The doctrine of "reason of state" is a slippery concept to define, having been used by many writers with different shades of meaning. In general, it refers to the idea that the well-being and stability of the state is paramount, and all of the government's actions should be directed to this end. This includes actions which would be considered illegal or immoral under ordinary circumstances. Machiavelli did not invent this doctrine, which can be found in the writings of many Classical authors, most notably, Tacitus. Machiavelli probably derived it from his study of Livy, Xenophon, and Aristotle. In fact, Machiavelli does not use the phrase "reason of state," which was first popularized by fellow Italian Giovanni Botero in his 1589 book, Ragione de Stato. Nonetheless, Botero's book draws heavily on Machiavelli's ideas, and Machiavelli is usually credited as the first modern writer to systematically describe the principles of reason of state.
Implicit throughout The Prince is the notion that almost any action of a ruler is justifiable if it contributes to the peace, prosperity, and stability of the state. Machiavelli endorses murder, deceit, violence, and cruelty, provided they are directed toward the greater good. He applauds Cesare Borgia's cruelty in subduing the Romagna because it ultimately brought peace and safety to the previously lawless region. In Machiavelli's defense, he does not endorse deceit or violence for its own sake. He assumes that there is a basic level of violence and injury that rulers cannot avoid. The key is to make the best use of this unavoidable cruelty. Actions that injure a few are better than actions that injure many. This principle can be seen in his discussion of colonies as a means of subduing a newly conquered territory. Colonies deprive a few people of their lands and homes, but they are preferable to occupation by an army, which injures and offends everyone in the territory. The greater good is clearly a consideration here. However, Machiavelli also makes clear his other primary consideration: The people who are injured by colonies are too few, too poor, and too scattered to pose any threat to the ruler who abuses them, while entire populations that hate and despise the new ruler are a definite threat to that ruler's continued power.
