By what right does a government collect taxes? What distinguishes such taxation from robbery at the point of the sword? These are abiding questions in political philosophy. In his great apologia for Christianity, The City of God, Augustine of Hippo tells the apocryphal story of a pirate captured and brought before Alexander the Great.When theMacedonian ruler asked him how dare he keep hostile possession of the sea, the pirate replied, “How do you dare to seize the whole earth? Because I do it with a petty ship, I am called a robber, while you who does it with a great fleet are styled emperor?”

This is a profound and difficult question. Answering requires the concept of political legitimacy. Principles of legitimation vary widely across societies. The president of a modern democracy might respond to the pirate's question by saying: “Because I was elected by the people in a democratic election.” An Egyptian pharaoh might answer by saying he was the embodiment of Horus and the son of Ra. A legitimate government is one that is perceived to be so. That is, the legitimation principle has to cohere with the belief systems of the population. An American presidential candidate who claimed to be the embodiment of Horus would not get very far. This is because today the most important source of legitimacy is democratic. Prior to 1800, however, the most important sources of legitimacy were religious.

The significance of religion as a source of political legitimacy was a key feature of medieval societies in both Europe and the Middle East. Modern anthropological research shows that rulers of the earliest known states all based their authority on the claims of religion. In the Egyptian case, scholars have documented that “the Egyptian conception of kingship was that the king was a god – not merely godlike, but the very god” (Fairman, 1958, 75).