This paper assumes that workers can move from a market with high unemployment to one with low unemployment at a cost. In principle. equilibrium mobility can be greater or less than the social optimum. For most plausible parameter values. however. mobility is too low. Intuitively. mobility has a...

We illustrate the welfare benefit of tax subsidies to corporate debt financing. Two firms engage in a socially wasteful competition for survival in a declining industry. Firms differ on two dimensions: exogenous productivity and endogenously chosen amount of debt financing, resulting in a two...

We propose a novel theory of self-fulfilling unemployment fluctuations. According to this theory, a firm hiring an additional worker creates positive external effects on other firms, as a worker has more income to spend and less time to search for low prices when he is employed than when he is...

Climate change is a global "free rider" problem because significant abatement of greenhouse gases is an expensive public good requiring international cooperation to apportion compliance among states. But it is also a global "free driver" problem because geoengineering the stratosphere with...

This paper develops a simple model of a polluting industry and an innovating firm. The polluting industry is faced with regulation and costly abatement. Regulation may be taxes or marketable permits. The innovating firm invests in R&D and develops technologies which reduce the cost of pollution...