehow have the character of an unjust aggressor. Thus we commonly define murder as the taking of an “innocent” life (that is, the right to life has not been forfeited) and we distinguish murder sharply from mere killing. If the same is true of lying, the solution is not so much a matter of exception as of definition.

The difficulty of conceptualizing the perfect definition has caused many over the centuries to insist on the existence of the necessary lie. Such a lie arises from a conflict between justice and veracity when the exercise of both virtues is demanded by the selfsame moral situation. In other words, we are obliged to tell the truth, and we are also obliged to keep secrets, but there are times when the only way to keep a secret is to lie. Both keeping secrets and speaking truthfully are included under all standard expositions of the natural law and the eighth commandment. When our obligation to protect a secret conflicts with our obligation to tell the truth, the result is a necessary lie—necessary not because it helps us to avoid some potential pain but because it is the only way to preserve justice. On this reading, a very particular exception to the rule exists when there are conflicting moral requirements. We may—indeed, we must—deceive the thugs because it is the lesser of two evils.

Mental Reservation

It seems that most moralists have believed that such a necessary lie is moral, but Catholic thinkers have often found the specific explanation troubling, because it appears to subordinate veracity to justice, when both may be considered incommensurable intrinsic goods. Such moralists, including St. Raymund of Peñafort in the 13th century and St. Alphonsus Liguori in the 18th, have tried to develop a theory of truth-telling which permits legitimate deception without formal falsehood. This theory is called mental reservation, and it has been very widely followed. For example, the Society of Jesus has been especially associated with various doctrines of mental reservation throughout most of its history.

An example may help. If you ask an attorney whether his client is guilty, he may properly answer “I don’t know,” and intelligent people in his culture will understand that this means “I have no communicable information to impart.” Hence the attorney uses a mental reservation about what he means by the words “I don’t know,” but it is a mental reservation understandable by all parties (termed a “wide” mental reservation, because its meaning is widely available). Asking a friend, family member or secretary to tell a caller you are “not in” is another example of wide mental reservation. The statement is technically false, but social convention supplies a more ambivalent meaning.

One problem with mental reservation theory is that it can make truth-telling dependent on one’s capacity for spur-of-the-moment mental sleight-of-hand (often called “strict” mental reservation because it exists strictly in the speaker’s mind alone). For example, if you’ve been playing baseball in the street (again!) and you break your neighbor’s window, the neighbor may run out and demand to know whether you did it. Under some theories of mental reservation, you can answer “no” if you are really thinking “No, I did not break it with my bat; it was the ball that broke it.” Such equivocations, whose true sense is determined only by the mind of the speaker, were condemned by the Holy See as early as 1679.

But more serious explorations of mental reservation have continued. If your house is situated at the bottom of a large hill, is it wrong to answer the thugs with a vague gesture and the words, “I saw him heading up, moving as fast as he could?” What you really mean is that you told him to run upstairs and hide in the back bedroom. Or what about a sort of double mental reservation, but all on your own side? Question: “Is John Smith in your house?” Interpretation: “Is John Smith in your house so that we may kill him?” Answer: “No.” Interpretation: “John Smith is not here to be killed.” Such examples may not be precisely strict, but it is hard to call them wide. Moreover, some forms of mental reservation appear to uphold veracity only in a technical sense while permitting the communication of a deliberate deception. Still, mental reservation was widely endorsed well into the second half of the 20th century, and many Catholics of my own age were taught it growing up.

A Promising Lead?

I referred earlier to the difficulty of conceptualizing a perfect definition of lying that might reveal a solution to our dilemma. The magisterium of the Church has not endorsed any such definition, but it recently came very close to taking a small step in that direction. Over the past hundred years there has been a growing movement among moral theologians to tweak the definition of lying as follows: “To lie is to speak or act against the truth in order to lead into error someone who has the right to know the truth.” This very sentence, in fact, is taken from the initial edition of the Catechism of the Catholic Church (CCC 2483, 1994 edition).

When the Catechism was first published in French in 1994, and translated into other languages from the French, it contained the sentence quoted above, and so there was some speculation that the Holy See had finally decided to throw at least a modicum of magisterial weight behind this solution to our dilemma. This very precise definition, with its inclusion of the right to know, enables us to handle lying and falsehood in a manner very similar to the way we handle murder and killing. Through a person’s intention to use particular knowledge for an evil end, that person would presumably forfeit his right to know. Thus it would be morally acceptable to speak a falsehood to the murderous thugs. But we would no more call this “lying” than we would call an act of self-defense “murder.”

Alas, the matter is not so easily resolved. For, as it turns out, when the official Latin text of the Catechism was released in 1997 after a process of revision, the right to know was dropped. The operative sentence now reads simply: “To lie is to speak or act against the truth in order to lead someone into error.” Of course, the Catechism is intended as a basic compendium of Catholic doctrine, assembled with due ecclesiastical care, and not as a collection of definitive infallible pronouncements permanently settling every question on every topic it covers. In other words, the change in definition does not mean the original formulation was wrong. But it does mean that the editors of the Catechism were not prepared to endorse it in an official Catholic reference work.

Our Intentions

In the end, then, the current Catechism does not directly address our problem. Still, after all the consultation which preceded the few changes that were made, the Catechismrepresents a considerable weight of ecclesiastical opinion on the side of a definition which incorporates both objective reality and human intentionality: “A lie consists in speaking a falsehood with the intention of deceiving” (a citation from Augustine), and “To lie is to speak or act against the truth in order to lead someone into error” (CCC 2482, 2483). Perhaps the very emphasis on the intention to deceive in this definition suggests another possible line of thought. For, when we speak falsely to our murderous thugs, we may at least question whether our intention is to deceive. Presumably, that intention—if it exists consciously at all—is very secondary. What we primarily intend is to prevent them from doing evil.

It would satisfy a well-formed conscience, I think, to permit the speaking of falsehood when it is the only means we can think of to prevent someone from committing an immoral act. But if so, it is hard to reach such a conclusion only by denying the intention to deceive. There must be something more than that, for we could also say that when we lied to our boss last Wednesday, our intention was not to deceive but to save our skin. Clearly this is just one more possibility for exploration, and so far all the possibilities in history have not led to a formal doctrinal development to settle the matter. It remains the case that, despite our instincts, we don’t quite know how to justify deceiving our proverbial thugs, or telling jokes that involve deception, or doing undercover police work, or engaging in military counter-intelligence activities during wartime.

Happily, the Church’s imprecision on this question does not seem to have led to a great heresy or to widespread and dangerous confusion. Perhaps the reason is simple: For most of us, the moral challenge is to find the courage to tell the truth instead of “spinning” it for petty purposes. Our most common problem is not deciding grave questions of life and death but purifying our own questionable intentions. So while lying is a fascinating subject, we are wise to remember the kinds of cases which make it so are very different from the ones we ourselves typically face. If we ask whether Augustine and Aquinas were right in condemning all falsehoods, we may well choose to answer in the negative. But if we ask whether they were right in condemning our own weak and typical lies, only one answer is possible. On these lies, every saint agrees.


Written By Jeffrey A. Mirus



  1. rosemariemorgan Reply

    Thank you for this although I’m not entirely sure it hasn’t made me even more confused than I was before.

  2. Stella francis Reply

    I understand the moral but if you write in short then it is very easier way i will very thankful.

  3. Stella francis Reply

    I m suffering from last weak high blood pressure n it’s not cure even i regular prayer also pls pray for me why this happened to me. ?my heart is so clear for everyone.

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