This paper describes an approach to the operationalisation of extended peer communities that deploys uncertainty, ignorance and indeterminacy, and examines the crucial role of trust. Trust underwrites both the dialogue central to extended peer communities and the functional utility of the knowledge so created, because when "facts are uncertain, values in dispute, stakes high... and the framing of the problem involves politics and Values as much as science" (Ravetz J. Knowledge in an uncertain world. New Scientist 1990;127:2) the taken-for-granted trust in 'normal' science is no longer assured, necessitating the cultivation of trust by other means. It is argued that extended peer communities provide a focus for the ascendant politics of the post-normal realm, in resonance with recently articulated insights into broader social theory. "... we continue to believe in the sciences, but instead of taking in their objectivity, their truth, their coldness, their extraterritoriality... we retain what has always been most interesting about them: their daring, their experimentation, their uncertainty, their warmth, their incongruous blend of hybrids, their crazy ability to reconstitute the social bond. We take away from them only the mystery of their birth and the danger their clandestineness posed to democracy" (Latour B. We have never been modern. Hemel Hempstead (UK): Harvester Wheatsheaf, 1993:142). (C) 1999 Published by Elsevier Science Ltd. All rights reserved.