Abstract

This paper discusses the operations meant to act on situations of ontological uncertainties for chemicals. Using examples related to substances developed as part of nanotechnology programs, it analyses technical and social instruments meant to define the existence of these substances, as « new » or « existing » chemicals. Carbon nanotubes developed by a French company offer an illustration of containment, while the legal disputes about nano silver in the U.S. display oppositions about whether or not these compounds are equivalent to colloïdal silver. The operations meant to deal with the ontological uncertainty of these substances define categories and craft political organizations. As such, they suggest developing an analytical approach able to jointly examine the ontologies of material objects and the forms of political ordering.