The main goal of this article is to present Negative Dialectics as a central theme in the Adorno’s thought. In this work Adorno develops the antinomies that there are in the concept of instrumental reason, in order to assert the necessity for a new notion of rationality: a dialectical, negative and materialistic reason, which holds, at the same time, the non identity between subject-object, thought and reality. In this way Philosophy becomes critique of Idealism because this philosophical system defends the (...) “identity thinking” and the irrational society that supports, making a true freedom impossible. Instead of this conception Adorno defines Metaphysics as “negative dialectics” and antisystem, whose method is the analysis of thinking’s models, as a result of his own critical epistemology. (shrink)