Why is it important for characters to conceal the truth in order to maintain their social contracts?

In chapter 6, there were incidents of lying in the town. Dill lied about being near the Radleys house. Instead, he said that they were playing strip poker. He choose to do this to save the social contract that he had with the Maycomb society. It was known not to be near the Radley’s house as there have been rumours about them. If he didn’t lie, then his reputation in the society would significantly drop lower.

Also, Scout lied to Jem saying that she would tell Atticus that Jem was going to get his pance from the Radleys yard even though she didn’t. Scout didn’t tell because she didn’t want to ruin the friendly relationship and not being called a girl.