Prioritarianism and Climate Change Maddalena Ferranna and Marc Fleurbaey1 December 2020 Abstract The paper compares utilitarianism and prioritarianism as alternative social welfare frameworks for evaluating climate policies. We review the main debates in the climate policy literature concerning the parameters of the utilitarian social welfare function, and discuss the analytical requirements and climate policy implications of prioritarianism both in deterministic and stochastic settings. We show that, given the specific characteristics of the climate issue and the assumptions routinely made in the climate literature, prioritarianism tends to support more lenient climate policies than undiscounted utilitarianism. This is based on the assumption of economic and social progress that makes the current generation worse-off than future generations. The presence of catastrophic climate outcomes that endanger the living conditions of future generations (or of the poorest individuals living in the future) relaxes this result. Keywords: climate change, prioritiarianism, social cost of carbon, utilitarianism, inequality, climate policy, damage risk JEL Classification numbers: D63, D81, Q54 1 The paper was prepared for inclusion as a chapter in a forthcoming Cambridge University Press volume entitled “Prioritarianism in Practice” edited by Matthew Adler and Ole Norheim. We thank the editors and participants at the Prioritarianism in Practice meetings on May 3-4, 2019 and May 21–22, 2020 for useful comments. Maddalena Ferranna (
[email protected]) is affiliated with the Harvard T.H. Chan School of Public Health and Marc Fleurbaey (
[email protected]) is affiliated with the Paris School of Economics. 1 1. Introduction Judgements about what is fair and morally defensible play a central role in designing climate policies.