The morality of lying

Philosophical opinion is divided as to whether lying is morally wrong. Plato claimed in the Republic that rulers of a just society must promulgate “noble” lies to promote social harmony among the masses, but he also condemned the Sophists’ cavalier attitude toward truth. He apparently thought that the moral valence of lying depends upon the context in which the lie is told.

In contrast, St. Augustine—whose De mendacio, in the Reconsiderations, was the first systematic discussion of lying—argued that lying is always impermissible, although he granted as sometimes allowable that one may avoid telling the truth, a view that was later endorsed by Thomas Aquinas (c. 1224/25–1274 ce) in the Summa theologiae.

Centuries later, Hugo Grotius (1583–1645) argued that the notion of moral wrongness is built into the notion of lying. For Grotius, a harmless falsehood is by definition not a lie, so saying that lying is immoral is tautological.

Immanuel Kant (1724–1804) proposed that there are no conceivable circumstances in which lying is morally acceptable. He argued that morality is rooted in our capacity to make free, rational choices and that lying is, in effect, an assault on morality because it aims to undermine this capacity. Kant also affirmed that the moral law demands that we treat others as ends-in-themselves, whereas lying involves treating others merely as means. The Kantian perspective contrasts sharply with that of consequentialists, who hold that the moral value of an act lies entirely in the degree to which it maximizes some nonmoral good.

According to John Stuart Mill (1806–73), an act is morally obligatory only if it creates the greatest happiness for the greatest number of people, relative to its alternatives. Because there are circumstances in which lying serves the general good more effectively than truth telling does, we sometimes have a moral obligation to behave dishonestly.

The psychology of lying

Although lying was discussed by some developmental psychologists such as Jean Piaget (1896–1980) early in the 20th century, psychologists did not carry that work forward until the century’s closing decades. Psychologists have mainly been concerned with developmental aspects of lying, the frequency with which people lie, motives for lying, and methods for detecting when a person is lying.

The capacity to lie is an important developmental acquisition. Children are unable to lie until they develop a theory of mind—that is, until they are able to understand that other people are centres of experience and initiative. Once children develop a theory of mind and become able to grasp the fact that people perceive the world from a variety of perspectives, they begin to realize that people can conceal information from one another. The theory of mind is usually in place by the age of three, although there is evidence that children begin to behave deceptively as early as six months of age.

Psychologists have found that most people lie far more frequently than they are prepared to admit, even to themselves. The most commonly mentioned figure for the incidence of lying comes from a 2002 study conducted by American psychologist Robert S. Feldman that suggests that people lie on average two to three times for every 10 minutes of conversation time. Psychologists have identified a number of motives for lying, chief among which are the need to preserve self-esteem, the wish to avoid conflict, and the desire to manipulate others to behave in ways that are in one’s self-interest.

Experimental studies have revealed the disquieting fact that most people are extremely bad at detecting lies. Most are able to correctly identify lies just over 50 percent of the time, while seasoned law-enforcement officers and judges fare only marginally better. However, a small proportion of the population (less than 1 percent of the people studied) are naturally talented at detecting lies. American psychologist Paul Ekman showed that people who are good at detecting mendacity pay careful attention to nonverbal cues. Fleeting alterations in the speaker’s facial expression (“microexpressions”) are especially revealing. Ekman also showed that subjects can be taught to recognize and interpret microexpressions, a skill that results in dramatic improvement to their ability to discern lies.