Realism is a theory that suggests the need for anarchy in the global arena, while at the same time realist doctrine suggests that stability can only be achieved through a “balance of energy". That said, the doctrines of Collective Security and Defense are fundamentally different from realism or the idea of ​​a “balance of power” means that even the anarchic law of Realism is destined to seek order or at least is at the mercy of its necessity? It is hoped that the evaluation of the limits of realism and the examination of the “practiced” institutions of collective security and defense can therefore clarify this essential point in order to understand the differences between them and the possible related factors needed in the overall evolution of Realism/Neorealism Realism, as defined, actually applies to pretty much anything. Whether we are talking about science, mathematics, ethics, or politics, the nature and application of realism can be applied. Therefore, it is essential to narrow the scope of individual study of realism. For the purposes of this article, the focus will remain on realism solely in terms of its application to international relations of which it appears to be the most dominant theory.1 Also called “political realism,” its antithesis is generally considered to be liberalism. Political realism emphasizes the conflictual and competitive nature required of states seeking to remain stable and continually evolving positively. In contrast, liberalism suggests the need for cooperation between states.2 The determining factor then in realism is the ever-present need for a state to look after its own well-being while promoting its own... medium... . ..exists in everything as an integral and dominant aspect of humanity. Works Cited “Collective Security.” University of Colorado Boulder. http://www.colorado.edu/conflitti/peace/treatment/collsec.htm (accessed May 27, 2011).Gallis, Paul E.. “USIA – NATO: Article V and Collective Defense.” Federation of American Scientists. http://www.fas.org/man/crs/97-717f.htm (accessed May 27, 2011).Kemos, Alexander. "Thucydides in the Modern World." HR-Net home page. http://www.hri.org/por/thucydides.html (accessed 27 May 2011). “Political Realism in International Relations (Stanford Study of Philosophy).” Stanford Encyclopedia of Philosophy. http://plato.stanford.edu/entries/realism-intl-relations/ (accessed May 27, 2011). “Realism (Stanford Study of Philosophy).” Stanford Encyclopedia of Philosophy. http://plato.stanford.edu/entries/realism/ (visited May 27, 2011).