<P> The study of International relations as theory can be traced to E.H. Carr's The Twenty Years' Crisis which was published in 1939 and to Hans Morgenthau's Politics Among Nations published in 1948 . International relations as a discipline is believed to have emerged after the First World War with the establishment of a Chair of International Relations at the University of Wales, Aberystwyth . Early international relations scholarship in the interwar years focused on the need for the balance of power system to be replaced with a system of collective security . These thinkers were later described as "Idealists". The leading critique of this school of thinking was the "realist" analysis offered by Carr . </P> <P> However, a more recent study by David Long and Brian Schmidt in 2005, offers a revisionist account of the origins of the field International Relations . They claim, that the history of the field can be traced back to late 19th Century imperialism and internationalism . The fact that the history of the field is presented by "great debates", such as the realist - idealist debate does not correspond with the historic evidence found in earlier works: "We should once and for all dispense with the outdated anachronistic artifice of the debate between the idealists and realists as the dominant framework for and understanding the history of the field". Their revisionist account claims that up until 1918, International Relations already existed in the form of colonial administration, race science and race development . </P> <P> Explanatory and constitutive approaches in international relations theory is a distinction made when classifying international relations theories . Explanatory theories are ones which see the world as something external to theorize about it . A constitutive theory is one which believes that theories actually help construct the world . </P> <P> Realism or political realism has been the dominant theory of international relations since the conception of the discipline . The theory claims to rely upon an ancient tradition of thought which includes writers such as Thucydides, Machiavelli, and Hobbes . Early realism can be characterized as a reaction against interwar idealist thinking . The outbreak of World War II was seen by realists as evidence of the deficiencies of idealist thinking . There are various strands of modern - day realist thinking . However, the main tenets of the theory have been identified as statism, survival, and self - help . </P>

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