Abstract
In order to answer this question, it is necessary to first expose the core assumptions of Realism and Neo-realism. The main idea of classical realism is that the international system is anarchic, and therefore no higher controlling entity above states can exist to control them. In fact, states are the major rational actors of this system and they act towards their own national interests, which are security and survival. For classical realism, this characteristic derives from a certain perception of mankind as self-centred and competitive. The relations between states are thus determined by the resources they own and by the comparative levels of power. These assumptions are one of the reasons of the theory's success, as they have a strong empirical support in the international landscape at the beginning of the XXth Century, especially after the First World War and the failure of the League of Nations.
