Realism is one of the most influential perspectives on international relations especially in the United States since the end of World War II. Realism has its intellectual roots in the conservative social and political philosophy. Therefore, in the quest to have it’s deeper understanding, it’s important to appreciate its conservative foundations. The pessimistic view of human nature is one of the critical elements of social and political philosophy. This element holds the view that people are flawed, imperfect, and imperceptible creatures. Human nature is a mix of good and bad features, and the latter can never be completely eliminated.