As with any U.S. election season, the 2024 presidential election is filled with endless “fact checks” and accusations of falsehoods against various politicians. Separating lies from facts is ultimately up to the voter and lying may seem unimportant these days in the grand scheme of things, but what does the Catholic Church teach about it?

Unsurprisingly, after 20 centuries, the Church has a lot to say about lying, one of the most common phenomena of the human experience. 

One of the Ten Commandments is “Thou shalt not bear false witness against thy neighbor” and the Catechism of the Catholic Church states: “Lying is to speak or act against the truth in order to lead someone into error” (No. 2483). 

“By injuring man’s relation to truth and to his neighbor, a lie offends against the fundamental relation of man and of his word to the Lord,” the catechism continues. 

The catechism notes in No. 2484 that a lie’s severity “is measured against the nature of the truth it deforms” and that one must consider “the circumstances, the intentions of the one who lies, and the harm suffered by its victims.” A lie that constitutes a venial sin “becomes mortal when it does grave injury to the virtues of justice and charity.”

Some of the Church’s most towering thinkers have similarly condemned lying. St. Thomas Aquinas said lying was “directly and formally opposed to the virtue of truth.”

St. Augustine, meanwhile, argued that “whoever shall think there is any sort of lie that is not sin, will deceive himself foully, while he deems himself honest as a deceiver of other men.” 

There seems to be little disagreement among moral authorities as to the wrongness of lying in general. But there has been some debate as to whether or not some types of falsehoods can be justified in certain circumstances, such as when telling some or all of the truth would bring about unjust harm against innocents. 

One fabled example concerns St. Athanasius, who legend has it was rowing away from his persecutors on a river. When he encountered a group of searchers who asked if he knew where Athanasius was located, he reportedly responded: “He’s not far away!” after which he was able to flee. 

Other examples involve similarly extreme circumstances, such as if a murderous villain demands to know the location of an innocent person he intends to kill. 

Patrick Lee, a professor of philosophy at Franciscan University of Steubenville in Ohio, told CNA: “My view is that St. Thomas and St. Augustine and the catechism are right, that all lying is wrong.”

He acknowledged that there are “difficulties” in that prohibition, such as the famous example of someone hiding Jewish refugees in their home and having to respond to Nazis searching for them. 

Still, “the rules are really, really clear in Scripture,” he argued. He cited Jesus’ sharp words in John 8 in which Christ points out that Satan “does not stand in the truth because there is no truth in him,” that in lying the devil “speaks according to his own nature,” and that he “is a liar and the father of lies.”

“It really does sound like you have an obligation to the truth,” Lee said. Satan, he argued, “is the source of lying — all lying.”

Nevertheless, there have been attempts among Catholic thinkers over the years to justify some forms of lying or dishonesty. The Jesuits many years ago popularized the practice of “mental reservation,” a controversial philosophical principle that critics have argued is tantamount to lying. 

Jimmy Akin, a senior apologist at Catholic Answers, told CNA that when practicing mental reservation, “one says something that is technically true but withholds or reserves part of the truth.”

(Story continues below)

“On the basis of this partial disclosure of truth, the person to whom one is speaking may draw an incorrect conclusion, but one would not have said something technically false and thus not lied,” he said. 

An example of mental reservation could be when an abusive husband demands to know where his wife is hiding. The woman’s protector might respond, “I have not seen your wife,” while thinking to himself, “...in the last 30 seconds.” 

“The concept of mental reservation has been criticized on the ground that many mental reservations involve telling a truth in a deliberately misleading way and thus involve deliberate deception, making them functionally equivalent to lying,” Akin said. 

Akin noted that in recent years some Catholic moral theologians “have been exploring other theories that seek to balance the importance of truth-telling with the seeming practical need to use deception in some circumstances.” 

“This may be in part a response to the totalitarian regimes that arose in the 20th century and the need to deceive them in order to protect human life,” he said. 

The idea of using falsehoods to save innocent victims from violent aggressors received renewed attention several years ago when Pope Francis admitted that, as a young priest in Argentina, he participated in what it could be argued were false and duplicitous actions as part of efforts to work against the dictatorship there. 

Akin wrote in 2013 that the faithful should be “cautious of drawing implications from this,” in part because “people can and do make mistakes.” Additionally, at the time, Francis “was not yet pope and did not have the responsibility and the graces of that office.”

He pointed out to CNA, however, that at one point the Catechism of the Catholic Church qualified its prohibition on lying: It previously held that “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.” The “right-to-know” proviso was removed in 1997.

“To my knowledge, the Holy See didn’t comment on the reason for the change,” Akin said, “but it presumably was to avoid adopting one, specific, recent theory of lying when others were still legitimate also.”

The older directive “seemed to support a theory in moral theology that would permit lying in cases where the person had no right to know the truth, such as in the famous example of lying to Nazis about the location of hidden Jewish individuals,” Akin said. 

Lee said lying represents a fundamental betrayal of the person to whom you are telling the falsehood.

“You’re inviting someone to trust you that what you’re saying is in your mind,” he said. “So you, in a way, betray that trust. You ask them to believe you in the sense that what you’re saying is what you think. You’re presenting a false self and blocking community with them.”

Akin, meanwhile, pointed out that “historically, the most prominent view has been the one supported by St. Thomas Aquinas.”

“He held that lying is intrinsically wrong as a perversion of the human faculty of speech, which he saw as oriented toward communicating truthful information in a way that would preclude lying,” Akin said.

“On his view, lying is never permissible, and so one could not lie to Nazis about hiding Jews in one’s attic. One would have to do something else.”

“Examples of things a non-exception-making Thomist might do include shutting the door in the Nazis’ faces without saying anything or using a mental reservation of some kind,” he said.

“The difficulty for the Thomist,” Akin pointed out, “is finding something that would be effective (if you shut the door, the Nazis may just kick it in and search the house) and that would not involve deliberate deception (as many mental reservations do).”