Chapter 6 demonstrates how the vicious argumentative circle of the controversy on the conception of nature between scientific realism and cultural constructivism can be overcome with the help of relational pragmatism. Drawing upon Dewey’s work and laboratory studies (Knorr-Cetina; Pickering), this chapter introduces the concept of ‘experimental interactivity’. It is used to characterize the particular way in which interrelations between subjects and objects, between human culture and non-human nature are mutually establishing. The fruitfulness of this pragmatist conception is illustrated by an ethnographic field study dealing with different cultures of experience and knowledge over several years. It demonstrates how in Bangladesh both the hydraulic engineers from the West and the indigenous river islanders are learning to interact with the unpredictable subject-like character of the Jamuna River confronting them with catastrophic floods and relocations.