A Discussion of International Relations.

The history of international relations is often traced back to the Peace of Westphalia of 1648, where the modern state system was developed. Prior to this, the European medieval organization of political authority was based on a vaguely hierarchical religious order. Westphalia instituted the legal concept of sovereignty, which essentially meant that rulers, or the legitimate sovereigns, would recognize no internal equals within a defined territory and no external superiors as the ultimate authority within the territory's sovereign borders. Classical Greek and Roman authority at times resembled the Westphalian system, but both lacked the notion of sovereignty.

Westphalia encouraged the rise of the independent nation-state, the institutionalization of diplomacy and armies. This particular European system was exported to the Americas, Africa, and Asia via colonialism and the "standards of civilization". The contemporary international system was finally established through decolonization during the Cold War. However, this is somewhat over-simplified. While the nation-state system is considered "modern", many states have not incorporated the system and are termed "pre-modern". Further, a handful of states have moved beyond the nation-state system and can be considered "post-modern". The ability of contemporary IR discourse to explain the relations of these different types of states is disputed. "Levels of analysis" is a way of looking at the international system, which includes the individual level, the domestic nation-state as a unit, the international level of transnational and intergovernmental affairs, and the global level.

What is explicitly recognized as International Relations theory was not developed until after World War I, and is dealt with in more detail below. IR theory, however, has a long tradition of drawing on the work of other social sciences. The use of capitalizations of the 'I' and 'R' in International Relations aims to distinguish the academic