This paper introduces and develops the concept of autonegation, a new philosophical term within the framework of Metamonism. Autonegation describes the self-directed negativity of Chaos, where negativity itself becomes negative toward itself, producing the first act of differentiation without requiring an external agent, substance, or metaphysical ground. Building on the proto-ontology of Chaos–Logos, the study shows how autonegation provides both an ontological basis for difference and a methodological key for unifying diverse scientific domains. By reframing the origin of difference, time, and structure as emergent from autonegation, the article positions Metamonism as a self-justifying, reflexive system and proposes its significance for contemporary philosophy, mathematics, physics, and cognitive science.