Why do we lie?

Learning to lie properly is an important feature of the process of human socialization, for we have innumerable good accounts of adults, in a wide variety of social and cultural contexts, exercising their social skills in telling the right lies at the right time, and to the right people.

In intimate face-to-face relations the shared expectation of mutual trust may lead to collaboration between, or more likely connivance by liar and dupes in order to maintain the plausibility or a lie, as well as the plausibility of continuing trust. When this happens it is no longer obvious who is deceiving whom.

Many peasant legal systems are likewise concerned with reaching acceptable compromise outcomes rather than arriving at some constituted truth, even when dealing disputes that are not centred on the family. ... They cared about ending conflicts, to forestall supernatural vengeance. The compromise solutions they reached 'may be based on outright lies, which everyone knows are lies but which offer the only possible route to agreement'.

Mediterranean societies, Peristiany refers to 'the defensive use of deception and the offensive use of ridicule', with secrecy as the other major defensive strategy used by families jealous of their honour.

In the defensive category are lies told to conceal an inability to live up to the highest requirements of the social code, either by oneself or by one's family, and those told to conceal unintentional failures, such as being poor or being turned down in a projected marriage match.

Men lie as a matter of habit and principle to deny other people information

Untruths provide weapons for the weak to resist the strong and for the strong to moderate the antagonism that their dominance provokes from the weak.

Self-deception promotes short-run psychological health and adaptive decisions. It also helps maintain the sociental status quo, thus promoting political stability. Long-run psychological health and beneficial social change, however, are thereby constrained.

"But as much as I wanted to be a detective and find him out, I didn't want to either. Because the truth, I was afraid more of the truth than living in the lie kind of."

The lie is a technique for the restriction of the social distribution of knowledge over time, and is thus ultimately woven into the system of power and control in society.

--J. A. Barnes.