[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...

The quality of the coordination of expectations, a key issue for monetary policy, obtains from different, but interrelated, channels: both the credibility of the central bank intervention and the ability of decentralized agents to coordinate on a dynamical equilibrium matter. For both purposes,...

A model of organization is proposed in which factors for increasing returns to size and factors for decreasing returns to size are in co nflict. The former effect reflects standard efficiency gains associat ed with economies of scale. The latter arises from inefficiencies (which are modeled in a...

The authors consider a principal-agent contracting problem under incomplete information where some of the agent's actions are imperfectly observable. Contracts take the form of reward schedules based on the noisy observation of the agent's action. They first review situations where the principal...