Consumption Externalities, Habit Formation and Equilibrium Efficiency*
研究在同时存在习惯形成和消费溢出时竞争均衡的福利性质，发现消费外部性需与习惯相互作用才会导致动态无效率，并设计了恢复效率的最优税收政策。
Abstract We analyze the welfare properties of the competitive equilibrium in a capital accumulation model where individual preferences are subject to both habit formation and consumption spillovers. Using an additive specification for preferences, according to which the argument in the utility function is a linear combination of present and past values of own consumption and consumption spillovers, we analyze the circumstances under which these spillovers are a source of inefficiency. It is shown that consumption externalities have to interact with habits in order to generate an inefficient dynamic equilibrium. Finally, we characterize optimal tax policies aimed at restoring efficient decentralized paths.