Everyone has heard of the term "pseudoscience", typically used to describe something that looks like science, but is somehow false, misleading, or unproven. Many would be able to agree on a list of things that fall under its umbrella-- astrology, phrenology, UFOlogy, creationism, and eugenics might come to mind. But defining what makes these fields "pseudo" is a far more complex issue. It has proved impossible to come up with a simple criterion that...