After situating the figuration of the postdevelopmental child in the context of hegemonic colonising developmental discourses about child rearing and education, I engage with posthumanist perspectives that rupture the binaries, power relations and age discrimination these discourses assume. Developmentalism raises concerns about how child as knower is positioned. Drawing on the ground-breaking work of feminist philosopher and quantum physicist Karen Barad, an affirmative diffractive methodology is used with two approaches to teaching and learning: Reggio Emilia and Philosophy with Children (P4C). Through the experimental diffractive reading of the rhizomatic concept development that is core to both educational philosophies, new ideas are proposed for postdevelopmental curriculum construction. A new pedagogical practice of working with concepts is created, thereby deterritorialising what conceptual knowledge is. By putting philosophy at the heart of deterritorialising knowledge, room is made for children as knowledge producers, rather than knowledge consumers.