The article includes two discourses: first discourse, discusses about modernity and two of its main foundations; rationalism and humanism, and then explanes their impacts on the formation of the modern world, society and human being. Second discourse, considers the postmodern critical approach to modernity and its principles. Postmodernism, totally rejects the modern reason and deconstructs all aspects of intellectual and rational legacy of the Enlightenment tradition and modernity. Finally, the author of the article concludes: negation of modern rationality as an instrument of total domination over contemporary and late modern society by postmodernism, denies the dichotomous quality of modern reason and refuses the emancipatory feature of the cultural and communicative reason, and as a results, leads to conservatism and nihilism.