Fear is the root of every conflict in The Crucible. The girls lie because they're afraid of being punished. Parris contributes to the lies because he's afraid he'll lose his position in the town. The Putnams lie--she because she's afraid her stillborn babies dying might have been her fault, he because he's afraid he'll lose his land and reputation/position in the town. Abigail lies because she wants John for herself and is afraid he won't have her. Tituba lies because she fears she'll be the scapegoat for everything if she doesn't. Elizabeth lies because she loves her husband and is afraid he'll be punished. There are consequences to each of these lies, all rooted in fear, and together they create the conflict in this play.
Fear causes people to react in ways that ensure their personal safety. In most situations, protecting oneself means going against someone else, creating conflict. As stated in post #3, this can be seen most clearly in the Crucible by the girls blaming others to keep from having punishment come on them. Furthermore, townspeople confessed to what they knew were lies, preferring to be named a witch and reconciled to the town than to be hanged. The problem is that the more the people confessed, the more people were accused, creating a vicious cycle that took radical means to stop.
The most significant example is Abigail. She and the other girls were caught in their forest pursuits, creating a conflict where they faced severe punishment. The fear they felt about this conflict compelled them to make witchcraft accusations against their neighbors, setting off a crisis in the township. Once the fire was lit, the fear spread throughout the town. Canny observers saw how easy it became to accuse someone, so old conflicts became fodder for accusations, spreading the conflagration.
Fear was one of the greatest weapons use din oppressive regimes. If people were afraid, they would be helpless, requiring protection from some other force, notably government.
In the play "The Crucible" by Arthur Miller, fear is used successfully as a weapon to keep people imprisoned in a culture that needs progress. In the end, where fear was used on Proctor to get a confession out of him, he refuses.