Back in the 1950s three social psychologists joined a cult that was predicting the imminent end of the world. Their purpose was to observe the cultists’ response when the world did not, in fact, end on schedule. What they discovered, and described in their classic book, “When Prophecy Fails,” is that the irrefutable failure of a prophecy does not cause true believers — people who have committed themselves to a belief both emotionally and by their life choices — to reconsider. On the contrary, they become even more fervent, and proselytize even harder.