Recent years have seen the development of new theories of market failure based on asymmetric information and network effects. According to the new paradigm, we can expect substantial failure in the markets for labor, credit, insurance, software, new technologies and even used cars, to give but a...

This paper reviews and puts into perspective recent work reassessing the first and second Fundamental Theorems of Welfare Economics. It assesses the implications of the Greenwald-Stiglitz theorem establishing the (constrained) Pareto inefficiency of market economies with imperfect information...