Pre-print, Working paper: This is the text of the “Jean Jacques Laffont lecture”, closing the 2010 Congress of the AFSE, “Association Française de Science Economique”. The first part comes back on the standard economic viewpoint on expectational coordination, a viewpoint that the recent events have challenged. The second part reviews the existing directions for a critical assessment of the rational expectations hypothesis. The third part shows how such a critical assessment, along the lines of the so-called “eductive” learning approach, radically modifies our view of three key problems : the economic benefit of speculation, the informational efficiency of markets and, last but not least, the ability of long horizon agents to anticipate the future.