There is a general presumption that social preferences can be ignored if markets are competitive. Market experiments (Smith 1962) and recent theoretical results (Dufwenberg et al. 2008) suggest that competition forces people to behave as if they were purely self-interested. We qualify this view....

Recent theoretical work in the economics of climate change has suggested that climate policy is highly sensitive to "fat-tailed" risks of catastrophic outcomes (Weitzman, 2009b). Such risks are suggested to be an inevitable consequence of scientific uncertainty about the effects of increased...