how do historians interpret theses events? do they think they were necessary in order for the society to advance

No. The witch trials were an aberration and took a step backward in the advancement of society. They attempted to blame a scapegoat for society's ills. This theme was later repeated when the Nazis blamed the Jews for Germany's economic problems and Senator McCarthy blamed liberals for political problems.

ok....but indoing so (blaming a scapegoat for society's ills) how did it affect the society enough in making it take a step back?

If you want to read an excellent piece of fiction on this, read Arthur Miller's play "The Crucible". If you can find a copy with notes and commentary you'll learn plenty about the salem witch hunts. You'll also see how Miller compared/contrasted that event to the communist hearings of McCarthy which were taking place when that play was first published. Miller's very informative in my opinion.

Often it takes an atrocious event that shocks our conscience, and unsettles us so much that we are forced to confront the beliefs and demagogues that let to the event. Sometimes we adjust our behavior (and laws). Examples:
Holocaust
The witch persecutions and trials
McCarthy "communist" hunt
Killing of civil rights workers
Killing of abortion clinic workers
Attack on men, including killing
The shooting by the FBI sharpshooter Lon Horiuchi of a woman holding her baby at Ruby Ridge.
The overreaction of the ATF at Waco with the religous sect, and the subsequent actions of the FBI.
President Nixon's involvement in Watergate.

So, what I am relating, is that the witch persecutions were so blatantly wrong, we did step back, and rethink our basic precepts. History is full of examples. Remember, the witch persecutions in America can not be thought of separately from the witch persuctions in Europe, which had been going on for two hundred years. There are some pretty horrible descriptions of these recorded. http://www.gendercide.org/case_witchhunts.html

Who did the killing?

what was the outcome of the Salem witch trials

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The Salem witch trials resulted in the execution of 20 people, mostly women, and the imprisonment of over 200 people. The majority of those accused were found not guilty, but the trials had a lasting impact on the community and the nation. The trials also highlighted the dangers of religious extremism and the power of superstition.

During the Salem Witch Trials, it was the colonial government that conducted the trials and carried out the punishments. The trials resulted in the execution of 20 individuals, mostly women, who were accused of practicing witchcraft. Additionally, several others died while in jail, and many more were imprisoned or faced social restrictions. The outcome of the trials was a significant loss of life, shattered communities, and a general atmosphere of fear and distrust in the Salem Village. It was only after the trials that people began to question the validity and fairness of the accusations, leading to a gradual shift in public opinion and the eventual recognition of the injustice that had occurred. This event serves as a cautionary tale and reminder of the dangers of mass hysteria and the need for a fair and unbiased justice system.

During the Salem witch trials, it was the colonial government and legal system that conducted the trials and executions. The outcome of the trials was that 20 people were executed, 14 women and 6 men, and one man, Giles Corey, was pressed to death with heavy stones. Additionally, five other individuals died in jail while waiting for their trials, and many others were imprisoned or faced various forms of punishment. The trials eventually came to an end when the governor of Massachusetts, Sir William Phips, dissolved the Court of Oyer and Terminer in October 1692, and a higher standard of evidence was required for convictions. The aftermath of the trials saw a period of reflection and remorse, with efforts made to compensate the victims and their families, as well as the repeal of the witchcraft law in 1693. It is important to note that the Salem witch trials remain a tragic and disturbing chapter in history, reflecting the dangers of mass hysteria, religious extremism, and a flawed legal system.