History often repeats itself. This means that, because people throughout time are generally similar, and have the same dreams, goals and ways of thinking, they often react in similar ways to similar situations.
In the case of the Salem Witch trials, people were convinced that the girls and women involved were victims of witchcraft, and that the best way of dealing with them was to burn them alive. This was a result of religious fanaticism and prejudice towards those who are different.
Another example of mass hysteria was the persecution of communists during the McCarthy era. During these years, people were similarly obsessed with an ideological position: that communism was bad for the nation. Therefore, they persecuted those who they believed exhibited behaviour that was not American or patriotic.
Finally, an older example would be the persecution of Jewish people during the years of the Black Death. As people were unaware of the causes of the disease, they were looking for someone to blame for it. They used their already preconceived bias against Jews in order to blame them and persecute them, regardless of the lack of evidence against them.
