A thing is not true simply because a large number of people believe in it. This is a prominent theme throughout the Crucible when accusations of witchcraft and inculcations of devil-associating that are known by the reader to be simply conjurations of the people’s imaginations or greedy attempts to gain land or enact vengeance upon one’s enemies, are taken as truth and believed by most of the town. So many people believe the wild accusations, or at least play along with them, that everyone except the actual victims are beguiled.
One instance from the Crucible where everyone accepts something to be true because so many people already seemingly believe it is right after John Proctor has defamed himself in front of the court but his wife Elizabeth accidently denies it, seeking to save his name. The wily Abigail is beguiling the court with false accusations stating that Mary Warren has “sent her spirit out” and conjured a bird. “(Abigail, with a weird, wild, chilling cry, screams up to the ceiling.)…Danforth: what is it child? (But Abigail is now raising …her awed face to the ceiling –the girls are doing the same- and now Hathorne, Hale, Putnam, Cheever, Herrick, and Danforth do the same.)” With Abigail’s wild gesticulations and quavering wails she sways the majority of the court into believing Mary Warren is committing witchcraft.
Events like this occur throughout the Crucible, sometimes at the hand of Abigail but other times through others. You, the reader, know that it’s all one big myriad of lies that has snowballed out of control but everyone excluding the accused and Reverend Hale believe them. These events display the previously stated theme that a thing is not true simply because a large number of people believe in it.