Decision-making, expertise and partially verifiable information.

Summary Our contemporary societies are more and more marked by a search for productivity and rationalization. This requires the possession and proper use of information (whether economic, scientific, technological, social or political). Thus, the activities of expertise and communication are growing. The producers and transmitters of information (experts) can, by strategically manipulating the information transmitted, influence decision making. This thesis studies from a theoretical, normative and positive point of view, the impact of the possibilities of information certification on those of decision manipulation. In a first part, we deal with a consultative decision making (experts are consulted by decision makers). In the second part, we deal with deliberative decision making (the decision making is directly entrusted to the experts who have to give their opinion after deliberation).