Say your boss has been taking longer than usual to respond to your e-mails. Many people would take that as a sign that their star is falling because if your star is falling, the chances are high that your boss will respond to your e-mails more slowly than before. But your boss might be slower in responding because she is unusually busy or her mother is ill. And so the chances that your star is falling if she is taking longer to respond are much lower than the chances that your boss will respond more slowly if your star is falling. The appeal of many conspiracy theories depends on the misunderstanding of this logic. That is, it depends on confusing the probability that a series of events would happen if it were the product of a huge conspiracy with the probability that a huge conspiracy exists if a series of events occurs. The effect on the probability that an event will occur if or given that other events occur is what Bayes's theory is all about. To