Abstract

Nanotechnology as an emerging field is strongly related to visionary prospects which are disposed to reappear as dystopian concerns. As long as nanotechnology does not provide reliable criteria for assessing these worries as rational or as irrational they remain a challenge for ethical reflection. Given this underdetermination, many nanovisions and their corresponding concerns should therefore be considered as “arational.” For that reason, a “constructivist” stance is endorsed which does not seek to take part in discussions as to how ethicists should cope with controversial worries, but tries to observe how concerns are managed by different social actors. This perspective allows us to remodel some concerns such as “grey goo” not solely as a societal reaction, but also as challenging and irritating factors. As such they potentially initiate two different processes simultaneously: a differentiation in terms of demarcating science from non-science on the one hand, and a rationalization of concerns on the other. Analyzing these processes empirically allows to reconstruct how “arational” concerns are socially made rational or, on the contrary, irrational