The study of world political power and international conflict, cooperation and peace. The discipline began in the 19th century and has grown rapidly, partly because of the development of atomic weapons and globalization of trade and communications, and partly because it has been viewed as a useful and valuable field of inquiry by many countries. It has been seen as a necessary complement to domestic politics and has become increasingly popular. It is also the subject of much normative speculation.
An important principle in this field is the idea of sovereignty, that each country has a sovereign right to control its territory and that no one country can claim exclusive ownership of the earth’s atmosphere, the high seas or Antarctica. It also implies that a country has the right to make its own alliances and to impose its own laws on other countries.
This idea has given rise to a range of theories of the nature of international relations. Marxist ideas have been particularly influential and hold that world political affairs are the outcome of economic classes in a struggle for resources and market access. These theories also tend to assume that the economy trumps all other concerns and that national governments are motivated by the desire for capital accumulation.
There are also Americanist and Globalist approaches to the study of international politics. The former see the indisputable first objective of the United States as safeguarding liberty, security and prosperity at home while extending that zone to the rest of the world. The latter see the goal as promoting democracy, human rights and free enterprise throughout the world.