As two famous exponents of poststructuralism, Jacques Lacan and Jacques Derrida have had a profound influence on modern philosophy, literature, cultural and social sciences. They both criticized classical ideas about language and consciousness, proposing new approaches to the analysis of linguistic and cultural practice. One of Lacan's main contributions to poststructuralism was his use of psychoanalysis to analyze linguistic structures. He developed the concept of the “speech act,” in which language is perceived as a manifestation of the unconscious, and not simply as a set of symbols and signs. Lacan argued that linguistic signs are symbolic in nature and they are associated with unconscious, hidden meaning. He also emphasized that linguistic signs and symbols can vary depending on the context and social practices that determine their meaning. Lacan also developed the concept of the "mirror stage", in which the young child begins to perceive his image in the mirror as a separate reality, separate from his own body. He argued that this process is key to the formation of individual personality and creates the illusion of unity and integrity. However, Lacan also emphasized that this illusion is unstable and is disrupted in the unconscious. Derrida, on the other hand, focused on the criticism of classical philosophy and explored the foundations of linguistic and cultural practice. He proposed the concept of "deconstruction", which consists of analyzing how language creates and maintains binary oppositions, such as spiritual and material, real and ideal, nature and culture, etc. Derrida argued that these oppositions are not absolute, but rather originate from different cultural and historical contexts. He proposed to "deconstruct" these oppositions, revealing their hidden assumptions and ambiguities. He also criticized the concept of presence, which argued that reality could be fully present and accessible to linguistic representation. Thus, both philosophers criticized traditional ideas about language and consciousness and developed new approaches to the analysis of linguistic and cultural practices. They both believed that language and culture are not neutral or transparent, but rather reflect certain power relations and ideological assumptions. However, Lacan and Derrida also differed in their approaches and emphasized different aspects of language and consciousness. Some critics point out the limitations and difficulties of applying Lacan's and Derrida's concepts in practice and scientific research. Some accuse them of focusing too much on language and ignoring other factors such as material conditions, social relations and political structures. However, their theories and concepts continue to influence modern philosophy, literature, art and social sciences, sparking debate and new research in the field of language and culture.