The present value model of the current account has been very popular, as it provides an optimal benchmark to which actual current account series have often been compared. We show why persistence in observed current account data makes the estimated optimal series very sensitive to small-sample...

The author analyzes the optimal investment in environmental protection in a model of an infinite series of non-overlapping hyperbolically discounting agents. He shows that without a commitment mechanism society is eventually stuck in a situation where all agents prefer further investment in the...

Equal treatment for the present and the future was required in two axioms for sustainable development introduced by the author. This article shows that the two axioms are equivalent to awareness of physical limits in the long run future. We prove that two optimization problems are equivalent :...