Abstract: The subject of this research is the methodology of postmodernism. The goal of this work is to examine the diverse postmodern views and ideas as a uniform cognitive system and conduct its critical analysis. The article provides brief description to the establishment of postmodernism as a social theory. The research presents the author’s outlook upon determination of the methodological principles of fallibilism, discursiveness, deconstruction, deprivileging of science, approach and method, as well as life-affirming humor. Within the framework of studying the principle of discursiveness, an attempt is made to give a generalizing interpretation to the categories of discourse, text and narrative. Criticism of methodological principles of postmodernism includes their cognitive idea, merits and demerits in contrast to the modernistic social theories. A conclusion is made on correlation and complementing interaction of the highlighted by the author generalized methodological principles of postmodernism. An assessment is given to the cognitive capabilities of postmodernism as a social theory overall. The performed methodological analysis may commence a broad discussion on the role and place of postmodernism as a cognitive theory of modern society.