This article seeks to answer the question that what the factual understanding is and how it is possible. The author’s hypothesis is that in the realist understanding, ‘causal explanation’ takes precedence over the ‘description’ (as is common in the hermeneutic outlook) and over the ‘prescription’ (as is prevalent in logical positivism). This article has chosen Hobbes’ Leviathan as the classical example of realist analysis and has founded its arguments on that everlasting work and explained them. On this ground, initially the key teachings of the realist school are described in the context of four categories, namely the conviction and truth, definition of positions based on power, according priority to political morality, and granting independence to the sphere of political action, and then methodological requirements of realism are offered. The author, in this section, refers to materialism, analysis and synthesis of statements, nominalist semiotics of concepts and finally the definition of conditions according to their antitheses, and concludes that Leviathan is though the most important reference in the modern political science, the book fails to deal with such issues as how such facts like national interests and the Leviathan’s interests are distinguished and separated. Other facts include how savage and wild human beings conclude and enforce a contract, and more importantly, whether the rationalist reason is reliable in justifying all human behaviors.
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