Essentially, we lie to avoid pain or anticipate pleasure.
Some lying generally is considered harmless. A white lie, for example, is a harmless fib that is meant to be tactful or polite. You have told a white lie if your wife proudly asks what you think of her new, ugly dress and you say, “I really like your new dress, honey.” It is said that a white lie may set the stage for lies of darker hues. Just after complimenting your wife on the ugly dress, she might say, “I'm glad you like the style. These dresses are on sale at the mall. Do you mind if I pick up two more in different colors?” Defensive lying is to deceive another person because the other person is trying to take advantage of you. If a mugger demands your wallet, you might lie by telling him that you don't have any money. (You also can use this response if your wife asks about buying more ugly dresses.) If a car mechanic quotes you $750 to replace a water pump, you might tell him that the place across town will do the job for $650, even if you don't know this to be true.