Justifying Sustainability While Taming Longtermism: A Pluralistic Approach to Intergenerational Justice

How should the interests of different generations be balanced when considering both the issue of taming the extreme demands by strong longtermism on the present as well as ensuring a sustainable development that protects the well-being of generations in the far future? We adopt a pluralistic ethical approach which determines sets of intergenerational distributions that are robustly deemed morally unacceptable by considering only comparisons where there is unanimity among all elements in an entire class of commonly accepted distributional norms. In the setting of a simple technological environment we demonstrate that any morally unacceptable stream is dominated in terms of the moral criterion by some morally permissible stream. Furthermore, we show that increased productivity and an extended time horizon make it morally permissible for the present generation to incur greater sacrifices for future—in line with longtermism—while not obliging it to renounce an equal share of well-being.