Maximin, Viability and Sustainability

The maximin criterion defines the highest utility level which can be sustained in an intergenerational equity perspective. The viability approach characterizes all the economic trajectories sustaining a given, not necessarily maximal, utility level. In this paper, we exhibit the strong links between maximin and viability: We show that the value function of the maximin problem can be obtained in the viability framework via a static optimization problem under constraints. This result allows us to extend the maximin approach beyond optimality and characterize the sustainability of other economic trajectories. In particular, we show how the maximin value and viability kernel can be combined as sustainability indicators along any economic trajectory. Attention is especially paid to positive net investment at maximin prices, which is shown to be necessary to maintain the productive capacities of the economy. The Dasgupta-Heal-Solow model illustrates the assertions.