<P>Hans Morgenthau¿s <EM>Politics Among Nations</EM> is a classic of political science, built on the firm foundation of Morgenthau¿s watertight reasoning skills.</P><P>The central aim of reasoning is to construct a logical and persuasive argument that carefully organizes and supports its conclusions ¿ often around a central concept or scheme of argumentation. Morgenthau¿s subject was international relations ¿ the way in which the world¿s nations interact, and come into conflict or peace ¿ a topic which was of vital importance during the unstable wake of the Second World War. To the complex problem of understanding the ways in which the post-war nations were jostling for power, Morgenthau brought a comprehensive schema: the concept of ¿realism¿ ¿ or, in other words, the idea that every nation will act so as to maximise its own interests. From this basis, Morgenthau builds a systematic argument for a pragmatic approach to international relations in which nations seeking consensus should