Human beings are skeptical of coincidence, and think in terms of cause-and-effect, which is why many people are attracted to conspiracy theories to explain seemingly inexplicable events, like the assassination of a U.S. President. Susan Spencer talks with spy novelist Gayle Lynds and psychologist Rob Brotherton about humans' propensity to seek out clandestine, nefarious plots, and with professor Joseph Uscinski, who has studied hundreds of bizarre theories, and who thinks a little dose of conspiracy-thinking actually may be good for democracy.