Did one 1648 peace treaty really invent the modern state?

Textbooks often say yes. They say that the Peace of Westphalia, signed in 1648, created the idea of sovereign states with fixed borders, each master of its own territory and equal to all the others. Most modern historians now disagree, calling the story the "Westphalian myth", and the disagreement is a good way to learn what sovereignty is.

First, what was signed. Two treaties, concluded in October 1648, ended the Thirty Years' War and brought peace to the Holy Roman Empire, after a catastrophe that killed between 4.5 and 8 million people. Among other things, the treaties said that princes could no longer dictate their subjects' religion. They also confirmed that the Swiss Confederacy was legally independent of the Empire.

Next, the idea attached to the treaties. Westphalian sovereignty is the principle that each state has exclusive sovereignty over its territory, and that every state, large or small, has an equal right to it. Some scholars of international relations trace it to 1648. But the text of the treaties contains nothing about sovereignty as a principle. The historian Andreas Osiander writes that the treaties confirm no one's sovereignty, least of all as a principle. Other scholars argue that the treaties actually limited the sovereignty of many states inside the Empire.

So the modern view runs like this. The treaties did not invent the modern state system. They symbolize the end of a long period of religious conflict. The story that they founded the state system seems to have grown later, during the nineteenth and twentieth centuries, when people were worrying about sovereignty. Even so, the story has shaped how people think about borders: the idea that a line around a territory marks where one authority ends and another begins.