Extended Intro/ overview of argument : The relative roles of Stalin and Truman were both influential in contributing to the politically turbulent circumstances of 1945-49 in the origins of the Cold war. The significance of their roles is primarily characterizied by the conflicting ideologies of Capitalism and Communism between the USA and USSR respectively. In assessing the importance of each leader, this explicit conflict was fuelled by the more influential concern of security and the way this idea manifested itself in terms of fuelling aggressive nature of policies on an individual basis and the perception of each country by the other on a global scale. This was pivotal in giving rise to the mutual suspicions and instability that characterized the early stages and influenced decisions made at events of Yalta, Potsdam, Truman Doctrine, Berlin Blockade. The debate to be had however calls for an investigation of the degree of responsibility and as such we must consider and assess the validity of the contrasting historiographical interpertattions of the orthodox, revisionist and post-revisionist schools of thought in trying to comprehend the origins of the Cold war. A detailed analysis of historian John Lewis Gaddis' cold war post-revisionist theory ultimately finds Stalin's paranoid and narcissistic pre-disposition regarding his obsession for security at all costs as not only reckless but the fundamental feature in serving to enhance predictable tensions in the US-Soviet relationship that had benn rooted since the Russian Revolution. The establishment of Cold War conflict transcends just geo-political differences and ideological dichotomy between states therefore. Rather, there must also entail a consideration of the individual actors at the heart of this tension through n assessment of the political psychology employed by both Stalin and Truman.