Whether to lie, equivocate, be silent, or tell the truth in any given situation is often a hard decision. Duplicity can take so many forms and have such different purposes and results. Questions of truth and lying inevitably pervade all that is said or left unspoken in relationships, communities and societies. Sometimes there may be sufficient reason to lie -- but when? The major works of moral philosophy of this century are silent on the subject. Whilst lying may be excusable or seemingly inconsequential from the viewpoint of the person lying, for the person who is given false information about important choices in their lives, the lie may render them powerless or disadvantaged. Lies may also eliminate or obscure relevant alternatives, or affect the objective appraisal of costs and benefits.
St Augustine defined eight kinds of lie, from lies protecting innocence to deadly religious falsehoods. In between come lies which cause injury, white lies for the sake of smooth discourse and lies told for the sheer heck of it. In the past, Jesuits practised the art of equivocation, using the method of "mental reservation" (like crossing our fingers) to justify misleading statements. Heroditus, first branded a liar by Thucydides, was then called the Father of Lies by Oscar Wilde in his 1891 book The Decay of Lying.
"Scientific" signs of lying are blinking, nose scratching, dry mouth, high-pitched voice, dilated pupils, hesitation and fidgety feet. Folkloric give-aways are biting on your tongue while eating, a blistered or spotty tongue and knocking over a chair when getting up. The polygraph, or lie detector, has been discredited by the Lancet and shown to be more likely to implicate the innocent than catch the guilty. But in the USA it is used by the CIA, Army Intelligence, and the FBI, amongst others. The condition of pathological lying is called pseudologia phantastica. Sufferers often pose as authority figures.
Lying (whether in the form of outright untruth, exaggeration, understatement, omission, or 'white lies') is routinely used to manipulate the feelings and thoughts of others. It is also used in self-defence when people are confronted, and as a means of avoiding accountability. A British Telecom survey in 1990 found that seven in 10 secretaries were prepared to tell lies to cover for their employer. It may be essential to the process of selling goods and services, especially in encouraging people to purchase what they do not need. In many professions deception is taken from granted when it is felt to be excusable by those who tell the lies and those who tend also to make the rules. Government officials and those who run for elections often deceive when they can get away with it and when they assume that the true state of affairs is beyond the comprehension of citizens. Social scientists may condone deceptive experimentation on the ground that the knowledge gained will be worth having. Lawyers manipulate the truth in court on behalf of the clients. Journalists, police investigators, and intelligence operators often have little compunction in using falsehoods to gain the knowledge they seek.