There are social tensions in all societies, but they can be particularly acute in small-scale communities such as Salem, which have limited contact with the outside world. Salem was a very enclosed community, whose townsfolk regarded themselves as a class apart from other people.
There was a particularly fierce rivalry between Salem Village—where the witch-craze took place—and the more affluent community of Salem Town. This high degree of social antagonism may not have caused the witch-craze, but it certainly helped to generate the conditions for its eventual outbreak.
With such tensions in the air, people in this part of the world were already atomized into distinct units without any enduring social bonds to hold them together. So when the Salem witch-craze began, it was very much a case of every man for himself, with the already tenuous bonds of society being torn asunder in the midst of a veritable frenzy of false accusations.
Resentment towards the well-heeled folk of Salem Town was turned inwards as the people of Salem Village became insanely suspicious and fearful of each other. The people of Salem had been afraid of outsiders for so long—whether it was rival villages or Native-American tribes—that it was only a matter of time before they started fearing each other. All it took was the single spark of a false accusation of witch-craft to light the flame of mass hysteria that would rage on for several months.