The emergence of Large Language Models has exposed composition studies' long-standing commitment to Cartesian assumptions that position writing as a nonmaterial, distinctly human activity. This paper develops a naturalized theory of composition grounded in Deweyan pragmatic naturalism that dissolves the nature/culture dualism embedded in contemporary theory and practice. We advance an eco-ontological account that understands compositional activity as emerging from within the matrix of animal behavior and introduce "compositional viability" to theorize how writing functions as a biosemiotic tool for environmental reconstruction. This framework yields three pedagogical implications: attending to somaesthetics, cultivating writerly habits, and orienting composition toward viable action.