most humans believe in invisible beings called “ghosts,” or “spirits,” or “gods.” Many spend vast amounts of time thinking about these beings and attempting to communicate with them telepathically, and many gather together regularly to perform costly and elaborate rituals, aimed at persuading the beings to be nice to them. On top of that, many make strenuous efforts to persuade others to believe in the invisible beings and to engage in the costly rituals. And they do all of this despite a relative paucity of evidence that the invisible beings exist or that the rituals actually work.