The starting point of this volume was the notion of the co-production of science, technology and society. Scientific knowledge and technological systems on the one hand and social, political and moral relations on the other hand are mutually constituted in one and the same historical process. This constructivist notion implies, first, a denial of any kind of autonomy of knowledge, power or morality. Cognitions, social relations and moral rules co-develop. Second, the notion of co-production rejects any kind of reductionism or determinism. Developments in science and technology cannot be explained exclusively by their social and political context. But neither do science and technology determine our condition humaine. Technological means and human ends, instruments and interests, artifacts and desires – all are co-produced. Analytical priority is denied, both to technology and to humanity.

Thus, from the very start, two positions are eschewed: a humanistic voluntarism pronouncing that man is the measure of all things, and a technological determinism preaching that technology follows its own immanent logic. Instead, following the principle of radical symmetry, both humans and nonhumans are granted agency. Or, more adequately, since agency is not an a priori quality of entities-in-themselves, but the result of developments in the hybrid networks of humans and nonhumans, the distribution of agency is analysed. Agency is every inch a relational characteristic – not the condition for, but the product of contextually situated, relatively contingent developments. This notion of relational and distributed agency is used by Disco in his attempt to integrate science and technology studies with general social theory; by Brey in criticising realism for its blindness to social representations and social constructivism for its neglect of “objective” physical constraints; by Oudshoorn et al. in uncovering inequalities in the design and use of a specific technological artifact; by Stemerding and Nelis in analysing the construction of different subject-positions in medical screening programs; and by Popkema and Harbers in detecting incongruencies between (sub)politics incorporated in a prenatal test and governmental policies toward the same test. Central to all these contributions is not what humans and nonhumans (essentially) are, but what they do – among themselves and vis-à-vis the other, without presupposing in advance any hierarchy between them. Ergo, the volume is tuned in a poststructuralist and a posthumanist key.