As many others have pointed out, Machiavelli is unique in being the first (known) political thinker to consider the modern idea of the nation-state and the notion of sovereignty. However, there is another important distinction to make.
While there were other post-Hellenic philosophers who wrote in the field of politics (Augustine may be one), these were all philosophers first who arrived at political theory only as a consequence of their politics. Machiavelli, on the other hand, was the first to approach political science as a independent discipline, concerned with the art of politics rather than the ethic
It could be argued that a political orientation that favors social progress by reform and changing laws rather than by revolution is called "liberalism," although it should be noted that some extreme liberals can be in favor of revolution as well.
