Because it is concerned with power, realism has tended to focus more on high politics than low politics. Realism has traditionally focused on power, and in the Westphalian state system, the state is seen as having the most power. However, for an interesting look at the worldview that shaped Thucydides' writing, see RG Collingwood's 'The Idea of History.' From this comes the quote 'The strong do what they have the power to do and the weak accept what they must,' expressing the realist theme of might-equals-right. Realists often credit Thucydides as the first realist thinker for his desire to leave an account of war as a 'possession for all time,' his writing style in which he was only concerned with facts from reliable sources, and for his concentration on power in 'The History of the Peloponnesian War.' The Melian Dialogue is often given extra attention due to the unique use of dialogue, leading many to believe that Thucydides is trying to highlight an important event. Carr's 'The Twenty Years' Crisis, 1919-1939' (he uses the term 'utopianism' for 'liberalism') or in Hans Morgenthau's 'Politics Among Nations.' An excellent discussion on the differences of the natures of these two theories can be found in Edwards H. Realist theory, however, focuses on the ways and means that states interact. Liberal theory is often marked by an analysis of an ideal, or utopian, outcome. The two modern major schools of International Relations theory are International Liberal Theory and International Realism Theory. However, the New World Order of the post-Cold War state system has required a redefinition of actors.

The study of International Relations has been, until very recently, the study of how states interact with other states. It was hoped that by studying how countries interact with each other, it would be easier to predict what the reactions of the United States or Soviet Union would be in any given situation, making it easier to avert war. Many political scientists feared that the Soviet Union and the United States would launch themselves into a global nuclear war.

The study of International Relations in political science gained strength during the Cold War.

Best international relations books 2013