This book surveys how economists engage with knowledge and beliefs in various fields of economic analysis, such as general equilibrium theory, decision theory, game theory, experimental economics, evolutionary theory of the firm, financial markets and the history of economic thought.

[eng] This text is a slightly revised version of the opening lecture to the “ Journées de l’Association Française de Science Économique ” (Rennes , 2004). In keeping with the rules of the exercise, the article provides a broad assessment of the difficulties and usefulness of...