Derrida identifies a "logocentrism" or privileging of speech in Western philosophy. Logocentrism holds that words express an external reality and that thought is derived from speech. Derrida criticizes logocentrism for relying on unexamined metaphysical assumptions about the relationship between language and reality. He questions the "metaphysics of presence" underlying logocentrism by exploring how meanings shift within linguistic systems. Critical examination of logocentrism is really about attentiveness to how specific languages materially shape communication and understanding.