Roman dictators were temporary rulers appointed to protect the state during a war or other emergency. Many countries have laws that allow a similarly time-limited dictatorship, to fight against such problems. Karl Marx has the idea of the Dictatorship of the proletariat. When they became independent in the 1960s and 1970s, many African states changed to be dictatorships, run by one person. Karl Popper distinguished between two different forms of government, "Those where it is possible to change the government without bloodshed, in a popular vote, and those where it isn't." He said that this was the key difference, and not how the forms of government are named. 