Secession has been a hot topic in 2017. At least two important plebiscites have been celebrated: Kurdistan and Catalonia. Predictably, both the governments of Iraq and Spain have strongly condemned them as illegal, respectively. Both governments are right: the laws of both Iraq and Spain do not allow for secession in the terms that the plebiscites propose it. But, then again, basically no country in the world (Ethiopia and Canada being notable exceptions) accepts the legality of secession. Yet, throughout history, secessions have happened multiple times. Technically, almost all of them have been illegal. Morally, some of them have been celebrated, some not. What, then, is the criterion to judge the morality of secession? What makes George Washington a hero, but Jefferson Davis a villain (if at all)?