Codgers, bugs, crackpots, neurotics, kooks, cranks, crazies, headcases, fools, fruitcakes, tykes, sickies, deviants, nutters, loonies, lunatics, madmen, sociopaths, maniacs, obsessives, psychos, paranoids, quizzes, oddballs, schizos, wackos, lunatics, weirdos, abnormals and zanies, human creativity knows no limits when it comes to finding names for those people who are thought to be just a little bit off. But what exactly do we mean to say when we call someone mad? And what can philosophy teach us about this?