The truth, the whole truth, about white lies

George Washington is widely quoted as saying, "I cannot tell a lie". Although he never actually uttered these words, if he had, the statement would almost certainly be untrue. We all tell lies. Some people feel that they never lie, but I doubt that they are correct. Not telling the full truth, which surely everyone does at times, could be said to qualify as a lie. Although lying is justifiable in certain circumstances, and white lies are relatively harmless, all other forms of lie are at least counterproductive and many are harmful, destroying the trust on which civilised relations between people is based.

Children start to tell lies around the age of four or five, when they become aware of the power of language. Lying at this stage is not malicious but is used to determine what we can manipulate in our environment. Children later lie to get out of trouble or to get something they want.

White lies are often told to spare people's feelings. For example, you meet a friend just out of hospital and he is looking poorly. He asks you how he looks, and you reply "You look grand" in order to keep his spirits up.

Although such lies are generally considered to be relatively harmless, Sam Harris, neuroscientist and science writer, doesn't agree. In his book Lying (2013), he argues that even a white lie "denies our friends access to reality – and their resulting ignorance often harms them in ways we did not anticipate. Our friends may act on our falsehoods, or fail to solve problems that could have been solved on the basis of good information."

Harris advises that in situations such as the one I describe above, we should strive to tell the truth with tact.

There are extreme situations where lying is clearly the right thing to do. Say you live under a tyrannical dictatorship and your son, a political opponent of the president, is on the run. He is hiding in your attic when the president’s soldiers arrive and ask if your son is at home. You know if they capture your son they will kill him, so you lie to protect him.

Lying to feel better

People commonly lie to make themselves feel better (Michael Shermer, Scientific American, 2014). Behavioural economist Dan Ariely describes an experiment in which subjects solve as many number problems as possible in a limited time, getting paid for each correct answer (The Honest Truth about Dishonesty, 2012).

The average score was four out of 20 when the subjects reported their results to the experimenter in the room. However, in a variation of the experiment where the subjects counted their correct answers and reported this number to the experimenter in another room, the average score was six correct out of 20, an increase of 10 per cent. This effect held when the prize for a correct answer increased from 25 cent to 50 cent, to $1, to $2 and to $5. However, at $10 the amount of lying decreased slightly.

Ariely concludes that small lies are a form of self-deception that allows us to boost our image while retaining the perception we are honest. Big lies do not work like this.

The psychologist Shaul Shalvi and others have shown that people are more likely to lie when they can justify the deception to themselves (Psychological Science, 2012). Subjects were asked to roll a dice three times and report the number that came up in the first roll. The higher the number the more money they were paid. The experimenter couldn't see the dice. The subjects tended to report the highest number of the three rolls, feeling justified in doing so because that number had actually come up.

When the subjects were divided into two groups, one group having to report the highest roll number within 20 seconds and the second group given unlimited time to report, those pressed for time lied more often than those who had time to think.

And now for a puzzle involving lies. You approach a T-junction. One road leads to the King's castle. You want to go to the castle but don't know the direction. Two men who know the way stand at the junction. One man always lies, the other always tells the truth. You can determine which road leads to the king from the answer you get by asking one man one question. What is the question? (Answer below)

William Reville is an Emeritus Professor of Biochemistry at UCC. understandingscience.ucc.ie

Answer: Ask one man how his companion would answer when asked the direction to the king. The correct direction is the opposite to the answer you receive.