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Arthur Miller's The Crucible is one of those wonderful/terrible works of literature with countless levels of meaning. Certainly the story itself stands as one level. It is mesmerizing, suspenseful, mysterious, and shocking.
The historicity is an accurate representation of what happened in Salem, MA between 1692 and 1692. People decried common sense and rational evidence as a reaction to fear of something they didn't understand.
Miller, as you may know, actually wrote the play during the years when people in the US had an deep-abiding fear of communism. The Cold War was a terrifying time in US history because no one really knew what may happen if the Soviet Union determined to attack the US. As a result, anyone who showed any kind of sympathy toward communists or who held ideals that might have been construed as "communist" were labled as "un-American" and often lost their livelihoods. Senator Joe McCarthy was the de facto leader of the movement which, like the with trials of Salem, relied on rumors and fears rather than reason and facts.
At this point, you may see just how this play still relates to society. How many current events are inflamed or even caused by someone's irrational fears, rumors, or false assumptions? Political, sports, and entertainment figures are frequently victims of rumors that cost them both money and reputation. (See rumors of "doping" by cyclist Lance Armstrong as one example of how hard it is to redeem a reputation sullied by false accusations.)
In current society, people are quick to react rather than thoughtfully and rationally respond. Whether it is a political vendetta or an accusation of wrong-doing, emotional reactions are often quick and powerful. With a 24 hour news corps, emotions are often reported as fact in order to "scoop" other media. Once reported, "news" is spread quickly (Michael Jackson's recent death is an example) via Twitter, Facebook, and other similar newtworks. Whether the news is accurate is rarely verified. Retractions are usually buried (if they are published at all.) People then respond with a mob mentality before all the facts are truly understood. Of course, the Salem trials often led to execution, which allowed for no redemption.
Since society is made up of individuals, it follows that, even without the influence of a mob mentality, it is easy to react first and think about it later. Visceral emotions are tied to fears, usually of the unknown or unfamiliar. When a thing is unknown, the reasonable and rational response is to stop and gather information. Fear, however, often causes individuals to lash out emotionally, sometimes causing irreparable hard to others.
Miller understood humanity's need to understand as well as he recognized humanity's fear of the mysterious. Whether the reaction is related to historical events of the 17th century, political fears of the mid-20th century, or personal insecurities about the unknown, it is far better to respond to the facts rather than react to the fears.