Expert knowledge and decision-making in controversy contexts

There was a time when the mobilization of experts was a taken-for-prated. unproblematic aspect of decision-making processes. That confidence has vanished. Ascertaining the significance of expertise now requires a reconsideration of the dynamics of controversies. The current view still assimilates conlroversy to the medieval exercise of the disputatio in which two parties argue one against the other. A non-reductionist view is needed to take fully into account the diversity of worlds of relevance involved in the dynamics of any public controversy. Only then is it possible to understand how decision making is predicated upon associations of worlds of relevance, and how expertise is actually a collective learning process which sets the boundary conditions for the efficacy of individual experts.