Puritan society required that its members follow strict guidelines of social order. These rigid rules of conduct helped the Puritans endure the persecution they faced in Europe and, after they came to America, created a close-knit community able to withstand the harsh weather and Native American attacks common to New England in the 17th century. But communities that focus primarily on social order leave no room for personal freedom. Those who think or act independently are seen as a threat to the community: they must therefore be swiftly stopped or eliminated.
An excessively strict social order also provides no outlet for personal grievances. Over time, unvoiced resentments build up among individuals, primed to explode. The witch trials depicted in The Crucible can be considered an attack against individuality: those accused and convicted of witchcraft were mostly people who prioritized their private thoughts and integrity above the will of the community. The trials provided a legally sanctioned forum for the expression of anger and grievance. If your neighbor once sold you a pig that died soon after you bought it, and that neighbor stands accused of witchcraft, it seems only natural to bring up the dead pig as possible evidence. The trials also gave people like the Putnams to chance to voice their festering bitterness by accusing those whom they had quietly resented for years.
In The Crucible, neighbors suddenly turn on each other and accuse people they've known for years of practicing witchcraft and devil-worship. The town of Salem falls into mass hysteria, a condition in which community-wide fear overwhelms logic and individual thought and ends up justifying its own existence. Fear feeds fear: in order to explain to itself why so many people are afraid, the community begins to believe that the fear must have legitimate origins.
In The Crucible, hysterical fear becomes an unconscious means of expressing the resentment and anger suppressed by strict Puritan society. Some citizens of Salem use the charge of witchcraft willfully and for personal gain, but most are genuinely overcome by the town's collective hysteria: they believe the devil is attacking Salem. And if the devil is attacking your town, then ensuring that your neighbor is punished for selling you a sick pig suddenly becomes a religious necessity, a righteous act that protects the God you love and proves that you're not a witch or a devil-worshipper. The Crucible shows how religious fervor fuels hysteria and leads to conditions that sacrifice justice and reason.
An ideology is a rigid set of beliefs that defines what an individual or community thinks. In the Puritan theocracy of Massachusetts, a government run by religious authorities, the dominant ideology held that the Puritans were a chosen people that the devil would do anything to destroy. Since religious men ran their government, the Puritans considered all government actions to be necessarily "good," or sanctioned by Heaven. This meant that any attempt to question, obstruct, or otherwise resist any of the government's actions, no matter how ludicrous, destructive, or ill-informed, was considered by the government and other Puritans to be an attempt to overthrow God.
Governments fueled by such rigid and absolute ideological convictions often fall into corruption and tyranny without even realizing it. In The Crucible, Deputy Governor Danforth and Judge Hathorne believe that they're emissaries of God, and therefore that everything they believe must be true and everything they do must be right. They never see a reason to reassess their thoughts and actions, which makes them easy targets for cynical and talented liars like Abigail Williams. Characters like Abigail recognize the court's narrow-minded worldview and manipulate it to their own selfish advantage
Reputation is the way that other people perceive you. Integrity is the way you perceive yourself. Several characters in The Crucible face a tough decision: to protect their reputation or their integrity. Parris, Abigail, and others to protect their reputations. Rebecca Nurse and, eventually, John Proctor, choose to protect their integrity.
In rigid communities like Salem, a bad reputation can result in social or even physical punishment. The Crucible argues that those most concerned with reputation, like Parris, are dangerous to society: to protect themselves, they're willing to let others be harmed and fuel hysteria in the process. In contrast, The Crucible shows that those who favor integrity by admitting mistakes and refusing to lie just to save their own lives help defy hysteria. Willing to die for what they believe in, they put a stop to the baseless fear that feeds hysteria.